Anatomy and Physiology

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D’Abaldo’s Christian Master Herbalist School
Anatomy and physiology

Chapter one : Anatomical Organization
What are Anatomy and Physiology?
I. Anatomy: Study of the structure of body parts and their relationship to one another
A. Types of Anatomy:
1. Gross
a. Regional
b. Systemic
c. Surface
2. Microscopic
a. Cellular
b. Histology
3. Developmental
a. Embryology

II. Physiology: Study of the function of the body’s machinery; need to know underlying
anatomy to explain physiology
A. Typed based on specific organ systems
B. Requires understanding of chemistry and physics (next two lectures)
C. Function reflects structure

III. Organization of the Human Body: chemical, cellular, tissue, organ, organ system, organismal

A. Tissue: similar cells with common function (Chapter 4)
1. Types of tissue: epithelia, muscle, connective, nervous
B. Organ: structure with two or more tissue types (usually all four)
C. Organ System: Organs that work closely with one another to achieve a common function
1. Examples: cardiovascular, digestive, nervous

D. Organismal: (highest level) sum of all structural levels working in unison to promote life
IV. Maintaining Life
A. Necessary life functions
1. Boundaries
2. Movement
3. Responsiveness
4. Digestion
5. Metabolism
6. Excretion
7. Reproduction
8. Growth
B. Requirements for life
1. Nutrients

2. Oxygen
3. Water
4. Normal body temperature
5. Atmospheric pressure

V. Regulation of Bodily Activity
A. Homeostasis: ability to maintain stable internal conditions
1. Most organ systems work in concert to keep condition within a narrow range
a. Primarily achieved by nervous and endocrine function

2. Control system design:
a. Variable: factor or event being controlled
b. Mechanisms (three or more)

i. Receptor
ii. Control center
iii. Effector
3. Feedback control
a. Positive—increase stimulus
b. Negative—decrease stimulus
4. Negative Feedback: (most common) net effect is system output shuts off or reduces orig inal
stimulus’s intensity
a. Variable changes in the opposite direction of the initial change
b. Example: glucose regulation
5. Positive Feedback: change proceeds in the same direction as the original stimulus
a. Not common
b. Do not require constant adjustment
c. Events are self-perpetuating
d. Cascades
e. Example: blood clotting

VI. Anatomical Terminology
A. General Terms:
Superior
Inferior
Anterior
Posterior
Medial
Lateral
Intermediate

Proximal
Distal
Superficial
Deep
B. Regional Terms
Axial: main axis
Appendicular: appendages

C. Body Planes

1. Sagital
2. Frontal
3. Transverse

D. Body Cavities
1. Dorsal part of axial portion of body
a. Cranial
b. Vertebral
2. Ventral part of axial portion of body

a. Thoracic

i. Pleural cavities (lungs)
ii. Mediastinum
1. Medial: pericardial cavity (heart)
2. Superior: trachea, esophagus and remaining thoracic
b. Abdominopelvic: separated from thoracic by diaphragm; not truly divided (arbitrary)

i. Superior region—abdominal
ii. Inferior region--pelvic
E. Membranes: serosa

1. Parietal serosa
2. Visceral serosa
3. Types
a. Pericardium parietal and visceral serosa
b. Pleura parietal and visceral serosa
c. Peritoneum parietal and visceral serosa
Lecture 4: Cellular Biology I
I. Cell Theory
Concepts:
1. Cells are the functional and structural units of living organisms
2. The activity of an organism is dependent on both the individual and collective activity of the
cells that comprise that organism
3. Subcellular structures determine the biochemical activities of cells (i.e., principle of
complementarity)

4. Continuity of life has a cellular basis

II. Generalized Cell

A. Major parts
1. Nucleus
2. Cytoplasm
a. Contain organelles (see below)
3. Plasma membrane

III. Plasma Membrane

A. Fluid mosaic model
1. Membranes are a mosaic of different proteins are embedded in a phospholipid bilayer
2. Hydrophilic portions of both proteins and phospholipids are maximally exposed to water
3. Hydrophobic portions are in the nonaqueous environment inside the membrane

B. Types of proteins:
1. Integral: transmembrane proteins; span the hydrophobic interior
a. Channels
b. Carriers
2. Peripheral: not embedded; attached to surface
a. Enzymatic activity
b. Structure

C. Carbohydrates associated with the exterior surface of the membrane
1. Glycolipids
2. Glycocalyx: attached to proteins in contact with extracellular matrix

D. Function of membrane proteins:
1. Transport
2. Enzyme
3. Receptor sites
4. Intercellular junctions
5. Cell-cell recognition
6. Cytoskeletal and extracellular matrix attachment

E. Specialized Structures and Functions
1. Microvilli: increase surface area; absorption
2. Membrane junctions
a. Tight junctions—impermeable junctions
b. Desmosomes—anchoring junctions; plaques and linkers; intermediate filaments
c. Gap junctions—movement of chemicals between adjacent cells; connexons

F. Membrane transport
1. Membranes are selectively permeable
2. Movement across membranes
a. Passive and active processes
3. Passive movement: Diffusion

a. Net movement of a substance down a concentration gradient
i. Concentration gradient—graded concentration change over a distance in a
particular direction
b. Results from intrinsic kinetic energy
i. Affected by temperature and molecular size
c. Random molecular movement
d. Continues until a dynamic equilibrium is reached
4. Types of diffusion
a. Simple—nonpolar substances that are lipid soluble pass directly through lipid bilayer
i. Polar and charged particles can diffuse if they can fit through pores
b. Osmosis—diffusion of a solvent through a selectively permeable membrane
i. Hypertonic solution—solution with a greater solute concentration than inside a
cell
ii. Hypotonic solution—solution with a lower solute concentration than inside a
cell
iii. Isotinic solution
iv. Osmolarity—total concentration of all solutes in a solution
v. Osmotic pressure—amount of pressure required to prevent net movement of
water into a solution
c. Facilitated diffusion—lipid insoluble molecules too large to diffuse through membrane
pores can move passively with carrier molecules
i. Selective—not just size and lipid solubility (specific)
ii. Limited by number of carrier molecules present (saturated)
5. Passive movement: Filtration—water and solutes are forced through a membrane or capillary
by hydrostatic pressure
a. Pressure gradient pushes solute-containing fluid out
6. Active Processes: Active Transport
a. Cell uses energy to move substances across the membrane

b. Transport molecules harvest energy from ATP to pump molecules against
concentration gradients
c. Coupled systems—move more than one substance
i. Symport—same direction
ii. Antiport—opposite direction
d. Sodium-Potassium Pump
i. Na+ binding (cytoplasm) stimulates ATP formation
ii. Phosphorylation causes conformational change
iii. Shape change releases Na+ to outside
iv. K+ binding causes phosphate release
v. Pump returns to original conformation
vi. K+ is released to inside
7. Bulk Transport (Active)
a. Exocytosis—substance is released from vesicle (membranous sac)
i. Fuses with membrane and releases contents to outside
b. Endocytosis—large substances progressively enclosed by membrane and taken into
cell

i. Phagocytosis

ii. Pinocytosis
iii. Receptor-mediated endocytosis
a. Coated pit
b. Clathrin

IV. Cell-Environment Interactions
A. Cell-adhesion molecules (CAMS)
1. Anchor cell to extracellular matrix and to each other
2. Cell migration
3. Cell signaling
B. Membrane receptors
1. Contact signaling
2. Electrical signaling
a. Voltage-gated channels
3. Chemical signaling
a. Neurotransmitter and hormone receptors act as ligands
b. Binding of ligand causes conformational change
i. Creates force (muscle)
ii. Opens and closes ion channel
iii. Activates an enzyme
c. G protein-linked receptors
i. Ligand binds to receptor
ii. G protein affects a second membrane system (enzyme or ion channel)
iii. Second messenger is created
iv. Signaling cascade is initiated

V. Cytoplasmic Organelles
A. Cytoplasm—cellular material inside cell
1. Most cellular activities occur here
2. Comprised of:
a. Cytosol—fluid in which other components are suspended
b. Organelles (see below)
c. Inclusions—non-functioning chemicals substances that may be unique to a given cell
type
B. Mitochondria—transduce energy into useable cellular work

1. Double membrane—structure similar to plasma membrane
a. Outer membrane—permeable to small solutes
b. Inner membrane—contains embedded proteins involved in cellular work

i. Cristae—folds of the inner membrane
c. Inner membrane space
d. Mitochondrial matrix—contains enzymes for metabolic steps of cellular respiration
C. Ribosomes—site of protein synthesis
1. Complexes of RNA and protein
2. Free in cytosol or bound to endoplasmic reticulum
D. Endomembrane System—interactive system of membranes that interact either directly
through physical contact or indirectly through vesicles
1. Vesicle—membrane-enclosed sacs that are pinched off portions of membranes moving from
one membrane to another
2. Endomembrane system includes:
a. Nuclear envelope
b. Endoplasmic reticulum
c. Golgi apparatus
d. Lysosomes
e. Vacuoles
3. Endoplasmic reticulum—network of membranous tubules and sacs (cisternae) within the
cytoplasm

1. Continuous with the nuclear envelope
2. Two regions—smooth ER and rough ER
3. Smooth ER—lacks ribosomes
a. Synthesis of lipids, phospholipids and steroids
b. Carbohydrate metabolism
c. Detoxifies drugs
d. Calcium storage
4. Rough ER—protein synthesis (has ribosomes)
a. Ribosomes attached to ER synthesize secretory proteins
b. Growing polypeptide is threaded through ER membrane (receptor site) into cisternal
space
c. Protein folds into native conformation
d. If a glycoprotein, oligosaccharides are enzymatically added to the secretory protein
e. Protein departs in a transport vesicle pinched off from the ER

5. Golgi apparatus—modifies, concentrates and packages rough ER products

a. Organelle of stacked, flattened membranous sacs (cisternae)
b. Has polarity
i. Cis face—receives transport vesicles from rough ER
ii. Trans face—pinches off vesicles
c. The rough ER products are modified as they move through Golgi apparatus

6. Lysomes—digestive compartments; membranous sac containing hydrolytic enzymes
a. Digest all major classes of macromolecules
b. Acidic
i. Pump H+ in from cytosol
c. Sequesters destructive enzymes from the cytosol
d. Functions:
i. Intracellular digestion—phagocytosis
ii. Recycle cellular organic material
iii. Programmed cell death
e. Role in disease—storage diseases
i. Lack specific lysosomal enzymes which causes substrate accumulation
ii. Pompe’s—glycogen in liver
iii. Tay-Sachs—lipid accumulation in brain

VI. Cytoskeleton—network of fibers throughout the cytoplasm that form a framework for
support and movement and regulation
A. Functions:
1. Mechanical support to maintain shape
2. Allows cell to change shape when environment changes
3. Associated with motility (has motor molecules—see later lectures)
4. Regulatory role in transmitting signals from cell’s surface to its interior
B. Constructed from three types of fibers:

1. Microtubules (thickest)
a. Radiate from cell’s center
b. Determine cell shape
c. Provide tracks for organelle movement

d. Invovled in separation of chromosomes during cell division
2. Microfilaments (thinnest)
a. Made up of contractile protein (actin)
b. Attach to cytoplasmic side of plasma membrane
c. Participate in muscle contraction
d. Localized cell contraction
3. Intermediate filaments—most stable and permanent cytoskeletal element
a. Act as guy wires to resist pulling forces on the cell
b. Fix organelle position
Lecture 5: Cellular Biology II
I. Nucleus: control center for cellular function; contains genetic material
A. Number of nuclei
1. Most cells have a single nucleus
2. Large cells (those with a large amount of cytoplasm) have to be multinucleate
3. Red blood cells—only cell lacking a nucleus
B. Structures
1. Nuclear envelope
a. Double membrane—inner and outer
i. Outermembrane is continuous with ER
ii. Nuclear pores
iii. Selectively permeable
b. Perinuclear cisterna—fluid between membranes
2. Nucleoli
a. No membrane
b. Ribosomes subunits are assembled here

i. Large in growing cells
c. Associated with chromatin region associated with DNA coding for rRNA
i. Nuclear organizing regions (DNA regions)
3. Chromatin—DNA + globular histone
a. Nucleosome—fundamental unit of chromatin
i. Units of eight wrapped by DNA molecule
b. Chromosomes: prior to cell division, chromatin condenses to form chromosomes

II. Cell Life Cycle
The cell cycle includes all events from a cell’s formation until it divides. The cell cycle includes
two major periods: interphase and cell division (mitosis).
A. Interphase: from cell formation until cell division
1. Metabolic or growth phase: all non-replication activities
2. Preparation for division
3. Subphases:
a. G1: growth phase with little cell division related activites
i. Can last minutes to years (G0)
b. S: synthetic phase; DNA replicates
c. G2: brief period of growth where enzymes and other proteins necessary for division
are synthesized
i. Very brief
4. DNA replication (Do not need to know molecular events)
B. Cell Division
1. Mitosis and cytokinesis
2. Characteristics of mitosis
a. Daughter cells (2) are identical to mother cell

b. No gain or loss of genetic material
c. Series of continuous events
d. Lasts about two hours
3. Phases of mitosis
a. Prophase
i. Prior to the start of prophase, centrioles have replicated (two pairs)
ii. Chromatin condenses to form chromosomes
iii. Chromosomes already replicated and consist of two sister chromatids
iv. Sister chromatids are connected by centromere
v. Nuceoli disappear
vi. Centriole pairs are rearranged to focal loci for mitotic spindles (microtubules)
vii. Nuclear membrane disappears and spindles interact with chromosomes
viii. Spindles attach to kinetochores (proteins on centromere)
ix. Kinetochore microtubules pull chromatids to center of the cell
b. Metaphase
i. Chromosomes cluster at the middle of the cell
ii. Metaphase plate
c. Anaphase
i. Centromeres of the chromosomes split
ii. Each chromatid is now a chromosome
iii. Kinetochore fibers contract and pull chromosomes towards poles
iii. Poles of cells are pushed apart to elongate the cell
iv. V-shaped
v. Shortest stage; minutes
d. Telophase

i. Chromosome movement stops
ii. Chromosomes uncoil to form chromatin
iii. Nuclear membrane reforms
iv. Nucleoli reform
v. Spindles disassemble
4. Cytokinesis—peripheral microfilaments contract at the cleavage furrow to squeeze the cells
apart

C. Meiosis (Chapter 28): gamete production; two consecutive divisions produce four daughter
cells each with half as many chromosomes as mother cell
1. Nuclear divisions: Meiosis I and meiosis II
2. Meiosis I (preceded by interphase where DNA is replicated): Reduction Division
a. Prophase I
i. Chromosome form, nuclear membrane and nucleolus disappear
ii. Synapsis: homologous chromosomes form tetrads; crossover points form
(chiasmata)
b. Metaphase I
i. Tetrads align on equatorial plate
c. Anaphase I
i. Centromeres do not break (sister chromotids remain paired)
ii. Homologous chromosomes separate, breaking at crossover points (exchange
parts of chromosomes)
iii. Paternal and maternal chromosomes are separated
d. Telophase I
i. Same events as telophase of mitosis
ii. Cytokinesis follows
iii. Daughter cells are haploid (Diploid amount of DNA but haploid chromosomal
number)

3. Meiosis II (Like mitosis without DNA replication during interphase)
a. Four daughter cells are produced each genetically unique from original mother cells

III. Cancer
Terms:
A. Neoplasia—increase in new cells
1. Dystrophy—disorder arising from abnormal change in cell size
a. Hypertrophy—increase in size of cells
2. Dyplasia—disorder arising from abnormal change in cell number
a. Hyperplasia—increase in number of cells
b. Aplasia—decrease in cell number
i. Normal during development
ii. Occurs later in life (e.g., dementias, osteoporosis)
B. Tumor—unchecked growth of genetically abnormal cells
1. Classification based on characteristics
a. Benign
i. Looks like normal tissue
ii. Grows slowly
iii. Does not invade
b. Malignant: Cancer
i. Poorly differentiated
ii. Grow fast
iii. Invasive
iv. Metastasize
2. Classification based on origin

a. Carcinomas—epithelial origin
i. Glandular
ii. Squamous
iii. Melanocyte
b. Sarcomas—connective tissue origin
i. Cartilage
ii. Bone
iii. Fibrous connective
iv. Meninges
3. Classification based on prognosis or therapy
a. Tumor mass
b. Lymph involvement
c. Metastasis

C. Epidemiology—cause of disease; factors that lead to cancer
For a few rare situations, there are known genetic defects (e.g., retinoblastoma) or viral agents
(e.g., Burkitt’s lymphoma). But for most other cancers, the specific cause is not known.
A. Risk factors
1. Host factors
a. Age
b. Sex
c. Psychological factors
d. Genetic factors
2. Environmental and lifestyle factors
a. Geographic location
b. Nutrition

c. Occupation
i. Asbestos
ii. Pesticides
iii. Radiation
d. Cigarette smoking

D. Etiology
1. Cancer has no single cause. Its etiology is complex, requiring both:
a. DNA damage
b. Inadequate physiological defense or repair
2. Initiation of cancer—Neoplastic Transformation
a. Arise from a single cell
b. Cell suffers multiple transforming genetic mutations
i. Mutations are either inherited or acquired
3. Acquired mutations
a. Random events during DNA replication
b. Induced by mutagens (carcinogens)
4. Initial DNA damage promotes accumulation of further damage
a. Damage typically involves genes that normally:
i. Induce cell proliferation or growth (proto-oncogenes)
ii. Inhibit growth of damaged cells (tumor suppressor genes)

E. Treatment
1. Surgery—resection of the tumor
2. Radiation therapy—x-rays or gamma rays delivered to the tumor; induce apoptosis in
radiosensitive cells (including normal cells)

3. Chemotherapy (antineoplastic agents)—cytotoxic drugs that induce DNA damage; normal
cells are often better at repair and less vulnerable to apoptosis
4. Bone marrow transplantation—certain cancers require high doses of radiation or
chemotherapy; such treatment is toxic to bone marrow
5. Biological response modifiers—agents that boost immune system response or antagonize
tumor growth through other biological effects (e.g., interferon, cytokines, etc.)
6. Gene therapy—modify gene function; include synthetic nucleotide strands to repair DNA,
antisense strands to prevent gene expression, insertion of gene sequences to produce normal
gene products

End Cell Biology

Tissue I
Tissue—a group of closely associated cells performing a restricted range of functions.

Overview of Tissues

Tissue Type
Muscle
Epithelial
Contraction to Cover Exposed
Generate Force
Surfaces

Primary
Function

Nervous
Information
Processing

Cell Types

Neurons

Smooth

Squamous

Fibroblasts

Glia

Cardiac

Cuboidal

WBC’s

Skeletal

Columnar

Mast Cells

Transitional

Plasma Cells

Glandular

Macrophages

Fibers

(Minimal)

(Minimal)

Basement
Membrane

Connective
Structure and
Support

Adipocytes
Collagen
Reticular

Elastic

Fluids

Nutrient-Rich,
Aqueous

(Minimal)

(Limited)

I. Classes of Tissue
A. Nervous Tissue
1. Neurons
a. Chemical and electrical transmission of information
2. Glia
a. Support and repair

B. Muscle
1. Function: Contracts to generate force
2. Types
a. Skeletal
i. Striated
ii. Multinucleated
iii. Voluntary control
b. Smooth
i. Non-striated
ii. Uninucleated
iii. No voluntary control
c. Cardiac

Depends on
Type of
Connective
Tissue

i. Striated
ii. Intercalated disks
iii. No voluntary control

C. Epithelial
1. Functions:
a. Protection
b. Absorption
c. Filtration
d. Secretion
2. Characteristics
a. Cellularity: close-packed cells with limited extracellular material
b. Cellular connections
i. Tight junctions
ii. Desmosomes
c. Cellular organization
i. Apical surface in contact with fluid or air
ii. Basal cell layer in contact with basement membrane (lamina)
d. Connective tissue support
i. All epithelial sheets are supported by connective tissue
ii. Deep to the basement lamina is a layer of connective tissue—reticular lamina
iii. Basement lamina + reticular lamina = basement membrane
e. Innervated—receives nervous innervation
f. Avascular—contains no blood vessels
g. Highly regenerative

i. Cells are replaced rapidly by cell division
ii. Cell loss due to friction and contact with hostile environments

3. Classification

4. Nomenclature
a. Two names
i. First indicates number of cell layers
ii. Second indicates cell shape
b. All cells in a given layer will have the same shape
5. Epithelial layers
a. Simple
i. Single cell layer
ii. Areas of absorption and filtration
b. Stratified
i. Two or more cell layers
ii. Areas of high abrasion
6. Cell shape: all cells have six irregular sides that differ in height
a. Squamous
i. Flattened
ii. Scale-like
b. Cuboidal
i. Boxlike
ii. As tall as wide
c. Columnar
i. Tall
7. Shape of nucleus
a. Conforms to cell shape

i. Squamous—disc shaped
ii. Cuboidal—spherical
iii. Columnar—elongated from top to bottom
8. Types of Simple Epithelia
a. Simple squamous
b. Simple cuboidal
c. Simple columnar
d. Pseudostratified columnar
9. Types of Stratified Epithelia
a. Stratified squamous
i. Cell shape varies according to layer
ii. Name is based on shape of apical surface
b. Stratified cuboidal
c. Simple columnar
d. Transitional epithelia

Nonglandular Epithelia
I. Simple
A. Simple squamous
1. Function
a. Diffusion and filtration
2. Location
a. Endothelium
i. Lining of lymphatic system
ii. Lining of all organs in cardiovascular system

b. Mesothelium
i. Serous membrane linings of ventral body cavity
B. Simple cuboidal
1. Function
a. Secretion and absorption
C. Simple columnar
1. Function
a. Absorption and secretion
2. Location
a. Digestive tract
3. Modifications
a. Dense microvilli on apical surface
b. Goblet cells that secrete protective lubricant
D. Pseudostratified columnar
1. Single layer of cells that vary in height
2. Only tallest reach apical surface
3. Nuclei are located at different heights
4. Function
a. Absorption and secretion
5. Modifications
a. Ciliated with mucous cells
i. Mucous traps particulate matter
ii. Cilia propel trapped matter out

II. Stratified epithelia

A. Characteristics
1. Two or more cell layers
2. Regenerate from below via mitotic division
a. Basal cell divide
b. Move apically to replace older surface cells
3. Durable
4. Protection
B. Stratified squamous
1. Surface cells are squamous
2. Deep layers consist most often of cuboidal
3. Location
a. Areas of abrasion
b. Forms external surface of the body
i. Extends into all body openings
ii. Outer layer (epidermis) is keratinized
4. Surface cells are flattened and atrophied
C. Stratified cuboidal and columnar are rare
D. Transitional
1. Location
a. Lining of urinary organs
i. Need to stretch (undergo a transition)
2. Cell organization
a. Basal surface—cuboidal or columnar
b. Apical surface
i. Unstretched—rounded and dome-like

ii. Stretched—flattened; squamous-like
c. Cell layers
i. Unstretched—six layers
ii. Stretched—three layers

Glandular Epithelia
A. Terms:
1. Gland: consist of one or more cells that make and secrete a particular product
2. Secretion: refers to both the aqueous product of glandular cells and the process of making
that product
a. Formation involves active processes
i. Made in ER, packaged in Golgi (secretory vesicles), secreted by exocytosis
B. Classification
1. Route of secretion
a. Exocrine
i. Secrete via ducts
Secrete onto body surface or cavities
b. Endocrine (Discussed later)
i. Ductless
ii. Secrete directly into extracellular space
2. Cell number
a. Unicellular
b. Multicellular
C. Multicellular exocrine glands
1. Common elements
a. Duct derived from epithelium

b. Secretory unit consisting of secretory cells
c. Supportive connective tissue
i. Supplies blood and nervous fibers
d. Fibrous capsule
i. May penetrate gland and divide it into lobes
2. Classification based on duct structures
a. Simple
i. Single unbranched duct
b. Compound
i. Branched duct
3. Classification based on secretory parts
a. Tubular
i. Secretory cells form a tube
b. Alveolar
i. Secretory cells form a flask-like sac
c. Tubuloalveolar
i. Contain both
4. Classification based on how product is secreted
a. Merocrine glands
i. Secrete via exocytosis without altering secretory cell
b. Holocrine glands
i. Accumulate products until cell bursts, releasing secretory products, then dies
c. Apocine glands
i. Accumulate products just beneath free surface
ii. Top of cell is removed and products are released

iii. Cell is repaired
D. Unicellular exocrine glands
1. Single cells scattered in epithelial sheet
2. Ductless
3. Goblet cells
a. Produce mucin
b. Protects and lubricates surfaces
Structural Organization
Tissue I
Tissue—a group of closely associated cells performing a restricted range of functions.

Overview of Tissues

Tissue Type
Muscle
Epithelial
Contraction to Cover Exposed
Generate Force
Surfaces

Primary
Function

Nervous
Information
Processing

Cell Types

Neurons

Smooth

Squamous

Fibroblasts

Glia

Cardiac

Cuboidal

WBC’s

Skeletal

Columnar

Mast Cells

Transitional

Plasma Cells

Glandular

Macrophages

Fibers

(Minimal)

(Minimal)

Basement
Membrane

Connective
Structure and
Support

Adipocytes
Collagen
Reticular
Elastic

Fluids

Nutrient-Rich,
Aqueous

(Minimal)

(Limited)

I. Classes of Tissue
A. Nervous Tissue

1. Neurons
a. Chemical and electrical transmission of information
2. Glia

Depends on
Type of
Connective
Tissue

a. Support and repair

B. Muscle
1. Function: Contracts to generate force
2. Types
a. Skeletal
i. Striated
ii. Multinucleated
iii. Voluntary control
b. Smooth
i. Non-striated
ii. Uninucleated

iii. No voluntary control
c. Cardiac
i. Striated
ii. Intercalated disks
iii. No voluntary control

C. Epithelial

1. Functions:
a. Protection
b. Absorption
c. Filtration

d. Secretion
2. Characteristics
a. Cellularity: close-packed cells with limited extracellular material
b. Cellular connections
i. Tight junctions
ii. Desmosomes
c. Cellular organization
i. Apical surface in contact with fluid or air
ii. Basal cell layer in contact with basement membrane (lamina)
d. Connective tissue support
i. All epithelial sheets are supported by connective tissue
ii. Deep to the basement lamina is a layer of connective tiss ue—reticular lamina
iii. Basement lamina + reticular lamina = basement membrane
e. Innervated—receives nervous innervation
f. Avascular—contains no blood vessels
g. Highly regenerative
i. Cells are replaced rapidly by cell division
ii. Cell loss due to friction and contact with hostile environments

3. Classification

4. Nomenclature
a. Two names
i. First indicates number of cell layers
ii. Second indicates cell shape
b. All cells in a given layer will have the same shape
5. Epithelial layers
a. Simple
i. Single cell layer
ii. Areas of absorption and filtration
b. Stratified
i. Two or more cell layers
ii. Areas of high abrasion
6. Cell shape: all cells have six irregular sides that differ in height

a. Squamous
i. Flattened
ii. Scale-like
b. Cuboidal
i. Boxlike
ii. As tall as wide
c. Columnar
i. Tall
7. Shape of nucleus
a. Conforms to cell shape
i. Squamous—disc shaped
ii. Cuboidal—spherical
iii. Columnar—elongated from top to bottom
8. Types of Simple Epithelia
a. Simple squamous

b. Simple cuboidal

c. Simple columnar

d. Pseudostratified columnar

9. Types of Stratified Epithelia
a. Stratified squamous

i. Cell shape varies according to layer
ii. Name is based on shape of apical surface
b. Stratified cuboidal

c. Stratified columnar

d. Transitional epithelia

Nonglandular Epithelia
I. Simple
A. Simple squamous
1. Function
a. Diffusion and filtration
2. Location
a. Endothelium
i. Lining of lymphatic system
ii. Lining of all organs in cardiovascular system
b. Mesothelium
i. Serous membrane linings of ventral body cavity

B. Simple cuboidal
1. Function
a. Secretion and absorption
C. Simple columnar
1. Function
a. Absorption and secretion
2. Location
a. Digestive tract
3. Modifications
a. Dense microvilli on apical surface
b. Goblet cells that secrete protective lubricant
D. Pseudostratified columnar
1. Single layer of cells that vary in height
2. Only tallest reach apical surface
3. Nuclei are located at different heights
4. Function
a. Absorption and secretion
5. Modifications
a. Ciliated with mucous cells
i. Mucous traps particulate matter
ii. Cilia propel trapped matter out

II. Stratified epithelia
A. Characteristics
1. Two or more cell layers

2. Regenerate from below via mitotic division
a. Basal cell divide
b. Move apically to replace older surface cells
3. Durable
4. Protection
B. Stratified squamous
1. Surface cells are squamous
2. Deep layers consist most often of cuboidal
3. Location
a. Areas of abrasion
b. Forms external surface of the body
i. Extends into all body openings
ii. Outer layer (epidermis) is keratinized
4. Surface cells are flattened and atrophied
C. Stratified cuboidal and columnar are rare
D. Transitional
1. Location
a. Lining of urinary organs
i. Need to stretch (undergo a transition)
2. Cell organization
a. Basal surface—cuboidal or columnar
b. Apical surface
i. Unstretched—rounded and dome-like
ii. Stretched—flattened; squamous-like
c. Cell layers

i. Unstretched—six layers
ii. Stretched—three layers

Glandular Epithelia
A. Terms:
1. Gland: consist of one or more cells that make and secrete a particular product
2. Secretion: refers to both the aqueous product of glandular cells and the process of making
that product
a. Formation involves active processes
i. Made in ER, packaged in Golgi (secretory vesicles), secreted by exocytosis
B. Classification

1. Route of secretion

a. Exocrine
i. Secrete via ducts
Secrete onto body surface or cavities
b. Endocrine (Discussed later)
i. Ductless
ii. Secrete directly into extracellular space
2. Cell number
a. Unicellular
b. Multicellular
C. Multicellular exocrine glands
1. Common elements
a. Duct derived from epithelium
b. Secretory unit consisting of secretory cells
c. Supportive connective tissue
i. Supplies blood and nervous fibers
d. Fibrous capsule
i. May penetrate gland and divide it into lobes
2. Classification based on duct structures
a. Simple
i. Single unbranched duct
b. Compound
i. Branched duct
3. Classification based on secretory parts
a. Tubular
i. Secretory cells form a tube

b. Alveolar
i. Secretory cells form a flask-like sac
c. Tubuloalveolar
i. Contain both
4. Classification based on how product is secreted

a. Merocrine glands
i. Secrete via exocytosis without altering secretory cell
b. Holocrine glands
i. Accumulate products until cell bursts, releasing secretory products, then dies
c. Apocine glands
i. Accumulate products just beneath free surface
ii. Top of cell is removed and products are released

iii. Cell is repaired
D. Unicellular exocrine glands
1. Single cells scattered in epithelial sheet
2. Ductless
3. Goblet cells
a. Produce mucin
b. Protects and lubricates surfaces
Tissue II
I. Connective Tissue
A. Functions
1. Binding and support
2. Protection
3. Insulation
4. Transportation
B. Common Characteristics
1. Origin—all connective arise from mesenchyme
a. Mesenchyme is an embryological tissue derived from mesoderm germ layer
2. Vascularity varies based on type
3. Extracellular matrix
a. Nonliving
i. Ground substance
ii. Fibers
b. Separates the living components
c. Allows tolerance of force, abuse and trauma
C. Structural Elements

1. Ground substance
a. Fills space between cells
b. Contains fibers
c. Composition
i. Interstitial fluid
ii. Cell adhesion proteins—glues component together
iii. Proteoglycans—trap water; determine how stiff the ground substance is
2. Fibers—provide support
a. Types
i. Collagen fibers—made from collagen; strong, high tensile strength
ii. Elastic fibers—made from elastin; stretches and recoils to bring tissue back to
normal shape
iii. Reticular fibers—collagenous; branched and form networks; surround small
blood vessels and support tissue of organs
3. Cells—blasts and cytes
1. Undifferentiated Cell Types—mitotically active; secrete ground substance and fibers
a. Fibroblasts—connective tissue proper
b. Condroblast—cartilage
c. Osteoblast—bone
d. Hematopoietic stem cells—blood
2. “Cytes”—mature; support existing matrix
3. Other cells associated with connective tissue
a. Fat cells
b. WBC’s—mast cells, macrophages, etc.
i. Mast cells participate in inflammation; histamine; perforin
ii. Macrophages—phagocytize foreign materials

II. Types of Connective Tissue—based on cell type, fiber type, and matrix composition
A. Embryonic connective tissue—Mesenchyme

1. Present in embryological life
2. Derived from mesoderm germ layer
3. Differentiates into other connective tissue type
B. Connective tissue proper
1. Subclasses:
a. Loose connective tissue
i. Areolar
ii. Adipose

iii. Reticular
b. Dense connective tissue
i. Dense regular
ii. Dense irregular
iii. Elastic
2. Areolar (loose) connective tissue

a. Ground substance
i. Semi-fluid; viscous
ii. Hyaluronic acid
b. Fibers—all three types
i. Arranged loosely

c. Cells
i. Fibroblasts
ii. Macrophages
iii. Mast cells
d. Widely distributed throughout body
c. Binds body parts together
3. Adipose tissue—fat; modified areolar tissue used to store nutrients

a. Small amount of matrix
b. Adipose cells are densely packed together
i. Cell volume mostly oil droplet
c. Abundant (Male 15%; Female 22%)
d. Accumulates in subcutaneous tissue but can be anywhere

4. Reticular connective tissue

a. Resembles areolar but only contains reticular fibers
b. Fibroblasts and reticular cells
c. Forms internal framework in lymph nodes, spleen and bone marrow to support
lymphocytes and other blood cells
5. Dense regular (fibrous) connective tissue—mostly fibers; force in one direction

a. Bundles of collagen running in the same direction
i. Parallels direction of pull
b. Bundles are slightly wavy
i. Permits stretching
c. Fibroblast, few other cells
d. Tendons
i. Aponeuroses—flat sheet that connect muscles to bone or other muscles
e. Ligaments—bone to bone; have higher amount of elastin
6. Dense Irregular connective tissue—fibers run in multiple planes; oppose force in multiple
direction

7. Cartilage—intermediate properties between connective tissue and bone; tough but flexible
a. Avascular; no nervous tissue
b. Ground substance
i. Chrondroitin sulfate
ii. Hyaluronic acid
iii. Chondronectin—adhesive protein
iv. Bound collagen fibers
v. Contains up to 80% water
c. Association with dense irregular connective tissue (perichondrium)
i. Surrounds cartilage surface
d. Chondroblasts
i. Found in groups (lacunae)

e. Types of growth
i. Interstitial growth—within cartilage; early in development
ii. Appositional growth—onto superficial surfaces of cartilage
f. Growth stops at adolescence when skeleton matures
8. Varieties of cartilage
a. Hyaline

i. Most abundant
ii. Support with pliability
iii. Ends of long bones—articular cartilage; absorbs force of compression
iv. Embryonic skeleton prior to bone formation
v. Epiphyseal plates—actively growing regions of long bones

b. Elastic—similar to hyaline with more elastin fibers

i. Very flexible
ii. Outer ear; epiglottis
c. Fibrocartilage—connection between hyaline and ligament or tendon

i. Intermediate between cartilage and dense regular connective tissue
ii. Alternating rows of chondrocytes with collagen fibers
iii. Strong support, resistant to heavy pressure
iv. Intervertebral discs
9. Bone—matrix similar to cartilage but more rigid

a. High collagen content with inorganic salts
b. Osteoblasts—produce organic matrix
i. Lacunae
c. Vascular
10. Blood—cells surrounded by nonliving plasma (therefore connective tissue)

a. Matrix—soluble proteins
b. Transportation

*Bone, muscle and blood will be considered in depth in subsequent lectures

III. Epithelial Membrane—continuous multicellular sheet composed of at least two tissue types
(epithelia bound to underlying connective tissue); “simple organ”

A. Cutaneous membrane—skin
1. Keratanized stratified squamous attached to a thick layer of dense irregular connective tissue
2. Exposed to air
*To be discussed in detail during integument lecture
B. Mucous membrane—line cavities open to exterior; moist membranes
1. Stratified squamous or simple columnar epithelia
2. Function in absorption and secretion
3. Most secrete mucous, but not all (urinary tract)
4. Epithelia sheet attached to layer of loose connective tissue (lamina propria)
C. Serous membranes—moist membranes found in closed ventral cavities
1. Parietal and visceral layers
2. Simple squamous resting on a layer of loose connective tissue

Lecture 7: Integumentary System
The integument is the outer most covering of the body. Although commonly referred to as skin,
it also includes blood vessels, nerves and sensory receptors, sweat and oil glands, other
derivatives such as hair and nails. It is a complex organ that serves primarily a protective
function.
I. Regions

A. Epidermis—outermost layer; mostly epithelial cells; non-vascular
B. Dermis—fibrous connective tissue; vascular
C. Hypodermis (superficial fascia)—not skin; protective; adipose and loose connective tissue

A. Epidermis—thick keratinized stratified squamous epithelium consisteing of four cell types
and five layer

1. Cell types
a. Keratinocytes—produce keratin; primary cell of epidermis
i. Arise in stratum basale
ii. Pushed to surface as continuously mitotic cells reproduce
iii. Keratin is produced as cells migrate
iv. Cells connected by desmosomes
v. At surface, cells are dead keratin filled plasma membrane
b. Melanocytes—produce pigment, melanin

i. In stratum basale
ii. Have processes that contact all keratinocytes
iii. Transfer melanin to keratinocytes

iv. Melanin accumulates near cell’s apical surfaces to shield nucleus from UV
c. Merkel cells—associated with sensory nerve endings; form Merkel disc
d. Langerhan’s cells (epidermal dendritic cells)
i. Made in bone marrow and migrate to epidermis
ii. Form a continuous network
iii. Function as macrophages
2. Layers of epidermis

a. Stratum basale (stratum germinativum)—deepest layer
i. Single layer of mitotically active cells
ii. Give rise to keratinocytes (youngest)

iii. Includes melanocytes and some Merkel cells
b. Stratum spinosum (Prickly layer)—weblike network of cells formed by intermediate
filaments attached to desmosomes
i. Comprised of keratinocytes
ii. Includes melanin granules and Langerhans cells
c. Stratum granulosum—thick; 3-5 cell layers; keratinocytes are modified
i. Flattened; nuclei and organelles lost
ii. Keratohylaline and lamellated granules accumulate
iii. Lamellated granules are glycoproteins, released into extracellular space, that
reduce water loss
iv. Cells more resistant to destruction
d. Stratum lucidum—a few rows of clear, flattened, dead keratinocytes; layer occurs
only in thick skin
i. Keratohyalin granules—gummy substance associated with keratin filaments
ii. Cells aggregate in parallel arrays
e. Stratum corneum (Horny layer)—outer most layer; most of epidermis thickness
i. 20-30 cell layers thick
ii. Keratin, thickened plasma membranes and glycoproteins protect against
abrasion and loss of water
iii. Cornified or horny cells—remnants of cells from this layer

B. Dermis—strong, flexible tissue layer
1. Cells
a. Fibroblasts
b. Macrophages
c. Mast cells
d. WBC’s

2. Nervous fibers with sensory receptors
3. Blood vessels
4. Hair follicles
5. Swaet glands
6. Layers
a. Papilary layer—thin; superficial
i. Connective tissue with blood vessels
ii. Dermal papillae—superficial layer; project into epidermal layer; include
capillary beds, Meissner’s corpuscles
b. Reticular layer—most of dermis; dense irregular connective tissue
i. Collagen fibers—strength and resiliency; hydration
ii. Elastin fibers—stretch recoil

C. Skin color
1. Pigments
a. Melanin—ranges in color from yellow to redish-brown to black
i. Tyrosine derivative
ii. Tyrosinase
iii. Racial differences—amount and persistence of melanin in keratinocytes
iv. Melanocytes are stimulated by sunlight; protects DNA from UV
b. Carotene—yellow to orange
i. Accumulates in stratum corneum and fatty tissue of hypodermis
ii. Obvious in palms and soles
c. Hemoglobin—in RBC’s
i. Redish hue through transparent skin of caucasians lacking melanin
ii. Cyanosis—deoxygenated blood gives skin a blue appearance

2. Emotional and disease states
a. Redness (erythema)—embarrassment, fever, hypertension, inflammation, allergy
b. Pallor—paleness; emotional stress, anemia, low blood pressure
c. Jaundice—liver disorder (bile pigments in blood and deposited in body tissue)
d. Bruises—blood escapes circulatory system and forms a hematoma

D. Skin appendages

1. Sweat glands (sudoriferous)
a. Eccrine
i. Coiled, tubular
ii. Palms, soles of feet

iii. Duct opens to pore on surface
iv. Hypotonic secretion
v. Regulated by sympathetic NS
a. Involuntary
b. Apocrine
i. Large; ducts empty into hair follicle
ii. Axillary and anogenital areas
iii. Interaction with skin bacteria results in odor
c. Ceruminous—modified apocrine
I. Ear canal; cerumen (wax)
d. Mammary—produce milk
2. Sebaceous glands
a. Secrete sebum
i. Holocrine—accumulate lipids until they burst
ii. Slow water loss when humidity is low
iii. Softens hair
iv. Bactericidal
v. Stimulated by androgens
3. Hair and hair follicles

a. Warmth (not humans)
b. Sensory functions
c. Protection
d. Filtration
4. Nails—modification of epidermis

a. Free edge, body, proximal root

II. Function of the Integumentary System
A. Protection
1. Chemical barriers
a. Acid mantle—low pH selects against bacteria
b. Bactericidal substances in sebum
2. Physical and mechanical barriers
a. Skin is continuous and keratinized
b. Blocks movement of water soluble substances
c. Permits lipid soluble, organic solvents
3. Biological barriers
1. Immune responses initiated in skin

a. Antigen presentation to lymphocytes
i. Langerhan’s cells
b. Macrophage activity
B. Body temperature regulation

1. Endothermic evaporation cools body
a. Sweat glands secrete sweat continuously
b. Body temperature increase
i. Blood vessels dilate
ii. Sweat glands stimulated
C. Cutaneous sensation
1. Sensory receptors (externoceptors)

a. Meissner’s corpuscles--vibration
b. Pacinian corpuscles—deep pressure
c. Root hair plexuses
d. Nociceptors
D. Metabolic functions
1. Conversion of cholesterol into vitamin D precursor
E. Blood reservoir
1. Shunted by nervous function between skin reservoir (5% of volume) to general circulation
F. Excretion
1. Limited amount of nitrogenous wastes
2. Water and salts in sweat

Bones and the Skeletal System
Skeletal Tissue
The skeleton includes various types of connective tissues, primarily cartilage and bone. During
embryological life, the skeleton is primarily cartilage but this is replaced by bone with minor
amounts of cartilage persisting in adult life.

I. Structure and Location of Cartilage
A. Basic structure
1. Primarily water
2. Non-vascular
3. No nervous tissue
4. Perichondrium—dense connective tissue surrounding cartilage
5. Cellular components
a. Chondrocytes

i. Secrete extracellular matrix
B. Types of cartilage
1. Hyaline—most abundant
a. Articular cartilage
b. Costal cartilage
c. Laryngeal cartilage
d. Tracheal and bronchial cartilage
e. Nasal cartilage
2. Elastic—more elastic fibers
a. Ears and epiglottis
3. Fibrocartialge—compressible with tensile strength
a. Alternating parallel rows of chondrocytes and collagen
b. Sites of heavy pressure and stretch
i. Vertebral discs
ii. Knee
C. Growth
1. Appositional
a. Cartilage forming cells embedded in perichondrium layer
2. Interstitial
a. Chondrocytes within lacunae in center of cartilage

*Although cartilage can be calcified, calcified cartilage is not bone. Bone is a separate type of
connective tissue.

II. Bone
A. Function

1. Support
2. Protection
3. Movement
4. Mineral storage
5. Hematopoiesis

III. Classification of Bone
A. Type
1. Compact—external
2. Spongy—internal
B. Shape

1. Long bone
a. Longer than wide
b. Shaft with two ends
c. Mostly compact
d. Bones of limbs
2. Short bone
a. Cube-like
b. Mostly spongy
c. Sesamoid—bones embedded in tendon
i. Patella
3. Flat bone
a. Spongy bone embedded within parallel layers of thin compact bone
4. Irregular bone
a. Vertebrae and hip bones
b. Complicated shapes
c. Mostly spongy with a thin covering of compact bone

IV. Bone Structure
A. Structural levels
1. Gross anatomy
2. Microscopic anatomy
3. Chemical composition
B. Gross anatomy of long bones

1. Diaphysis: shaft; long axis
a. Constructed of a collar of thick compact bone
b. Central medullary cavity
i. Contains fat—yellow marrow
2. Epiphysis: bone ends
a. Exterior is compact bone
b. Interior is spongy bone
c. Articular cartilage covers joint surface
i. Absorbs stress
d. Epiphyseal line
i. Remnant of epiphyseal plate
ii. Region of hyaline cartilage that grows during development

3. Membranes

a. Periosteum
i. Double layer
ii. Fibrous outer layer; dense irregular CT
iii. Osteogenic—bone forming cells (osteoblasts); destroying cells (osteoclasts)
iv. Vascular, includes NT and lymph
v. Sharpey’s fibers: connect periosteum to bone; system of collagen fibers
penetrating bone; densest at muscle and tendon attachment points
b. Endosteum: covers trabeculae of spongy bone in marrow cavites
i. Contain osteoblasts and osteoclasts

C. Gross anatomy of short bones

a. Layer of spongy bone sandwiched between parallel layers of compact bone
b. Periosteum covers compact bone
c. Endosteum covers spongy bone
i. Spongy bone layer is referred to as diploe
d. Marrow not confined to a cavity
D. Hematopoietic tissue: Red marrow
a. Red marrow cavities
i. Spongy bone of long bones
ii. Diploe of short bones
b. In adults, fat containing medullary cavity extends into epiphysis
i. Little red marrow
c. RBC’s produced primarily in diploe

V. Microscopic Structure of Compact Bone
A. Structural unit: Haversian System; Osteon

1. Elongated cylinders parallel to bone long axis
a. Concentric rings: lamella
i. Unidirectional collagen fibers along long axis
ii. Adjacent lamella have collagen in opposite directions
2. Central (Haversian) canal: core of osteon
a. Blood vessels and NT
3. Perpendicular canals (perforating or Volkmanns)
a. Connect periosteum to central and medullary cavities
i. Blood supply and NT innervation
4. Lacunae: cavities containing osteocytes
5. Canaliculi: connect lacunae to each other and central canal

VI. Microscopic Structure Spongy Bone

A. Trabeculae: needle-like (flat) pieces
B. Trabeculae appear less organized than structures of compact bone
a. No osteon
b. Organization is based on lines of stress
c. Lamella and osteocytes are irregularly organized;

VII. Chemical Composition of Bone
A. Organic
1. Cells
a. Osteocytes

b. Osteoblasts
c. Osteoclasts
2. Osteoid: organic part of matrix; made by osteoblasts
a. Proteoglycans
b. Glycoproteins
c. Collagen fibers
B. Inorganic
1. Hydroxyapatites (mineral salts)
a. Calcium crystals in and around extracellular matrix
i. Make bones hard

VIII. Bone Marking
A. Sites of muscle and ligament attachment
1. Tuberosity
2. Crest
3. Trochanter
4. Line
5. Tubercle
6. Epicondyle
7. Spine
B. Projections that contribute to joint formation
1. Head
2. Facet
3. Condyte
4. Ramus

C. Depressions and opening permitting blood vessels and nerves to enter bone
1. Meatus
2. Sinus
3. Fossa
4. Groove
5. Fissure
6. Foramen

IX. Formation of Bone
A. Intramembranous ossification

1. Skull, clavicles, flat bones
2. Process:
a. Ossification center forms in fibrous connective tissue membrane
i. Mesenchymal cells differentiate into osteoblasts
b. Bone matrix is secreted into membrane
i. Osteoblast secrete osteoid
c. Woven bone and periosteum is formed
i. Network of trabeculae encloses local blood vessels
ii. Exterior mesenchyme differentiates into periosteum
d. Trabeculae thicken and form bone collar
i. Replaced by lamellar bone
ii. Spongy bone persists to form red marrow
B. Endochondral ossification

1. Cartilage bone are used as a pattern for bone construction
a. Primary ossification center at the center of the hyaline cartilage
2. Hyaline cartilage is broken down during ossification
3. Process prior to ossification

a. Perichondrium becomes infiltrated by blood vessels
i. Becomes periosteum
ii. Underlying mesenchymal cells differentiate into osteoblasts
4. Ossification

a. Bone collar forms around hyaline model
i. Osteoblasts in periosteum secrete osteoid against hyaline cartilage
b. Cartilage in center of the diaphysis calcifies
i. Chondrocytes hypertrophy
ii. Signal matrix to calcify
iii. Shaft is impermeable and chondrocytes die
c. Periosteal bud invades internal cavities
i. Bud brings blood vessels, NT, lymph tissue, osteoblasts and osteoclasts
ii. Osteoblasts secrete osteoid around remaining hylaline cartilage
d. Medullary cavity forms
i. Proximal and distal growth of ossification center
ii. Osteoclasts break down spongy bone and open medullary cavity

iii. Hyaline cartilage model continues to elongate and is chased by forming
ossifying shaft
e. Epiphyses ossify
i. At birth, diaphysis surround spongy done, medullary cavity is widening, and
epiphyses are cartilaginous
ii. Secondary ossification centers form in epiphyses prior to birth and follow
same course as that described above for primary ossification center
C. Postnatal Bone Growth
1. Length of long bones

a. Parallel events of endochondral ossification
i. Zone 1: Epiphyseal side; cartilage is added to top; bone lengthens
ii. Zone 2: Chondrocytes close to shaft; cartilage matrix ossifies

iii. Zone 4: Epiphyseal/diaphysis junction; cartilage spicules covered with bone
matrix to form spongy bone
iv. Spongy bone is digested by osteoclasts allowing medullary cavity to grow
2. Bone remodeling: maintain proper proportion by selective resorption and appositional
growth
3. Bone thickness: appositional growth

X. Bone Homeostasis
A. Remodeling

1. Balance of bone formation and resorption at perosteal and endosteal surfaces
a. Processes are balanced to maintain constant bone mass
b. Remodeling units

i. Packets of osteoblasts and osteoclasts
2. Differential
a. Bones and parts of bones remodel at different rates
3. Control of remodeling

a. Hormonal mechanism: not related to strength; associated with mineral balance
i. Parathyroid hormone (parathyroid gland)
ii. Calcitonin (thyroid gland)
iii. PTH released in response to low ionic calcium in blood
iv. Osteoclasts are activated to digest bone matrix and release calcium into blood
v. Calcitonin is released in response to high calcium in blood
vi. Calcium salts are deposited into bone

b. Mechanical stress: bone respond; mechanism unknown
B. Repair of fractures

1. Phases of simple fracture repair
a. Hematoma: clot of damaged vascular tissue
b. Fibrocartilaginous callus formation: soft callus
i. New vascular tissue
ii. Osteoblasts migrate and begin reconstruction
iii. Fibroblasts bring gap with collagen
iv. Osteoblast begin to form spongy bone
c. Bony callus formation: formation of woven bone
d. Remodeling

Axial Skeleton I
Skeleton is comprised of axial and appendicular structures.
I. Skeleton
A. Components
1. Bones
a. 206
2. Cartilage
3. Joints
4. Ligaments

B. Organization

1. Axial
a. Skull
b. Vertebral column
c. Rib cage
2. Appendicular
a. Limbs
b. Girdles that attach to axial
i. Shoulder and hip bones

II. Axial Skeleton—Skull
A. Skull Bones
1. Organization
a. Cranial
b. Facial
B. Cranial bones
1. Functions
a. Site for head muscle attachment
b. Encase brain and particular sense organs
C. Facial bones
1. Functions
a. Site for facial muscle attachment
b. Cavities for particular sense organs
i. Gustation
ii. Olfaction
iii. Vision

c. Framework for the face
d. Openings for air and food passage
e. Secure teeth
D. Sutures—connections (joints) between bones of skull
1. All bones of the skull except mandible
2. Cranial bone sutures

a. Coronal
b. Sagittal
c. Squamous
d. Lamboid
3. Sutures of facial bones are named based on name of bones that are connected

E. Organization of the skull
1. Cranial vault (calvaria; skullcap)
a. Forms the superior, lateral and posterior aspects as well as the forehead
2. Cranial base (floor)
a. Forms inferior aspect
b. Fossae—steps

a. Anterior
b. Middle
c. Posterior
3. Cavities
a. Cranial

i. Brain
b. Orbits
i. Eyeballs
c. Paranasal sinuses
i. Nasal cavity
d. Middle and inner ear
4. Openings
a. Foramina
b. Canals
c. Fissures

III. Bones of the Cranium

A Paired
1. Parietal
2. Temporal
B. Unpaired
1. Frontal
2. Occipital
3. Sphenoid
4. Ethmoid
C. Frontal bone

1. Structural contribution
a. Anterior portion of cranium
b. Roofs of the orbits
c. Anterior cranial fossa
2. Parts
a. Frontal squama
b. Supraorbital margins
c. Glabella
3. Articulations
a. Coronal suture
i. Parietal bones
b. Frontonasal suture

4. Sinuses and openings
a. Frontal sinus
b. Supraorbital foramen
D. Parietal bone
1. Structural contribution
a. Superior and lateral aspects of the skull
2. Articulations
a. Coronal
i. Anterior; frontal bone
b. Sagittal
i. Midline; parietal bones
c. Lamboid
i. Posterior; occipital bone
d. Squamous
i. Lateral; temporal bones
E. Occipital bone
1. Structural contribution
a. Posterior wall and base of skull
b. Walls of the posterior cranial fossa
2. Articulations
a. Lamboid
i. Parietal bones
b. Occipitomastoid
i. Temporal bones
c. Basioccipital

i. Sphenoid bone
3. Openings
a. Foramen magnum
i. Brain connects with spinal cord
4. Protrusions
a. Occipital condyles
i. Articulates with first vertebrae
F. Temporal bones
1. Structural contribution
a. Lateral surface
b. Inferior to parietal (inferolateral aspects of skull)
2. Articulations
a. Squamous
i. Parietal
3. Shape—complicated; 4 regions
a. Squamous
i. Zygomatic process meets zygomatic bone—zygotic arch
ii. Mandibular fossa and condyle of mandible—temporomandibular joint
b. Tympanic region
i. Surrounds external auditory meatus
ii. Styloid—needlelike projection; muscle attachment
c. Mastoid—mastoid process
i. Anchoring point for neck muscles
ii. Mastoid sinuses
d. Petrous region—mountain range

i. Cranial base
ii. Between occipital and sphenoid bones
iii. Middle cranial fossa
iv. Houses middle and inner ear cavities
4. Foramen
a. Jugular
i. Jugular veins; three cranial nerves
b. Carotid canal
c. Internal acoustic meatus
i. Cranial nerves VII and VIII
G. Sphenoid bone

1. Articulates with all other cranial bones
2. Shape
a. Central Body
b. Three pairs of processes
i. Greater wings
ii. Lesser wings
iii. Pterygoid

H. Ethmoid bone

1. Shape

a. Cribriform plate
b. Perpendicular plate
Axial Skeleton II and Appendicular Skeleton
I. Facial Bones: 14 Bones

A. Unpaired
1. Mandible
2. Vomer
B. Paired
1. Maxillae
2. Zygomatics
3. Nasals
3. Lacrimals
4. Palatines
5. Inferior conchae
C. Mandible: U-shaped lower jaw

1. Structure
a. Ramus (branch)
b. Body
2. Landmarks
a. Mandibular notch
b. Mandibular condyle (rounded articular projection)
c. Mandibular angle
d. Coronoid process
i. Attachment for temporalis muscle
e. Alveolar margin
i. Holds teeth
D. Maxillay bones (Maxillae): Upper jaw and central portion of facial skeleton

1. Keystone—all other facial bones articulate with maxillae
2. Landmarks
a. Aveolar margins
b. Palatine processes
i. Posterior projection
ii. Anterior 2/3’s of hard palate
c. Frontal processes
i. Superior projection to frontal bone
d. Zygomatic processes
i. Articualtions with zygomatic bones
E. Zygomatic bones: Cheek bones

1. Interolateral margins of orbits
F. Nasal bones
1. Bridge of nose
2. Articulations
a. Superior: frontal bone
b. Lateral: maxillae
c. Posterior: ethmoid bone
G. Lacrimal bones

1. Medial walls of each orbit
2. Articulations
a. Superior: frontal bones
b. Posterior: ethmoid bone
H. Palatine bones
1. Posterior part of the hard palate
I. Vomer: Nasal septum
J. Inferior nasal conchae
1. Part of the lateral wall of nasal cavity
K. Hyoid bone: Acts as moveable base for tongues

1. Not part of skull
2. Does not articulate with any other bones
3. Raise and lower larynx during swallowing

II. Vertebral Column (Spine)

A. General characteristics
1. 26 irregular bones
2. Transfers weight of trunk to lower limbs
3. Protects the spinal cord
4. Attachment point for ribs
5. Attachment point for muscles of back
B. Divisions (5)
1. Cervical curvature
a. 7 vertebrae (C 1-C7)
b. Concave posteriorly
2. Thoracic vertebrae
a. 12 vertebrae (T1-T12)

b. Convex posteriorly
3. Lumbar curvature
a. 5 vertebrae (L 1-L5)
b. Concave posteriorly
4. Sacrum: 5 fused vertebrae
a. Convex posteriorly
5. Coccyx: 4 fused vertebrae
C. Ligaments
1. Anterior and posterior ligaments
D. Intervertebral discs (shock absorbers)

1. Functions as a cushion-like pad between vertebrae

2. Two parts
a. Nucleus pulposus—semi-fluid
i. Gives elasticity and compressibility
b. Annulus fibrous
i. Forms outer collar to limit expansion
ii. Connects successive vertebrae
iii. Rupture: herniated disc (slipped disc)

E. General structure of vertebrae

1. Body (centrum)
2. Vertebral arch
a. Pedicle
b. Transverse process
c. Superior articular process
d. Laminae
e. Transverse process
f. Vertebral foramen
i. Successive foramen form vertebral canal
g. Intervertebral foramina
i. Spinal nerves pass through laterally

III. Thoracic Cage

A. Elements
1. Dorsal (posterior): Vertebrae
2. Lateral: Ribs
3. Anterior: Sternum and costal cartilages
B. Function
1. Protective cage for vital organs
2. Attachment for muscle
3. Supports shoulders girdle and upper limbs
4. Participates in breathing
B. Sternum (fusion of three bones)

1. Manubrium, body and xiphoid process
2. Articulations
a. Manubrium
i. Clavicles: clavicular notches
ii. First two pairs of ribs
b. Body (bulk of sternum)
i. Cartilages of ribs 2-7
c. Xiphoid
i. Body of sternum
3. Landmarks
a. Jugular notch
i. Common carotid artery issues from aorta
ii. Level of second and third vertebrae
b. Sternal angle
i. Level of second rib
ii. Disc between fourth and fifth thoracic vertebrae
c. Xiphisternal joint
i. Ninth thoracic vertebra
C. Ribs
1. Nomenclature based on Attachments
a. Posterior: thoracic vertebrae
b. Anterior
i. Vertebrosternal—True(7 pairs): sternum via intercostals cartilages
ii. Vertebrochondral—False (3 pairs): indirect attachment to sternum via costal
cartilage
iii. Vertebral—Floating (2 pairs): no anterior attachment

2. Size:
a. Increase from 1-7
b. Decrease from 8-12
3. Structure
a. Head of rib: articulates with same-numbered thoracic vertebra
b. Neck
c. Tubercle: articulates with transverse process of same-numbered thoracic vertebra
d. Shaft: bulk of rib

IV. Appendicular Skeleton
A. General characteristics
1. Limbs and girdles
2. Pectoral girdle: attaches upper limbs to body trunk
3. Pelvic girdle: attached lower limbs to body trunk
4. Limb fundamental plan
a. Three segments connected by moveable joints
B. Pectoral girdle (not really a girdle—not connected posteriorly)
1. Bones (2)
a. Clavicle
i. Anterior
b. Scapula
i. Posterior
2. Characteristics
a. Only clavicle attaches to thoracic
b. Scapula is free to move across thorax

i. Arm very mobile
c. Socket of shoulder joint (glenoid cavity of scapula)
i. Shallow and poorly reinforced
ii. Does not restrict movement of humerous
3. Clavicle—double curve

a. Sternal end
i. Articulates sternum (manubrium)
b. Acromial end
i. Articulates scapula
c. Function
i. Restricts medial movement of arms
ii. Attachment for thoracic and shoulder muscles

d. Fracture
i. Curvature promotes anterior displacement
4. Scapula

a. Structure (triangle; three sides and angles)
i. Acromion—anterior projection of spine; articulation with clavicle
ii. Coracoid process—anterior projection of superior scapular border; anchors
bicep muscle
iii. Glenoid cavity—articulates with humerous
iv. Suprascapular notch—nerve passage
v. Superior, lateral and inferior angles
vi. Spine—posterior surface
vii. Infraspinous, supraspinous and subscapular fossa—shallow depressions

viii. Superior, medial and lateral borders

V. Upper Limb (30 bones)

A. Arm: shoulder to elbow
1. Structure of the humerus

a. Head
b. Anatomical neck
c. Greater and lesser tubercles
i. Separated by intertubercle groove
d. Surgical neck (most likely site of fracture)
e. Deltoid tuberosity
i. Attachment site of deltoid muscle
f. Radial groove
i. Course of radial nerve
g. Condyles
i. Trochlea (medial): articulates with ulna
ii. Capitulum: articulates with radius

B. Forearm (antebrachium)
1. General considerations

a. Two parallel long bones: ulna and radius
b. Articulations
i. Proximal: humerus
ii. Distal: bones of wrist
iii. Radioulnar joints: radius and ulna both proximally and distally
2. Ulna: forms elbow joint with humerus; wide at proximal end, narrow at distal
a. Olecranon and coronoid processes
i. Grip trochlea of humerus to form a stable hinge joint
ii. At full extension, olecranon process locks to prevent hyperextension

b. Radial notch: articulates with radius
c. Head (wrist end): articulates with radius
d. Styloid process: attachment for wrist ligaments
3. Radius: narrow proximally, wide distally
a. Head (humerus end)
i. Superior surface articulates with capitulum of humerus
ii. Medial surface articulates with ulna
b. Radial tuberosity: anchors biceps muscle
c. Styloid process: attachment for wrist ligaments
C. Hand

1. Carpus: proximal structure of hand

a. Group of 8 bones (carpals) tied together with ligaments
b. Two irregular rows of four bones each
i. Proximal row: scaphoid, lunate, triquetral and pisiform
ii. Distal row: Trapezium, trapezoid, capitate and hamate
2. Metacarpus (5 wrist-like spokes)
a. No names; numbers (1-5) instead; 1 on thumb side
b. Articulations
i. Bases with carpals
ii. Heads with phalanges
3. Phalanges (fingers or digits): 14 bones
a. Numbered 1-5 beginning with pollex (thumb)
b. Distal, middle and proximal phalanges for each digit
c. No middle phalanx for pollex

VI. Pelvic Girdle
A. Paired coxal (hip) bones

1. Coxal bones unite anteriorly
2. Coxal bones unite with sacrum posteriorly
3. Regions of coxal bone (fused during childhood)
a. Ilium
b. Ischium
c. Pubis
B. Ilium: majority of the coxal bone

1. Body
2. Ala (winglike)
A. Superior margins—Iliac creasts
3. Posteriolateral surface
a. Attachment of gluteal muscle
C. Ischium: posteriorinferior part of hip bone
1. Ishial body
2. Ishial ramus
3. Ishial tuberosity (where we sit)
D. Pubis (pubic bone)
1. Superior and inferior rami
2. Body
3. Pubic crest

4. Pubic tubercle
5. Pubic symphysis—fibrocartilage joining two pubic bones

VII. Lower Limb

A. Thigh
1. Femur: largest, strongest bone in the body
a. Proximal articulation with hip
b. Distal articulation with tibia
c. Courses medially
i. Center of gravity
2. Structure of femur

a. Head
b. Fovea capitis
i. Ligamentum teres connects with acetabulum of coxal bone
c. Angled neck
i. Femur articulates with lateral aspect of pelvis
d. Greater and lesser trochanters
i. Muscle attachment sites
e. Intertrochanter line and crest
f. Gluteal tuberosity
g. Lateral and medial condyles
i. Articulate with tibia
h. Medial and lateral epicondyles
i. Muscle attachment
i. Patellar surface
i. Articulates with patella
3. Patellar

a. Sesamoid bone enclosed in tendon

B. Leg: two parallel bones connected by interosseous membrane; articulate with each other
proximally and distally (tibiofibular joints do not allow movement)

1. Tibia
a. Receives weight of the body from femur and transmits it to foot
b. Second strongest bone in body
2. Structure of tibia
a. Medial and lateral condyles
b. Tibial tuberosity
i. Patellar ligament attachment
c. Lacks muscle on anterior crest and medial surface
d. Medial malleolus
i. Medial bulge of ankle
e. Fibular notch
i. Distal tibiofibular joint

3. Fibula
a. Head—superior end
b. Lateral malleolus
i. Articulates with talus
ii. Lateral ankle bulge
C. Foot: segmented; lever-like; support

1. Tarsus—7 tarsal bones (corresponds to carpus of the hand)
a. Talus
i. Articulates with tibia and fibula
b. Calcaneus (heel)
i. Carries talus on its superior surface

ii. Tuber calcanei touches ground
iii. Calcaneal tendon attaches to posterior surface
c. Other bones
i. Cuboid
ii. Navicular
iii. Medial, intermediate and lateral cuneiform bones
2. Metatasus—5 small long bones (metatarsal bones)
a. Metatarsal 1-5
3. Phalanges—14 bones; smaller and less moveable than those of hand
Articulations
I. Classification of Joints
A. Structural classification
1. Based on material binding bones together and presence or absence of a cavity
2. Types
a. Fibrous
b. Cartilaginous
c. Synovial
B. Functional classification
1. Based on amount of movement permitted
2. Types
a. Synarthroses
i. Immoveable
b. Amphiarthroses
ii. Slightly moveable
c. Diarthroses

iii. Freely moveable

II. Characteristics of Joints
A. Fibrous
1. Joined by fibrous tissue only; no cavity
2. Most are synarthrotic
3. Types
a. Sutures (bones of skull)

i. Overlapping or interlocking bone edges
ii. Junction filled with connective tissue that penetrates into articulating bones
iii. Ossified in adults (synostoses)

b. Syndes moses: bones connected by a cord or sheet of fibrous tissue

i. Ligament or interosseous membrane
ii. Movement proportionate to length of connecting fibers
iii. Example: distal end of tibia and fibula (synarthrosis)

c. Gomphoses—peg-in-socket

i. Tooth

B. Cartilaginous joints—articulating bones connected by cartilage; no joint cavity

1. Types
a. Synchondroses—bar or plate of hyaline cartilage
i. Site for bone growth
ii. Become ossified and immoveable (synarthrotic)
iii. Epiphyseal plate connecting epiphysis and diaphysis regions of long bones
b. Symphysis
i. Articulating surfaces are covered with articulating cartilage
ii. Cartilage (hyaline) is fused to an intervening pad of fibrocartilage
iii. Shock absorption with little movement
iv. Amphiarthrotic joints—strong with flexibility
v. Intervertebral discs

C. Synovial joints

1. Articulating bones separated by a fluid cavity
2. Freely moveable diarthrotic joints
3. General structure
a. Articular cartilage
i. Covers opposing bones
ii. Shock absorption
b. Synovial cavity
i. Fluid filled (synovial fluid)
c. Articular capsule

i. Double-lined fibrous capsule
ii. Continuous with periostea of the articulating bones
iii. Inner synovial membrane line fibrous capsule internally
iv. Covers all non-hyaline internal joint surfaces
d. Synovial fluid
i. Occupies all free space
ii. Reduces friction between cartilages
iii. Weeping lubrication—load based release of synovial fluid into and out of
cartilage during movement
e. Reinforcing ligaments
i. Intrinsic (capsular)—thickened parts of fibrous capsule
ii. Extracapsular—outside capsule
iii. Intracapsular—deep to capsule
4. Other structural features
a. Fatty pads between fibrous capsule and synovial membrane
b. Articular discs (menisci)—fibrocartilage separating articulating surfaces of opposing
bones
5. Associated structures
a. Bursae—sacs of lubricant
i. Flattened fibrous sacs lined with synovial membrane with synovial fluid
b. Tendon sheath—elongated bursa surrounding a tendon
6. Factors affecting synovial joint stability
a. Shape of articulating surfaces
i. Shape determines type of movement but does not determine stability
ii. Bones usually “misfit”
b. Ligaments

i. Unite bones
ii. Direct and limit movement
iii. Joints comprised of only ligaments are not stabile
c. Muscle tone—major stabilizing factor
i. Tendons crossing joints are taut due to tone
ii. Sensory receptors monitor and maintain tone

III. Synovial Joint Movement
A. Background
1. Skeletal muscles have a minimum of two attachment points
a. Origin—immoveable bone
b. Insertion—moveable bone
2. Contraction across joint moves insertion towards origin
3. Directional terms
a. Monaxial—slipping or sliding
i. No axis
b. Uniaxial
c. Biaxial
d. Multiaxial
4. Types of movement
a. Gliding (simple)
i. Surfaces slip or glide over another similar surface
b. Angular—increase or decrease angle between bones
i. Flexion—decrease angle on sagittal plane
ii. Extension—increase angle on sagittal plane

iii. Abduction—away from midline
iv. Adduction—toward midline
v. Circumduction—movement describing a conical space
vi. Rotation—turn bone along its own long axis
vii. Supination and pronation—movement of radius and ulna; s. parallel; r. radius
over ulna
viii. Inversion and eversion—sole of foot medial or lateral
ix. Protraction and retraction—non-angular anterior and posterior movement in
transverse plane
x. Elevation and depression—lift body part superiorly
xi. Opposition—thumb

IV. Types of Synovial Joints

A. Categories
1. Plane—articulating surfaces are flat
a. Slipping and gliding
i. Intracarpal joints
2. Hinge—projection of one bone fits into the trough of another bone
a. Uniplanar movement
b. Flexion and extension only
3. Pivot—conical end of one bone fits into sleeve of another
a. Uniaxial rotation
4. Condyloid (knucklelike)—oval surfaces fit into complimentary concavity
a. Permits angular movement
5. Saddle

a. Greater movement than condyloid
b. Both concave and convex surface
6. Ball and Socket—spherical head articulates with cuplike socket
a. Multiaxial
b. Most freely moving

V. Glenoid joint

1. Stability reduced to permit free movement

2. Ball and socket

a. Humerus—ball
b. Glenoid—socket
i. 1/3 size of humeral head
ii. Deepened by rim of fibrocartilage (glenoid labrum)
3. Reinforcing ligaments
a. Coracohumeral
i. Thickens capsule
ii. Supports weight of upper limb
b. Glenohumeral (3)
i. Strengthen front of capsule
c. Transverse humeral

4. Muscles and tendons
a. Superstabilizer
i. Long head of biceps brachii
ii. Superior margin of glenoid, through joint cavity, to head of humerus
b. Rotator cuff (4 tendons)—encircles joint

VI. Coxal Joint (hip)

1. Good range of motion; movement in all planes; limited by ligaments and socket depth
2. head of femur articulates with cupped acetabulum of coxal bone
3. Socket depth incrased by acetabulum labrum
a. Fibrocartilage

b. Diameter smaller than femur head
i. Snug fit
4. Ligament—reinforce capsule; screw femur head into acetabulum
a. Iliofemural
i. V-shaped; anterior
b. Pubofemoral
i. Triangular; inferior
c. Ischiofemoral
i. Spiral posteriorly

VII. Knee Joint

A. Movement
1. Extension
2. Flexion
3. Rotation (limited)
B. Structure—three joints
1. Femoropetallar joint: patella to femur
2. Tibiofemoral joints (2)
a. Lateral
i. Semilunar cartilage (menisci)
b. Medial
C. Ligaments—extensions of quadriceps

1. Patellar ligament
2. Medial and lateral retinacula
D. Extracapsular ligaments—prevent hyperextension (do not know names)
E. Intracapsular ligaments—cruciate ligaments
1. Prevent anterior/posterior displacement of articulating surfaces
2. Anterior cruciate
a. Ant. intercondyle area of tibia and medial side of lateral condyle of femur
3. Posterior cruciate
a. Post. intercondyle area of tibia and lateral side of medial condyle of femur
F. Knee movements—slide, roll, spin

VIII. Elbow Joint

A. Movement—hinge joint
1. Flexion and extension
a. No rotation
B. Structure
1. Radius and ulna articulate with humerus
2. Hinge formed by trochlear notch of ulna
3. Capsule (limited) between humerus and ulna and surrounding head of radius
4. Side to side motion is prevented by collateral ligaments of ulna and radius

IX. Joint Injuries
A. Mechanical
1. Sprain

a. Mild sprains involve overstretching muscles
b. Severe sprains involve partial rupture of tendon, ligament and/or blood vessels

2. Dislocation (luxation)—bones forced out of normal position
a. Partial
b. Dislocation
B. Inflammatory and Degenerative
1. Bursitis—inflammation of bursa
a. Direct injury or friction
2. Tendonitis—inflammation of tendons
3. Arthritis—inflammatory disease of joints
a. Osteoarthritis—most common

i. Degenerative aging of articular cartilage
ii. Restricts movement but is not crippling
b. Rhematoid arthritis—chronic inflammatory disease
i. Autoimmune disease
ii. Begins as synovitis
iii. Membrane thickens into pannus
iv. Inflammatory cells in pannus release enzymes that erode cartilage
v. Scar tissue forms and connects bones
vi. Scar tissue ossifies
4. Gouty arthritis—uric acid crystallizes and gets deposited into soft tissue of joints
Lecture 12: Muscle I
Muscle and Muscle Tissue
I. Background
A. Muscle types
1. Skeletal
a. Striated
b. Voluntary
2. Cardiac
a. Striated
b. Involuntary
3. Smooth
a. Non-striated
b. Involuntary
B. Common features
1. Elongated cells—muscle fibers

2. Myofilaments
a. Actin
b. Myosin
3. Terminology
a. Myo and sacro
C. General functions
1. Movement
2. Maintain posture
3. Stabilize joints
4. Temperature homeostasis

II. Gross Anatomy of Skeletal Muscle
A. Muscles are organs comprised of:
1. Muscle fibers
2. Connective tissue
3. Blood vessels
4. Nervous tissue
B. Organization

1. Individual fibers are surrounded by endomysium
a. Areolar connective tissue
2. Multiple fibers are bundled as fascicles
3. Fascicles are bound by collagen sheath
a. Perimysium
4. Epimysium then surrounds all fascicles of an entire muscle
5. Deep fascia binds muscles into functional groups

III. Microscopic Anatomy
A. Terms
1. Sarcolemma—plasma membrane surface
2. Sarcoplasm—cytoplasm of muscle cells

3. Myofibrils—contractile elements of skeletal muscle
B. Striations

1. A bands—dark bands
a. Anisotropic—polarize light
2. I bands—light bands
a. Isotropic—nonpolarizing
3. H band (within A band)
a. Visible only in relaxed muscle
4. M line
a. Bisects H band
5. Z disc (membrane)

a. Midline in I band
C. Sarcomere—region of myofibril between two successive Z discs
1. Functional unit of skeletal muscle
D. Microfilaments (myofilaments) with in bands
1. Thick filaments
a. Run entire length of A band
b. Myosin
2. Thin filaments
a. Extend across I band and part of the way into A band
b. Actin
3. Z disc—protein sheet connecting myofibrils together
E. Ultrastructure and molecular composition

1. Thick filaments
a. Myosin
b. Rodlike tail terminates in two globular heads
c. Tail comprised of heavy meromysin
i. Polypeptide chains (2) interwoven
d. Head comprised of ends of heavy meromysin + light meromysin
e. During contraction heads (cross bridges) interact with thin myofilaments
2. Thin myofilaments
a. Actin
b. Comprised G (globular) actin
c. Double stranded helix
3. Regulatory proteins

a. Tropomyosin
i. Sprials around action
ii. Block myosin head binding sites during relaxed state
b. Troponin—polypeptide complex
i. Binds Ca2+ (TnC)
ii. Binds tropomyosin (TnT)
iii. Inhibitory protein that binds actin (TnI)

IV. Contraction of Skeletal Muscle
Sliding Theory of Contraction: during contraction, thin filaments slide past thick ones so that
actin and myosin filaments overlap to a greater degree
A. Overview

1. Prior to contraction
a. Cross bridges are disengaged
b. All bands distinct
2. Nerve impulse initiates contraction
3. Cross bridges engage
4. ATP splits
a. Energy used for swinging of cross bridges
5. Actin filaments pulled together
a. H zone and Z disc smaller or lost
6. I band reduced
7. Cross bridges disengage
8. Crossbridges and actin filaments return to original position

B. Specifics of contraction
1. During relaxed state
a. Ca2+ concentration in sarcoplasm is low
i. Ca2+ is stored in sacroplasmic tubules
b. Troponin
Lecture 13: Muscle II
I. Contraction of Skeletal Muscle
Sliding Theory of Contraction: during contraction, thin filaments slide past thick ones so that
actin and myosin filaments overlap to a greater degree
A. Overview
1. Prior to contraction
a. Cross bridges are disengaged
b. All bands distinct
2. Nerve impulse initiates contraction
3. Cross bridges engage
4. ATP splits
a. Energy used for swinging of cross bridges
5. Actin filaments pulled together
a. H zone and Z disc smaller or lost
6. I band reduced
7. Cross bridges disengage
8. Crossbridges and actin filaments return to original position

II. Specifics of Contraction
A. During relaxed state
1. Ca2+ concentration in sarcoplasm is low

a. Ca2+ is stored in sacroplasmic tubules
2. Troponin-tropomyosin complex attached to actin filament
a. Tropomyosin positioned to block myosin binding sites on actin filament
3. ATP and inactive ATPase bound to myosin head
a. Low energy configuration
i. Binding to actin is not possible
B. Events during contraction
1. Nerve impulse (afferent signal) from motor neuron generates action potential in nerve cell
a. AP propagated along sarcolemma and down T tubules
2. Myosin ATPase activated
a. ATP splits
i. High energy myosin-ADP complex
3. AP causes release of Ca2+ from sarcoplasmic reticulum
4. Ca2+ binds to troponin
a. Molecular shape of troponin changes
i. Tropomyosin is removed from binding site of mysosin on the actin filament
b. Myosin attaches to actin
5. Contraction: Potential energy stored in high-energy configuration is used to pivot myosin
head
a. Myosin head bends as it pulls on actin
b. ADP and inorganic phosphate are released from myosin
6. New ATP attached to myosin head
a. Cross bridge simultaneously detaches
b. Following death, no ATP and muscle fibers cannot relax
i. Rigor mortis
7. If no new impulse, Ca 2+ is pumped back into sarcoplasmic reticulum (SR)

a. Relaxation occurs
8. If Ca2+ present from additional impulse, cycle repeats
a. Myosin head “steps” to next binding site on actin

III. Regulation of Contraction

A. Neuromuscular junction—functional connection between somatic nervous system and
muscles
1. Motor neuron axons bifurcate to form multiple endings
a. Separate endings synapse with individual nerve fibers
i. Each nerve fiber synapses with only a single motor neuron
ii. Motor neurons can synapse with multiple nerve fibers

2. Synapse—site of communication between neuron and muscle (neuron to neuron in nervous
system)
a. Contact is not direct
i. Physical separation—synaptic cleft
b. Requires signal to be transduced into a chemical signal
i. Neurotransmitter
ii. ACh is NT at neuromuscular junction
3. Motor end plate—physical modification of sarcolemma whe re neuron synapses with fiber
a. ACh receptors located on motor end plate
B. Transduction events:
1. Nerve impulse from somatic NS
2. ACh released from pre-synaptic motor neuron
3. ACh binds to receptors
a. Na+ channels open
b. Inward depolarizing current initiates an action potential (see subsequent lectures on
neurophysiology)
c. ACh is enzymatically destroyed
i. Acetylcholinesterase
4. Action potential is propagated along sarcolemma and down T tubules
5. Ca2+ is released from SR (see above for resulting effects)
6. Ca2+ is removed by continuously active Ca2+ pumps
a. At low enough concentrations, contraction ceases
7. At the level of individual muscle fibers (cells), contraction is all or nothing
a. In response to threshold stimuli, action potentials are generated in a non-graded
fashion
8. Refractory period—cells must re-polarize before another AP can occur

IV. Contraction of Skeletal Muscle
A. Motor Unit—functional unit; a single motor neuron and all the muscle fibers it supplies
1. Distribution of fibers in a single motor unit is spread throughout a muscle
a. Stimulation of a single motor neuron weakly contracts entire muscle
B. Muscle twitch—response of a muscle to a single supra-threshold stimulus
1. Phases (3)
a. Latent phase (a few msec)
i. Onset of stimulus
ii. No measured contractile activity
iii. Excitation-contraction coupling
b. Contraction phase (10-100 msec)
i. Onset of shortening to peak contraction
ii. If pull greater than load, muscle shortens
c. Relaxation phase (10-100 msec)
i. Re-entry of Ca 2+ into SR
ii. Muscle tension gradually returns to zero
2. Temporal characteristics vary among muscles
C. Graded muscle responses—variation in degree of contraction
1. Gradation results from:
a. Altering stimulation frequency

b. Altering stimulus strength

2. Response to frequency of stimulation
a. Temporal (wave) summation
i. Strength of contraction increases with successive stimuli
ii. Muscles that are already contracted, contract further with additional Ca 2+
iii. If stimulation is delivered prior to relaxation, contraction s are summed
b. Tetanus: At sufficiently high frequencies, no muscle relaxation occurs and
contractions fuse into a smooth, sustained contraction
3. Motor unit summation—response to increasing stimulus intensity
a. Primary mechanism for increasing force of contraction
b. Multiple motor unit summation—Recruitment
c. At threshold stimulation, first muscle contraction occurs
d. As stimulus intensity is increased, additional motor units are activated
e. Maximal stimulus

i. Strongest stimulus that causes increased contraction
f. Accomplished by increased neural activation
4. Treppe—force of contraction increases during response to stimuli at the same strength
a. Result of increasing Ca2+ availability
b. Heat created during contraction increases efficiency of muscle enzymes
i. Warming up prior to athletic activity
5. Isotonic and Isometric contractions
a. Terms:
i. Muscle tension—force of contracting muscle on an object
ii. Load—reciprocal force exerted by the object
b. To move a load, muscle tension must be greater than load
c. Isotonic contractions—muscle changes in length and moves load
i. Concentric—muscle shortens and does work
ii. Eccentric—muscle contracts as it lengthens
iii. Concentric and eccentric contractions occur can occur at the same time
iv. Eccentric contractions put the muscle in position to contract concentrically
d. Isometric contractions—tension increases but the muscle length stays constant
i. Load greater than force
ii. Maintenance of posture
iii. Most real-life movements involve both isometric and isotonic contraction

V. Muscle Metabolism
A. ATP is the sole source of energy for contraction
B. Little ATP is stored but it is regenerated (recycled) rapidly
1. Direct phosphorylation of ADP by creatine phosphate

2. Anaerobic glycolysis
a. In the absence of oxygen, glycolytic products (pyruvic acid) are metabolized to lactic
acid producing additional small quantities of ATP
3. Aerobic respiration
a. 95% of ATP during light exercise
b. In presence of oxygen, products of glycolysis are broken down entirely with the
generation of significant amounts of ATP
4. Glycogen is the source of glucose for both aerobic and anaerobic metabolism

VI. Force, Velocity and Duration of Muscle Contraction
A. Force
1. Number of fibers contracting—more motor units recruited, greater the force
2. Relative size of the muscle—greater cross sectional area, greater the tension possible
3. Series-elastic elements—non-contractile structures of muscles
a. Movement requires:
i. Moveable structures
ii. Tightening of connective tissue coverings and tendons
b. Tension created at a molecular level is transferred to muscle cell surfaces and through
connective tissues that bundle fibers together and ultimately to muscle insertion
c. Internal tension (myofibers) is transferred to external tension (series -elastic elements)
to the load
4. Depth of muscle stretch
a. Optimum resting length is the length at which maximum force can be generated
i. Actin and myosin overlap such that sliding can occur over the entire length of
the actin filament
b. There is also an operational optimum for the whole muscle
i. 80% - 120% of normal resting length
B. Velocity and duration

1. Load—as load increases, velocity and duration decrease
2. Muscle fiber type characterized based on:
a. Speed of contraction—based on efficiency of myosin ATPases
i. Slow
ii. Fast

b. Pathway for ATP formation
i. Oxidative fibers—aerobic pathways
ii. Glycolytic fibers—anaerobic glycolysis
c. Based on a. and b., three categories
i. Slow oxidative fibers
ii. Fast oxidative fibers
iii. Fast glycolytic fibers

VII. Smooth Muscle
A. Anatomy of smooth muscle fibers
1. Small, spindle-shaped cells
2. Arranged in sheets of opposing fibers
3. Generally two sheets with fibers at right angles to each other
a. Longitudinal layer—parallel to long axis
b. Circular layer—around circumference
c. Alternating contraction of layers—peristalsis
3. Lack highly structured neuromuscular junctions
a. Varicosities
i. Diffuse junctions

4. Lack striations
5. Lower myosin to actin ratio than skeletal (1:13 vs. 1:2)
6. No troponin complex
7. No sarcomeres
a. Consecutive groups of fibers are organized in a spiral
B. Contraction of smooth muscle
1. Electrical communication between individual smooth muscle cells —gap junctions
a. Entire sheet responds to a single stimulus
2. Some tissue has pacemaker cells
a. Some are self-excitatory
3. Overview of process:
a. Actin and myosin slide (like skeletal)
b. Rising intracellular Ca2+ triggers contraction
c. Energized by ATP
4. Difference between smooth and skeletal
a. Ca2+ interacts with regulatory molecules not troponin (do not need to know details)
C. Characteristics of contraction
1. Slow, sustained and resistant to fatigue
2. Energy economy—ATP-efficient contraction
D. Regulation of contraction
1. Multiple neurotransmitters
a. Different types of nervous innervation with different NT’s
i. Sympathetic NS: norepinephrine
ii. Parasympathetic NS: ACh
b. NT’s have different effects

i. NE—inhibits contraction
ii. ACh—promotes contraction

Lecture 14: Muscles III
I. Comparison of Skeletal, Cardiac and Smooth Muscle
Characteristic
Location

Appearance

Connective Tissue

Sarcomere
T Tubules
Gap Junctions
Neuromuscular
Junctions
Regulation of

Skeletal
Attached to bones,
fascia and skin

Cardiac
Walls of heart

Smooth
Single-unit: visceral
organs
Multi-unit: Internal
eye muscles, large
airways and arteries
Single, non-striated,
uni-nucleate

Single, long,
cylindrical, striated,
multinucleate
Epimysium,
perimysium,
endomysium
Present
Present at each end
None
Present

Branching chains of
cells, uni-nucleate,
striated
Endomysium

Present
Present at on end
Intercalated discs
None

None
None
In single-unit
In multi-unit

Somatic NS;
voluntary

Autonomic NS,
intrinsic
(pacemaker),
hormones,
involuntary
SR, extracellular
fluid
Via troponin/actin
interactions

Autonomic NS,
hormones, local
regulation,
response to stretch

Contraction

Endomysium

Ca2+ Source

SR

Role of Ca2+

Via troponin/actin
interactions

Pacemakers
Nervous System

None
Excitation

Present
Excitation or
inhibition

SR, extracellular
fluid
Via
calmodulin/myosin
interaction
In single-unit
Excitation or
inhibition

Varies: slow to fast

Slow

Very slow

None

Yes

In single-unit

Strength of
contraction

Strength of
contraction

Stress-relaxation
response

Affects
Speed of
Contraction
Rhythmic
Contraction
Response to Stretch

increases
Aerobic or
anaerobic

Respiration

increases
Aerobic

Primarily anaerobic

II. Abnormal Muscle Function
A. Fatigue—progressive muscle weakness and fatigue
1. Failure to respond to external stimuli (i.e., NS activation)
2. Causes:
a. Depletion of nutrients, ATP and/or O 2
b. Buildup of lactic acid and/or CO 2
B. Abnormal contractions
1. Spasm—a sudden involuntary contraction of short duration
2. Cramps—painful spasmodic contraction of muscle fibers
3. Convulsion—violent tetanic contraction of entire muscle groups
4. Fibrillation—asynchronous contraction of individual muscle fibers resulting in flutter with no
effective movement
5. Tic—spasmodic twitching common in eyelid and facial muscles
C. Myalgia—pain in one or more muscles
D. Myositis—inflammation of muscle tissue
E. Poliomylitis—viral based destruction of motor neurons in the anterior horn of the spinal cord
1. Muscular dystrophy results from a loss of motor neural innervations
F. Muscular dystrophy—term that describes any hereditary myopathy that causes muscle
atrophy and degeneration (Polio is a muscular dystrophy)
1. Duchenne form
a. Sex-linked
i. Carried by females; expressed by males
b. Progressive loss of motor function

c. Onset during early childhood
i. 2-6 years old
2. Fascioscapulohumeral form
a. Affects muscles of face and shoulders
i. Expressed later in life
G. Myasthemia gravis—muscle weakness resulting from abnormalities in the neuromuscular
junction
1. Likely cause: reduced number of ACh receptors
2. Affects face and neck—swallowing, speaking, chewing, eye moveme nts
H. Tetanus—toxin of tetanus bacillus blocks ACh receptors

III. Muscle Mechanics
A. Lever systems

1. Levers are rigid bars that moves at a fixed point
a. Fulcrum—fixed point
b. Effort—applied force
c. Load—resistance
2. Levers provide mechanical advantage or disadvantage
a. Power lever—force (small) exerted over a relatively long distance
i. Mechanical advantage
ii. Large load over a small distance
b. Speed lever—small loads over large distances
i. Mechanical disadvantage
3. Types of levers
a. First-class

i. Load and effort are at ends, fulcrum in between
ii. Mechanical advantage or disadvantage depending on whether load or effort is
closer to fulcrum
iii. Lift head off chest
b. Second-class
i. Effort applied to one end, fulcrum at the other end and load is in between
ii. Mechanical advantage
iii. Standing on toes
c. Third-class
i. Effort applied at point in between fulcrum and load
ii. Always at a mechanical disadvantage
iii. Most muscles
iv. Force is lost, speed is gained

IV. Muscle Shape
A. Based on organization of fascicles
B. Types

1. Parallel
2.Pennate
a. Short
b. Attach to a central tendon
c. Uni, bi, and multi—to how many sides of the tendon do the fascicles attach
3. Convergent—broad origin converging to a single tendon
4. Circular—fascicles arranged in concentric rings

V. Interactions of Muscles
A. Classification

1. Prime movers (agonists)—provide the major force for a specific movement
2. Synergists—aid prime movers
a. Promote same movement
b. Reduce unnecessary movements
3. Antagonists—muscle that opposes prime mover
a. Generally relaxed during prime movement although often provide opposing
resistance
b. Can also be prime movers to return body to its original position
4. Fixators—type a synergist
a. Immobilize a bone or a muscle origin
b. Example: scapula

V. Criteria for Naming Muscles
There are about 650 skeletal muscles with 75 pairs that are involved in posture and general
body movement. Skeletal muscles are named according to a number of criteria, each of which
focuses on a particular structural or functional characteristic.
A. Location—bone or area of body with which the muscle is associated
B. Action
1. Flexor, extensor, abductus, etc.
C. Shape

1. Deltoid, trapezius, etc.
D. Relative size
1. Maximus, minimus, longus, etc
E. Point of attachment—origin and insertion points are included in name
1. Origin is always first
a. Sternocleidomastoid
F. Number of origins (divisions)
1. Biceps, triceps, quadraceps
G. Direction of muscle fibers
1. Oblique, tranversus, rectus (parallel to axis)

VI. Muscles of the Axial Skeleton

A. Muscles of the head—eyes, facial expression and mastication
1. Facial expression

a. Epicranius
i. Occipitalis
Origin: Occipital bone
Insertion: Galea aponeurotica
Action: Pulls scalp posteriorly
ii. Frontalis
Origin: Galea aponeurotica
Insertion: Skin of eyebrows
Action: Raise eyebrows; wrinkle forehead
b. Corrugator supercillii
Origin: Frontal bone

Insertion: Skin of eyebrow
Action: Draws eyebrows together; wrinkles forehead
c. Orbicularis oculi
Origin: Frontal and maxillary bones
Insertion: Tissue of eyelid
Action: Draws eyebrows downward (blink, squint)
d. Orbicularis oris
Origin: Maxilla and mandible (indirect)
Insertion: Muscles and skin at edge of mouth
Action: Closes lips; purses and protrudes lips (kiss)
e. Bucinator
Origin: Maxilla and mandible
Insertion: Orbicularis oris
Action: Draws corner of mouth laterally
f. Zygomaticus
Origin: Zygomatic bone
Insertion: Muscles and skin at edge of mouth
Action: Raises corners of mouth upwards
g. Platysma
Origin: Fascia of chest
Insertion: Lower margin of mandible
Action: Depress mandible
h. Risorius
Origin: Fascia of masseter
Insertion: Angle of mouth

Action: Draws lips laterally
i. Levator labii superioris
Origin: Zygomatic and maxilla
Insertion: Skin and muscle of upper lip
Action: Opens lips; flares nostril
j. Depressor labii inferioris
Origin: Mandible
Insertion: Skin and muscle of lower lip
Action: Draws lower lip downward

2. Mastication

a. Masseter
Origin: Zygomatic arch
Insertion: Angle of mandible
Action: Prime mover—jaw movement

b. Temporalis
Origin: Temporal fossa
Insertion: Coronoid process of mandible
Action: Closes jaw; retracts mandible (jaw closed at rest)

c. Pterygoids
i. Medial
Origin: Sphenoid; p. plate, med. surface
Insertion: Mandible
Action: Elevates jaw

ii. Lateral
Origin: Sphenoid; greater wing
Insertion: Condyle of mandible
Action: Protrudes mandible

d. Bucinator
Origin: Maxilla and mandible
Insertion: Orbicularis oris
Action: Draws corner of mouth laterally

3. Muscles that move the tongue

a. Extrinsic
i. Genioglossus
Origin: Mandible, internal surface
Insertion: Bottom of tongue, body of hyoid
Action: Protrudes tongue

ii. Hyoglossus
Origin: Hyoid
Insertion: Bottom and lateral aspects of tongue
Action: Depress tongue

iii. Styloglossus
Origin: Styloid process of temporal bone
Insertion: Bottom and lateral aspects of tongue
Action: Retracts tongue

B. Muscles of the neck
1. Muscles that move the hyoid bone

a. Insert on and either elevate or depress hyoid bone and larynx
b. Form floor of oral cavity
c. Suprahyoid—elevate

i. Digastric
Origin: Lower margin of mandible
Insertion: Hyoid
Action: Elevates hyoid

ii. Stylohyoid
Origin: Styloid process of temporal bone
Insertion: Hyoid
Action: Elevates hyoid

iii. Mylohyoid
Origin: Medial aspect of mandible
Insertion: Hyoid
Action: Elevates hyoid

iv. Geniohyoid
Origin: Inner surface of mandible
Insertion: Hyoid
Action: Superior and anterior movement of hyoid

d. Infrahyoid—depress hyoid
i. Omohyoid
Origin: Scapula
Insertion: Hyoid

Action: Depress hyoid

ii. Sternohyoid
Origin: Manubrium
Insertion: Hyoid
Action: Depress larynx

iii. Thyrohyoid
Origin: Thyroid cartilage
Insertion: Hyoid
Action: Depress hyoid

iv. Sternothyroid
Origin: Manubrium and clavicle
Insertion: Thyroid cartilage
Action: Pulls thyroid cartilage inferiorly

2. Muscles of the neck and vertebral column

a. Anterolateral
i. Sternocleidomastoid
Origin: Manubrium and clavicle
Insertion: Temporal bone
Action: Prime mover—head flexion

ii. Scalenes
Origin: Cervical vertebrae (transverse process)
Insertion: First two ribs
Action: Elevates ribs; flex and rotate neck

b. Intrinsic muscles of the back (superficial)
i. Splenius (capitis and cervicis)

Origin: Spinous process of C7-T6
Insertion: Temporal and occipital bones (capitis); C2-C4, transverse
process (cervicis)
Action: Extend head (group); rotate and bend head (individual)

c. Deep muscles of back: Erector spinae

Multiple origins and insertions
i. Iliocostalis
Origin: iliac crests (lumborum); inferior 6 ribs (thoracis); ribs 3-6 (cervicis)
Insertion: Angles of ribs (L & T); C6-C4 (C)
Action: Extend vertebral column; bend vertebral column when acting on
one side

ii. Longissimus
Origin: Transverse processes of lumbar through cervical vertebrae
Insertion: Vertebrae and ribs superior to origin; Temporal bone (C)
Action: L & T: Extend vertebral column; bend vertebral column when
acting on one side; C: extend head, turn face towards same side

iii. Spinalis
Origin: Spines of upper lumbar and lower thoracic vertebrae
Insertion: Spines of upper thoracic and lower cervical vertebrae
Action: Extend vertebral column

iv. Quadratus lumborum
Origin: iliac creat
Insertion: Upper lumbar vertebrae and 12 th rib
Action: Independent action: flex v. column laterally; Jointly: extend
lumbar spine

3. Muscles of the thorax
a. Intermediate back muscles—elevate and depress ribs

a. Thoracic cage
i. External intercostals—vertebral column to costachondral junction
Origin: Inf. Border of rib above
Insertion: Sup. Border of rib below
Action: Elevate rib cage (inspiration)

ii. Internal intercostals—sternum to angle of ribs
Origin: Sup. Border of rib below
Insertion: Inf. Border of rib above
Action: Depress rib cage (expiration)

iii. Thoracic diaphragm—floor of thoracic cavity

Origin: Inf. Border of rib cage and sternum
Insertion: Central tendon
Action: Prime mover of inspiration: Flattens and enlarges dimensions of
thorax

4. Muscle of anterior and lateral abdominal wall
a. Four paired flat muscles

i. Rectus abdominis—pubic crest to xyphoid process
Origin: Pubic crest and symphysis
Insertion: Xiphoid process and costal cartilages
Action: Flex lumbar region of vertebral column

ii. External oblique—outer surfaces of lower 8 ribs to linea alba
Origin: Outer surfaces of lower 8 ribs
Insertion: Linea alba
Action: Jointly: flex vertebral column; Individually: rotation and lateral
flexion

iii. Internal oblique—iliac creasr to cartilage of lower 3 ribs, linea alba and pubic
bone

Origin: Fascia connecting to lumbar spine; iliac crest
Insertion: Linea alba, pubic crest, last 3 ribs
Action: Jointly: flex vertebral column; Individually: rotation and lateral
flexion

iv. Tansverse abdominis—horizontal from 6 lower ribs, lumbar vertebrae, iliac
crest to linea alba and pubic bone
Origin: Inguinal ligament; fascia connecting to lumbar spine; iliac crest,
last 6 ribs
Insertion: Linea alba; pubic crest
Action: Compress abdominal cavity

5. Muscles of pelvic floor

a. Pelvic diaphragm—muscles closing pelvic outlet
i. Levator ani
ii. Coccygeus
b. Urogenital diaphragm
i. Deep transverse perineus
c. Superficial space
i. Ischiocavernosus
ii. Bulbospongiosus
iii. Superficial transverse perineus

Lecture 15: Muscles of the Appendicular Skeleton I
I. Muscles Stabilizing and Moving the Shoulder Girdle
A. General characteristics
1. Muscles closely associated with those of the upper arm
2. Insertions
a. All insert on scapulae
b. One (trapezius) also inserts on clavicle
3. Types of scapular movement
a. Elevation
b. Depression
c. Protraction (abduction)
d. Retraction (adduction)
e. Upward rotation
f. Downward rotation
B. Trapezius

a. Characteristics
i. Large triangular muscle of the superficial back
b. Origin
i. Occipital bone
ii. Ligamentum nuchae
iii. Spines of thoracic (1-12) and 7th cervical vertebrae
c. Insertion
i. Clavicle
ii. Scapular spine
iii. Acromion process
d. Function

i. Clavicular portion: raises scapula, clavicle and shoulder
ii. Scapular spine and acromion portion
iia. Middle fibers: retracts (adducts) scapula towards vertebral column
iib. Lower fibers: depresses and pulls scapula downward
e. Synergists
i. Levator scapulae
ii. Rhomboideus
C. Serratus anterior
a. Origin
i. Outer surface of ribs 1-8
b. Insertion
i. Vertebral border of scapula
c. Function
i. Protraction (abduction); upward rotation
D. Pectoralis minor

a. Origin
i. Sternal ends of ribs 2-5
b. Insertion
i. Coracoid process
c. Function
i. Pulls scapula anteriorly

II. Muscles Stabilizing Scapulohumeral Joint and Moving Upper Arm
A. Flexors
1. Pectoralis major

a. Characteristics
i. Large breast muscle over pectoralis minpr
b. Origin
i. Sternal manubrum
ii. Ribs 1-6
iii. Clavicle
c. Insertion
i. Lateral lip of humeral intertubercular groove
d. Function
i. Primary flexor and adductor
ii. Medial rotation
e. Synergists

i. Coracobrachialis
ii. Deltoid

B. Abductors
1. Deltoid (see prior figure)
a. Characterisctics
i. Large, thick, triangular muscle responsible for the roundness of shoulders
b. Origin (same as insertion of trapezius)
i. Clavicle
ii. Scapular spine
iii. Acromion process
c. Insertion
i. Deltoid tuberosity of humerus
d. Function
i. Adduction*
ii. Flexor
iii. Extensor
2. Supraspinatus (C below)
a. Origin
i. Supraspinator fossa of scapula
b. Insertion
i. Greater tubercle of humerus
c. Function
i. Assistant abductor
ii. Superior border of musculotendinous cuff

C. Extensors
1. Latissimus dorsi

a. Characterisctics
i. Wide triangular muscle of the lower back
b. Origin
i. Lower thoracic vertebrae
c. Insertion
i. Floor and medial wall of intertubercular groove of humerus
d. Function
i. Extension (e.g., swimming, rowing, climbing)

2. Teres major (assistant extensor)
a. Origin
i. Scapular lateral border
b. Insertion
i. Medial lip of intertubecular groove of humerus

D. Rotators (B above)
1. Subscapularis
a. Origin
i. Scapular subscapular fossa I (scapula)
b. Insertion
i. Lesser tubercle of humerus
c. Function
i. Chief internal and medial rotator
ii. Anterior border of musculotendinous cuff
2. Infraspinatus
a. Origin
i. Scapular infraspinator fossa
b. Insertion
i. Greater tubercle of humerus
c. Function
i. External or lateral rotator
ii. Upper posterior border of musculotendinous cuff
3. Teres minor
a. Origin

i. Lateral border of scapula
b. Insertion
i. Greater tubercle of humerus
c. Function
i. External or lateral rotator
ii. Lower posterior border of musculotendinous cuff

III. Muscles on Upper Arm and Moving Forearm at Elbow Joint
A. General characteristics
1. Originate on pectoral girdle and humerus
2. Insert on humerus, radius and ulna
3. Compartments
a. Anterior compartment: flexors
b. Posterior compartment: extensors
B. Anterior compartment: flexors
1. Biceps brachii

a. Origin
i. Long head: supraglenoid tubercle
ii. Short head: Scapular coracoid process
b. Insertion
i. Radial tuberosity (radius)
c. Function
i. Chief flexor of the arm at the elbow
2. Brachialis
a. Origin
i. Anterior, lower 2/3 of humerus
b. Insertion
i. Coracoid process of ulna

C. Posterior compartment: extensors
1. Triceps brachii

a. Origin
i. Long head: infraglenoid tubercle of scapula
ii. Lateral head: posterior lateral surface of humerus
iii. Medial head: entire posterior surface of humerus
b. Insertion
i. Ulnar olecranon process
ii. Olecranon bursa
c. Function

i. Chief extensor of arm at elbow joint

IV. Muscles of Forearm
A. General characteristics
1. Muscles originate on distal humerus and proximal radius and ulna
2. Muscles insert on carpals, metacarpals and phalanges
3. Bulk of muscle located in proximal forearm
4. Tendons start in distal forearm
5. Compartments
a. Anterior compartment
i. Flexors
b. Posterior compartment
i. Extensors
6. Tendons are held in place at the wrist by the flexor retinaculum
B. Anterior compartment: organized based on position relative to surface
1. Superficial: flexors at wrist

a. Origin: epicondyle of humerus
b. Insertions
i. Flexor carpi radialis: base of the 2 nd metacarpal
ii. Palmaris longus: palm aponeurosis (deep fascia)
iii. Flexor carpi ulnaris: carpals and 5 th matacarpal
2. Intermediate: flexor of digits
a. Origin
i. Epicondyle of humerus
ii. Ulnar and radial heads
b. Insertion
i. Flexor digitorum superficialis: middle phalanx, 2 nd – 5th finger (see B)
3. Deep: flexors of digits

a. Origin
i. Anterior shaft of ulna and radius
b. Insertions
i. Flexor digitorum profundus: distal phalanx, 2 nd – 5th finger
ii. Flexor pollicis longus: distal phalanx of pollex

C. Posterior compartment (see D)
1. Superficial: extensors of wrist joint and digits
a. Origin: common tendon that attaches to lateral humeral epicondyle
b. Insertions (extensors of wrist joint)
i. Extensor carpi radialis longus: base of 2 nd metacarpal

ii. Extensor carpi radialis brevis: base of 3 rd metacarpal
iii. Extensor carpi ulnaris: base of 5 th metacarpal
c. Insertions (extensors of digits)
i. Extensor digitorum: middle, distal phalanx, 2 nd – 5th finger
ii. Extensor digitorum minimi: middle, distal phalanx, 5th finger
2. Deep
a. Origin: posterior surface of ulna and radius
b. Insertions
i. Abductor pollicis longus (and brevis): base of 1st metacarpal
ii. Extensor pollicis longus (and brevis): distal (and proximal) phalanx of polis
iii. Extensor indicis: proximal phalanx of index finger

D. Supinator and pronators
1. Supinator: deep, posterior compartment
a. Origin
i. Lateral humeral eipcondyle
ii. Proximal lateral ulna
b. Insertion
i. Proximal lateral radius
2. Pronator teres: anterior compartment, superficial
a. Origin
i. Medial humeral epicondyle
ii. Ulnar coronoid process
b. Insertion
i. Lateral radius

3. Pronator quadratus: intermediate, anterior compartment
a. Origin
i. Anterior, distal ulna
b. Insertion
i. Anterior distal radius

V. Muscles of the Hand (Not responsible for these muscles)
A. Thenar muscles of thumb (4)
1. Abductor pollicis brevis
2. Flexor pollicis brevis
3. Opponens pollicis
4. Abductor pollicis
B. Hypothenar muscles of little finger (3)
1. Abductor digiti minimi
2. Flexor digiti minimi brevis
3. Opponens digiti minimi
C. Midpalmar muscles (3)
1. Lumbricals
2. Palmar interossei
3. Dorsal interossei
Lecture 16: Muscles of the Appendicular Skeleton II
I. Muscles that Stabilize and Move Thigh at the Hip
A. General characteristics
1. Movements
a. Flexion

b. Extension
c. Abduction
d. Adduction
e. Rotation (internal and external)
B. Anterior muscles

1. Primarily flexors
2. Iliopsaos
a. Major flexor of thigh
b. Compound muscle
i. Iliacus
ii. Psoas

c. Different origins
i. Iliacus: iliac fossa
ii. Psoas: transvers process of 12 th thoracic thru 5th lumbar vertebrae
d. Common insertion: lesser trochanter of femur
C. Posterior hip muscles
1. Primarily extensors, abductors and rotators
2. Three gluteal muscles

a. G. maximus
i. Origin: dorsal ilium
ii. Insertion: gluteal tuberosity of femur
iii. Action: chief extensor of thigh; raises body from sitting position; straightens
leg during walking

b. G. medius
i. Origin: lateral ilium
ii. Insertion: greater trochanter of femur
iii. Action: major abductor of the thigh
c. G. minimus
i. Origin: external surface of ilium
ii. Insertion: greater trochanter of femur
iii. Action: major abductor of the thigh
3. Tensor fascia latae
a. Origin: outer ant. iliac creast
b. Insertion: lateral condyle of tibia via iliotibia tract
c. Action: abductor
4. Six external rotators
a. Piriformis
b. Obturator externus
c. Obturator internus
d. Gemellus
i. Superior
ii. Inferior
e. Quadratus femoris
f. Origins: posterior portion of pelvis
g. Insertions: greater trochanter of femur
h. Actions: rotate thigh laterally and stabilize hip joint

II. Muscle of thigh moving leg at hip and knee joints

A. Medial compartment
1. Adductors

a. Adductor magnus
i. Origin: ischial and pubic rami
ii. Insertion: linea aspera and adductor tubercle of femor
iii. Action: adducts and laterally rotates
b. Adductor longus
i. Origin: pubis
ii. Insertion: linea aspera of femor
iii. Action: adducts and laterally rotates
c. Adductor brevis

i. Origin: pubic ramus
ii. Insertion: linea aspera of femor (above longus)
iii. Action: adducts and laterally rotates
2. Pectineus
a. Origin: pubis
b. Insertion: posterior aspect of femur
c. Action: adducts, flexes and rotates thigh
3. Gracilis
a. Origin: inf. ramus of pubis
b. Insertion: medial surface of tibia
c. Action: adducts thigh, flexes and rotates leg
B. Medial compartment
1. Quadriceps femoris (compound muscle)
a. Rectus femoris
b. Vastus lateralis
c. Vastus medialis
d. Vastus intermedius
e. Insertions: patella and tibial tuberosity via patellar ligament
f. Origins:
i. Vastus muscles: proximal anterior femur shaft
ii. Rectus femoris: anterior inf. iliac spine
g. Actions: chief extensor at knee
i. Rectus femoris: assistant flexor at hip
2. Sartorius
a. Origin: ant. superior iliac spine

b. Insertion: medial aspect of proximal tibia
c. Action: flexes and laterally rotates thigh

3. Posterior compartment: three hamstring muscles

a. Biceps femoris
i. Origins: ishial tuberosity (long head), distal femur (short head)
ii. Insertion: common tendon inserting into head of fibula and lateral condyle of
tibia
iii. Action: extends thigh, flexes knee, laterally rotates leg
b. Semitendinosus

i. Origin: ishial tuberosity
ii. Insertion: medial aspect of upper tibial shaft
iii. Action: extends thigh, flexes knee, medially rotates leg
c. Semimembranous
i. Origin: ishial tuberosity
ii. Insertion: medial condyle of tibia
iii. Action: extends thigh, flexes knee, medially rotates leg

III. Muscles of the Leg
A. General characteristics
1. Primary movements
a. Dorsal and plantar flexion
b. Inversion and eversion
B. Anterior compartment

a. Tibialis anterior
i. Origin: lateral condyle of tibia and upper tibial shaft
ii. Insertion: medial cuneiform and 1 st metatarsal
iii. Action: prime mover of dorsiflexion
b. Extensor digitorum
i. Origin: lateral condyle of tibia and proximal ¾ of fibula
ii. Insertion: 2nd and 3rd phalanges
iii. Action: dorsiflexion of foot; prime mover of toe extention

c. Peroneus (fibularis) tertius
i. Origin: distal anterior surface of fibula
ii. Insertion: lateral malleolus and 5 th metatarsal
iii. Action: dorsiflexes and everts foot
d. Extensor hallucis
i. Origin: anteromedial fibula shaft
ii. Insertion: distal phalanx of great toe
iii. Action: extends great toe; dorsiflexes foot
C. Lateral compartment
a. Peroneus longus
i. Origin: upper portion of fibula
ii. Insertion: medial cunneiform and 1 st metatarsal
iii. Action: plantar flexes and everts foot
b. Peroneus brevis
i. Origin: distal portion of anterior fibula shaft
ii. Insertion: 5th metatarsal
iii. Action: plantar flexes and everts foot
D. Posterior compartment: calf muscles
1. General characteristics
a. Chief plantar flexors of foot and toes
2. Superficial muscles: triceps surae and plantaris

a. Gastrocnemius
i. Origin: medial and lateral condyles of femur
ii. Insertion: calcaneus
iii. Action: plantar flexes foot
b. Soleus
i. Origin: superior tibia and fibula
ii. Insertion: calcaneus
iii. Action: plantar flexes ankle

c. Plantaris
i. Origin: posterior femur
ii. Insertion: calcaneus
iii. Action: plantar flexes foot and assists in knee flexion
3. Deep muscles
a. Flexor digitorum longus
i. Origin: tibial shaft
ii. Insertion: distal phalanx of 2nd thru 5th toes
iii. Action: plantar flexes and inverts foot
b. Flexor hallucis longus
i. Origin: fibular shaft
ii. Insertion: distal phalanx of great toe
iii. Action: plantar flexes and inverts foot
c. Tibialis posterior
i. Origin: upper portion of fibula and tibia
ii. Insertion: several tarsals and metatarsals
iii. Action: prime mover of foot inversion; plantar flexes ankle
d. Popliteus
i. Origin: lateral condyle of femur
ii. Insertion: proximal tibia
iii. Action: flexes and rotates leg medially
Neurophysiology
I. Background
A. Cell Types
1. Neurons

2. Glia
B. Subtypes
1. Differ based on their structure, chemistry and function
C. Relative distribution
1. 100 billion neurons (give or take 100 million)
2. 10 times as many glia as neurons
D. Functional significance
1. Neurons confer the unique functions of the nervous system

II. Cellular Structure of Neurons
A. Neurons contain the same basic structures as most other cells
B. Structure of animal cells

1. Cell body (soma)
a. 20 um in diameter
b. Surrounded by a membrane that separates the inside of the cell from the outside
i. 5 nm thick
2. Cellular contents
a. Everything within the cell membrane other than the nucleus is the considered
cytoplasm
3. Nucleus
a. Contain the chromosomes that confer the heritable material—DNA

b. Gene expression
i. DNA to Protein
ii. DNA (transcription) mRNA (translation) Protein
3. Ribosomes
a. Site where protein is made
4. Endoplasmic reticulum
a. Rough
i. Have ribosomes
b. Smooth
i. Transport completed protein to other cellular sites
5. Mitochondria
a. Site where metabolic functions are performed
6. Golgi apparatus
a. Post-translational modification of proteins
7. Neuronal membrane
a. Cannot understand the function of the brain without understanding the structure and
function of the membrane and its associated proteins
C. Unique features of neurons

1. Morphological regions
a. Cell body (soma or perikaryon)
b. Neurites
2. Types of neurites
a. Axons
b. Dendrites
3. Axons
a. Cell body usually gives rise to a single axon
i. Conducts nerve impulse from one neuron to the next
ii. Up to 1 meter in length
iii. Speed of the nerve impulse is a function of the diameter of the axon
4. Dendrites
a. Small
i. Rarely more than 2mm
b. Organized symmetrically
i. Antennae

c. Dendritic tree
i. Collective term for all neurites of a given neuron
D. Neural signals
1. Efferent
a. Away from the cell body
2. Afferent
b. Towards the cell body
E. Synapse

1. Site of neurotransduction
a. Electrical to chemical signal

2. Structural elements
a. Axon terminal
i. Site where axon comes in contact with another neuron
b. Presynaptic terminal
c. Postsynaptic terminal
i. Usually found on dendrite
d. Cleft
i. Space between the two sides of a synapse
3. Synaptic transmission
a. Process by which information is transferred from one side of the synapse to the other
b. Most adult vertebrate synapses are electrical
c. Electrical impulse that travels down the axon is converted to a chemical message
4. Neurotransmitter
a. Chemical signal
b. Different neurons use different types of neurotransmitters
5. Receptor
a. Specialized proteins responsible for detecting neurotransmitters
b. Involved in transduction of signal

III. Non-Neuronal Cells
A. Glia
1. Support neuronal function
2. Types
a. Astrocytes
i. Regulate extracellular space

ii. Remove neurotransmitters, restrict movement of neurotransmitter from
synapse, etc.
b. Oligodendrocytes (Schwann Cells)
i. Myelinating glia
ii. Wrap around the axons
iii. Insulation
iv. Myelin sheath (what holds a sword)
v. Node of Ranvier: where the myelin sheath is interrupted

IV. Functional Activity of Neurons
A. Electrical current created by the movement of ions
1. Properties of ions differ from those of electrons
a. Free electrons and more nearly at the speed of light
b. Electrons are good conductors and the air surrounding a wire is not
c. Ions in the cytosol of the nerve cell are less conductive than electrons
d. Fluid around neurons is also a conductor
2. Membranes are leaky
a. Current moving down an axon leaves passively
i. Like water in a leaky hose
3. Active process is needed to overcome passive current flow from neuron
a. Action potential
B. Properties of action potentials
1. Do not diminish
2. Fixed in size and duration (independent of the amount of current that evokes it)
3. All or nothing
C. Action potentials occur because of the properties of the neuronal membrane

1. Neuronal membrane is excitable
D. Functional states of a neuron
1. Rest
a. Neurons do not fire continuously
b. When not generating action potentials, neurons are at rest
c. Cytosol along the inside of the membrane has a negative charge relative to the
outside
2. Resting membrane potential
a. Difference in the electrical charge across the membrane
i. Difference is always negative
ii. Can be measured using an intracellular microelectrode
3. Action potential
a. Brief reversal of the resting membrane potential
b. Electrical signal created during action potential generation is the basic information
unit of the nervous system
i. Binary code (actually analogue)
c. Result from the flow of current across the membrane
i. Current is supplied by other neurons
4. Current plot

a. Potential x time
i. Hyperpolarization
ii. Depolarization
iii. Threshold

V. Properties that Make Action Potentials Possible
A. Three questions
1. How does the neuronal membrane at rest separate electrical charge?
2. How is this charge rapidly redistributed across the membrane during an action potential?
3. How does the impulse (action potential) travel reliably down the axon?

(Properties that make it possible for a neuron to separate charge when at rest are the same
factors that allow action potentials to occur and for that impulse to be propagated along the
axon.)

B. Resting membrane potential
1. Important considerations
a. Nature of the fluids on the two sides of the membrane
b. Structure of the neuronal membrane
c. Proteins that span the membrane
C. Cytosol and extracellular fluid
1. Fluids are aqueous
a. Water distribute charges unevenly
i. Oxygen attracts more negative charge than hydrogen
b. Water is held together by polar covalent bonds
i. An effective solvent for charged molecules
2. Ions
a. An atom or molecule with a net electrical charge
b. Types
i. Cation (+)
ii. Anion (-)
3. Ionic bond
a. Molecule held together by the electrical attraction of oppositely charged atoms
4. Charged portion of water has a greater attraction for the ions than they have for each other
a. Ionic bond is broken
D. Phospholipid membrane
1. Terms
a. Hydrophilic: water loving
i. Polar compounds and ions
2. Hydrophobic: water fearing

a. Nonpolar covalent bonds
i. Do not interact with water
3. Lipids
a. Water insoluble biological molecule
4. Phospholipid bilayer
a. Tail
i. Long chain of carbons
ii. Nonpolar
b. Head
i. Polar end
ii. Comprised of P plus 3 O's
5. Functional consequence
a. Tails arrange themselves in a bilayer
i. Tails do not like water
ii. Tails are inside
iii. Heads are outside
E. Proteins associated with the membrane
1. Background
a. Proteins are the product of gene expression
b. Type and distribution of protein molecule distinguish neurons from other cells
c. Resting and action potentials depend on the special proteins that span the lipid
bilayer
d. Protein chemistry
i. Primary structure: aa chain
ii. Secondary structure: certain types of organizations such as helices and sheets
result when certain aa's are combined in the primary structure

iii. Tertiary structure: individual protein molecules can fold and form a more
highly organized structure (e.g. globule)
iv. Quaternary structure: when different polypeptides combine to for a larger
molecule
2. Ion channels

a. Number of individual protein molecules organized to create a pore in the membrane
i. Membrane spanning protein
b. Diameter of the pore limits what can pass through the channel
c. Selectivity is also conferred by the nature of the amino acids that line the inside of the
pore
i. Positively charged amino acids will attract negatively charged ions

ii. Negatively charged amino acids will attract positively charged ions
d. Gating
i. Unique micro-environmental conditions that alter the selectivity of an ion
channel changes (e.g., when voltage changes)
ii. Only when the membrane is within a particular voltage range does the
channel open
e. Function
i. Permit and control movement of charged molecules across the neural
membrane
ii. Movement is selective: size, charge and environmental condition

F. Diffusion (One of two primary forces that create resting membrane potentials)
1. Net movement of ions from a higher concentration to a lower concentration
2. Ions will not pass through the membrane
a. Can diffuse through ion channels selective for that particular ion
3. Concentration gradient
a. Difference in concentration between one side and the other
b. Solute will move down its concentration gradient
4. Factors necessary for diffusion of ions across the neuronal membrane
a. Ion channel for that ion
b. Concentration gradient
5. Ions will flow down a concentration gradient

G. Electric field (One of two primary forces that create resting membrane potentials)
1. Ions can also move as a result of an electric field
2. Background

a. Opposite charges attract and like charges repel. (Na+ moves towards negative field
and Cl- moves towards positive field)
b. Anode
i. Positive pole of a battery
ii. Negative flow to here
c. Cathode
i. Negative pole of a battery
ii. Negative flow away
d. Electric current
i. Movement of charges
e. Electrical potential (voltage)
i. Difference in charge between the anode and the cathode
ii. Reflects the force exerted on a charged particle
f. Electrical conductance
i. Ease with which a charged particle can move
g. Resistance
i. Difficulty with which a charged particle can move
3. Factors necessary for charged particles to move across the neuronal membrane
a. Ion channel for that ion
b. A potential difference across the membrane

Example: K+ of differing concentration separated by a semi-permeable membrane. This
difference generates an electrical potential. The side with the higher concentration is negative.
If the ions were allowed to freely move, the movement will stop at some point, but not when
the concentrations are equal. As positive charges accumulate on one side, the positivity makes
it less attractive to positive ions-the potential charge across the membrane offsets the
concentration gradient. The point at which this occurs is known as electrochemical equilibrium.
This relationship is described by the Nernst equation.

In biological systems, there multiple ions involved, each governed by a separate permeability
factor. This relationship is described by the Goldman equation.

H. Equilibrium state
1. Diffusional and electrical forces are equal and opposite
2. For neurons, when these forces are balanced, the resting membrane potential is negative
(see below)

Overview:
1. Neuronal membrane acts as a barrier to charges
a. Permits generation of concentration gradients
b. Permits generation of electric fields
2. Membrane has ion channels that are selective for ions of different ions
a. Specific ions can move under particular condition

I. Sodium-potassium pump

1. Necessary for the inside of the neuron to become negative relative to the outside of the
neuron
2. Membrane associated protein
a. Transfers ions across the membrane at the expense of metabolic energy
i. 70% of all brain energy is consumed by this pump
3. Net movement of ions
a. 3 Na+'s from the inside to the outside
b. K+'s are moved into the neuron
4. Result
a. Both electrical and a concentration gradients are created
b. Na+ is greater outside
c. K+ is greater inside
d. More positive ions outside than inside
i. Inside of the neuron is negative relative to the outside

J. Control of ionic movement
1. K+
a. K+ wants to move out based on the difference in concentration
b. K+ is attracted to the relative negative charge inside the neuron
c. Balance of these forces creates the resting potential
2. Na+
a. Na+ wants to move in based on the difference in concentration
b. Na+ is attracted to the relative negative charge inside the neuron
c. Tightly gated Na+ channels prevent the movement of Na+
d. Channels will not open unless a certain voltage range exists
i. Threshold (see below)

VI. Action Potentials
A. Definition
1. Rapid reversal of the resting potential
a. For an instant the inside of the neuron becomes positive relative to the outside
B. Voltage versus time plot
1. Terms
a. Rising Phase
b. Overshoot
c. Falling Phase
d. Undershoot
e. Depolarization
i. Less negative

f. Threshold
i. Critical level of depolarization needed for an AP
g. Hyperpolarization
i. More negative
C. Permeability changes underlie the action potential

1. Selective increase in Na+ conductance coincident to the rising phase
a. Na+ is responsible to AP initiation
b. Positive feedback loop causes increased Na+ conductance
c. Na+ conductance slowly activates K+ conductance
d. Na+ conductance inactivates (see below)
2. Selective increase in K+ conductance coincident to the falling phase
D. Refractory periods
1. Absolute refractory period
a. Time period during which it is not possible to generate an AP

2. Relative refractory period
a. Time period during which additional depolarizing current is necessary to generate an
AP
3. Absolute and relative refractory periods are dependant on the properties of the ion channels
that are involved in the AP (see below)
E. Initiation of an action potential
1. At rest:
a. Na+ channels are closed
b. A concentration gradient and an electrical potential exist because of the Na+/K+
pump
c. K+ channels are closed but leaky
i. Diffusional and electrical forces in balance (K+ wants to stay and leave at the
same time)
2. Effect of opening Na+ channels
a. Na+ would move down its concentration gradient and towards the negative potential
b. Inside of the neuron becomes positive relative to the outside
c. Na+ influx accounts for the rising phase of the action potential
F. Falling phase of the action potential
1. Leaky K+ channels open
a. K+ leaves by flowing down its concentration gradient, away from the now positive
(inside) side of the membrane towards the more negative side of the membrane
G. Voltage gated Na+ channels
1. Highly selective for Na+
2. Opened and closed by changes in the electrical potential of the membrane
a. When the resting potential is changes from -65mV to -45mV
i. Channels opens
b. Channels inactivate (close) spontaneously after approximately 1msec (inactivate)
c. Cannot “de-inactivate” until the neuron returns to its resting membrane potential

i. Responsible for the absolute refractory period

H. Voltage gated K+ channels
1. Opening is delayed
a. Coincides with the closing of the Na+ channels
2. K+ channels do not inactive
3. K+ continues to flow out of the neuron until it reaches its ionic equilibrium
4. Voltage inside the neuron will briefly be hyperpolarized
a. Less negative than the resting potential
b. Relative resting membrane potential
i. Additional current (more depolarizing current) would be required to reach
threshold
Neurotransmission and Chemistry
I. Background
A. Sequence of events
1. Action potential generation (see Neurophysiology)
2. Propagation of action potential along axon
3. Intra-neuron communication

II. Propagation of Action Potential

A. Active process is required
1. Current not sufficient to generate an action potential is passively conducted
2. Current leaks across the axonal membrane
a. Magnitude of the voltage change decays
i. Exponential decay
ii. Decay increasing distance from the site that the current was introduced
3. Leakiness of the axonal membrane prevents effective passive transmission
B. Action potential occurs without decrement along the entire length of the axon
1. Action potential propagation is not passive
2. Action potentials have conduction velocity
a. Occurrence time differs as a function of distance from stimulation site
C. Mechanism involves the passive spread of current
1. Current created by inward movement of Na+ associated with action potential
2. Depolarizing stimuli (see below) locally depolarize the axon
a. Open voltage-gated Na+ channels

b. Cause the influx of Na+
3. Current flows passively down the axon
a. Depolarizes adjacent areas of the axon
i. Opens Na+ channels in those areas
D. Action potential can only propagate away from the source of the depolarizing current
1. Na+ channels inactivate
2. Do not "deinactivate" until the membrane returns to resting membrane potentials
E. Process
1. Na+ channels open in response to stimulus
a. Action potential at that site
2. Depolarizing current passively flows down the axon
3. Local depolarization causes adjacent Na+ channels to open and generate an action potential
a. Upstream Na+ channels inactivate
b. K+ channels open
i. Membrane repolarizes
ii. Membrane is refractory
4. Process is repeated in neighboring segment
a. Impulse is propagated
F. Site of action potential in vivo
1. Axon
2. Axon hillock
a. Small part of the soma where the axon originates
3. Function of the density of Na+ and K+ channels

Fuse Example:
1. Strike a match and light the fuse, like reaching threshold
2. As a fuse burns, it ignites the combustible material just ahead
3. It burns only in one direction

III. Conductance Velocity
A. Factors affecting velocity
1. Axon diameter
a. Direct relationship
i. Increase diameter, increase velocity
b. Physiologically limiting
2. Saltatory conduction
B. Saltatory conduction

1. Myelin
a. Function as insulation
i. Promotes movement of current down the axon
ii. Equivalent to increasing the thickness of the axonal membrane 100 fold
iii. Reduces membrane capacitance
iv. Rate of passive spread is inversely proportionate to membrane capacitance
v. Distance that the current spreads down the inside of the axon and causes an
AP is enhanced by myelin
b. Produced by glia
i. Schwann cells in the periphery
ii. Oligodendrocytes in the CNS
c. Nodes of Ranvier
i. Intermittent breaks in the myelin

ii. Site of action potential regeneration
2. Time for an action potential to occur is rate limiting
a. Eliminate action potentials
b. Impulse travels faster

IV. Events at Synapse
A. Background
1. Types of synapses
a. Electrical
i. Rare in adult mammalian NS
ii. Gap junction
iii. Current flows directly through a specialized protein molecule—connexon
iv. Distance between the two sides of the membrane is very small (5nM)
b. Chemical
i. Predominant type
2. Terminology
a. Neurotransmitter
i. Chemical used to communicate with the postsynaptic membrane
b. Active zone
i. Site of neurotransmitter release
c. Postsynaptic density
i. Contain neurotransmitter receptors
ii. Intercellular chemical messages converted into intracellular signal

iii. Occurs in the postsynaptic cell
d. Neurotransmitter receptor
i. Specialized protein molecules that bind the chemical signal
ii. Transduces chemical signal into an intracellular message
iii. Nature of response depends on receptor type
e. Synaptic vesicle
i. Membrane spheres containing neurotransmitter
B. Events at chemical synapse

1. Neurotransmitters are synthesized and stored in synaptic vesicles
a. Takes place in the golgi apparatus
b. Transported via secretory granules
2. Action Potential arrives at the axon terminal

a. Opens a voltage gated Ca 2+ channel
3. Intracellular Ca2+ concentrations signals the neurotransmitter to be released
a. Exocytosis
i. Process by which vesicles release their contents
b. Vesicles fuse with the active zone
c. Not known how Ca 2+ acts as the signal
4. Neurotransmitter diffuses across the synaptic cleft
a. Binds to its receptor on the postsynaptic membrane
b. Postsynaptic action depends on the nature of the receptor
i. Events are summed over time and space (see below)
5. Neurotransmitter inactivation
a. Information in the brain is based primarily on the frequency of the signal (#/sec)
b. The magnitude of the postsynaptic response needs to be in proportion to the
presynaptic signal
i. Preserves the integrity of the message
ii. Chemical message must be controlled
c. NT must be inactivated
i. Degradation
ii. Reuptake
iii. Diffusion
iv. Bioconversion

V. Neurochemistry
A. Background

1. Neurons in the human brain communicate primarily by the release of small quantities of
chemical messenger
a. Neurotransmitters
i. Interact with receptors on neuronal surfaces
ii. Alter the electrical properties of neurons
B. Information transfer occurs at synapses
1. Most synapses use chemical messages released from presynaptic axonic terminals
a. Released in response to depolarization of the terminal
b. Messages diffuse across the synaptic cleft
c. Bind with specialized receptors that span the postsynaptic membrane
d. Receptor binding of the chemical messages alters neuronal function
i. Electrical
ii. Biochemical
iii. Genetic
C. Chemical communication in the human brain depends on:
1. Nature of the presynaptically released chemical message
2. Type of postsynaptic receptor to which it binds
3. Mechanism that couples receptors to effector systems in the target cell
D. Nature of chemical messages
1. Criteria for classification as a neurotransmitter
a. Molecule must be synthesized and stored in the presynaptic neuron
b. Molecule must be released by the presynaptic neuron upon stimulation
c. Application of the neurotransmitter directly to the target cell must be shown to
produce the same effects as the response produced by the release of the
neurotransmitter from the presynaptic neuron

2. Few chemical substances meet these criteria
E. Classification
1. Size
a. Neuropeptides: 3-30 aa's (e.g., met-enkephalin)
b. Small molecule neurotransmitters
i. Individual amino acids (glutamate, aspartate, GABA, glycine, acetycholine)
ii. Biogenic amines (dopamine, norepinephrine, epinephrine, serotonin)
2. Neurons that use particular neurotransmitters
a. Cholinergic
b. Catecholinergic
c. Serotonergic
d. Amino acidergic
e. Other (neuropeptides, NO, etc.)
3. Many neurons release more than a single neurotransmitter
a. Dufferential release is base on the conditions that exist
F. Cholinergic neurons
1. Utilize acetylcholine (Ach-"vagus substance") as their neurotransmitter.
a. ACh is the neurotransmitter for:
i. Neuromuscular junction
ii. Preganglionic neurons of the sympathetic and parasympathetic PNS
iii. Postganglionic neuron of the parasympathetic PNS
iv. Basal forebrain and brain stem complexes
b. ACh is synthesized from acetyl coenzyme A and choline

i. Reaction is catalyzed by CAT-choline acetyl transferase
c. ACh is degraded in the synaptic cleft by acetylcholinesterase
G. Catecholaminergic neurons
1. Types
a. Dopamine
b. Norepinephrine
c. Epinephrine
2. Synthesized from the amino acid tyrosine
a. Each has a catechol group
3. Inactivated by reuptake
a. Substances that block their reuptake, prolong their activity
i. Cocaine
ii. Amphetamine
H. Serotonergic (serotonin) neurons
1. 5-hydroxytryptamine, commonly referred to as 5-HT
2. Inactivated by reuptake
3. 5-HTergic neurons appear to play a role in the brain systems that regulate mood, emotional
behavior, and sleep
a. Compounds like Prosak (SSRI)
i. Block reuptake
ii. Prolong activity in the synapse
I. Diffuse neuromodulatory system
1. Catecholaminergic and serotonergic neurons
2. Modulate large numbers of neurons

a. Spread diffusely throughout the nervous system
3. Use similar effector systems (see below)
4. Commonalities
a. Cell bodies for these neurons are localized to small populations of cell in the brain
stem
b. Each neuron can influence many others
i. Each axon makes a 100,000 or more synapses widely spread across the brain
c. Synapses are designed to release the neurotransmitter into the extracellular fluid
i. Allows the NT to spread and affect many neurons
5. Sites of dopamine action

a. System I
i. Cells bodies in the substantia nigra
ii. Regulates movement
b. System II
i. Cell bodies in the ventral tegmental area (VTA)
ii. Involved in reinforcement

6. Sites of serotonin action
a. Cell bodies are in the raphe nuclei
b. Involved in sleep, mood and emotional behavior
7. Sites of norepinephrine action
a. Cell bodies are in the locus coeruleus
b. Makes the most diffuse contacts of any neurons in the CNS
i. A single neuron can make 250,000 synaptic contacts in the cerebrum
ii. Have a second axon making another 250,000 contacts in the cerebellum
c. Contacts are non-specific
i. General regulation of brain activity
ii. Activity is coincident to state of CNS
8. Site of acetylcholine action
a. Basal forebrain
b. Neuromuscular junction (PNS)
J. Amino acidergic neurons
1. Types
a. Glutamate (Glu)
b. Glycine (Gly)
c. Gamma-aminobutyric acid (GABA)
2. Serve as the neurotransmitters at most CNS synapses
a. Glutamate is the primary excitatory neurotransmitter
b. GABA is the principle inhibitory neurotransmitter

VI. Transduction of Chemical Signals
A. Background
1. Chemical messengers are released from the presynaptic terminal in response to an impulse
traveling down the axon
a. Impulse is a unit of information
2. Information needs to be transferred to the postsynaptic neuron
3. Process of transferring information to the postsynaptic neuron is transduction
a. Neurotransmitter binds with a specific receptor protein in the postsynaptic
membrane that uniquely identifies the NT
4. A limited number of chemicals that serve as NT's
a. NT's have multiple receptors (sub-types) that bind them

(The binding of the NT by the receptor is like inserting a key into a lock; if it is the correct key, it
will cause conformational changes in the protein.)

B. Two major classes of receptors

1. Ligand-Gated Ion Channels (Ionotropic)
2. G-Protein-Coupled Receptors (Metabotropic)

C. Classification based on speed of chemical synaptic transmission
1. Types
a. Fast signal transduction
b. Slow signal transduction
2. Factors affecting speed
a. Diffusion of the chemical message across the synaptic cleft and bind with the receptor
b. The time it takes for the receptor to transduce the chemical signal into a functional
change in the postsynaptic neuron
3. Fast neurotransmission
a. Postsynaptic receptor is a transmitter-gated ion channel
i. Ion channels function much more rapidly than G-proteins
b. Rate limiting step is time of diffusion
i. Therefore rapid (2-5 msec)
4. Slow neurotransmission
b. Postsynaptic receptor is a G-protein-coupled receptor
i. Rate limiting step is time for G-proteins to elicit their effect
ii. 100’s of msec to days
D. Ligand-gated ion channels
1. Membrane spanning proteins that form a pore
a. Pore is closed
b. NT binds to the receptor
i. Receptor undergoes a conformational change
ii. Pores open

iii. Ions can now pass through (i.e., generate current)
2. Postsynaptic potentials
a. Excitatory postsynaptic potentials (EPSPs)
i. Bring the membrane potential toward threshold (depolarize)
ii. Cations in or anions out
b. Inhibitory postsynaptic potentials (IPSPs)
i. Move membrane potential away from threshold (hyperpolarize)
ii. Anions in or cations out
3. Effects are transient
a. EPSP's and IPSP's can be summed temporally and/or spatially
i. Effects be additive or subtractive
b. When enough EPSP's are summed:
i. Threshold is reached
ii. Action potential results
4. NT has a direct effect on receptor
a. Binding of the NT opens an ion channel
b. Causes a direct change in the membrane potential
E. G-Protein-coupled receptors
1. Process
a. NT is bound to a postsynaptic receptor
b. Receptor proteins activate small protein molecules, called G-Proteins
i. Found inside the postsynaptic neuron
c. G-Protein activates an "effector" molecule

2. Types of effector proteins
a. Ion channels in the membrane
b. Enzymes that synthesize second messengers
i. 2nd messengers can activate other enzymes in the cytosol
ii. Enzymatic action regulates ion channel function and alter cellular metabolism
3. Receptors linked to G-Proteins are referred to as Metabotropic Receptors
a. Can have widespread metabolic effects
Neuroanatomy and Neuroembryology
I. Terminology
A. Anatomical references

1. Anatomical structures can be divided into front and back
a. Front
i. Anterior
ii. Rostral
b. Back
i. Posterior
ii. Caudal
2. Anatomical structures can be divided into top and bottom

a. Superior
i. Dorsal (Posterior for bipeds)
b. Inferior
i. Ventral (Anterior for bipeds)
3. Anatomical structures can be divided into sides
a. Midline
b. Medial
i. Close to the midline
c. Lateral
i. Away from the midline
4. Relative position of anatomical structures
a. Ipsilateral
i. Structures localized to the same side
b. Contralateral
i. Structures localized to different sides
c. Proximal
i. Close to a fixed reference point
d. Distal
i. Distant to a fixed reference point
5. Anatomical structures can be sectioned along flat surfaces (planes)

a. Coronal (frontal)
i. Vertical plane dividing structure into anterior/posterior parts
b. Sagittal
i. Vertical plane dividing structure into right and left halves
ii. Midsaggital (median)
iii. Parasagittal
c. Horizontal (transverse)
i. Divides structure into superior and inferior
6. Longitudinal axis
a. Nervous system is organized along an anterior to posterior axis
b. Different regions of the brain have different longitudinal axis
i. Cerebellum is ventral to the forebrain axis but dorsal to that of the brain stem

Note: The nervous system is organized along an anterior to posterior axis with a fluid filled tube
running through the center. At the anterior end, the structure have enlarged with evolutionary
advancement and to accommodate for this enlargement, the brain has become distorted and
curved so that some structures are more difficult to assign anatomical references.

B. Nervous system terminology
1. Neural cell bodies are often organized in rows
a. Lamina
i. Row or layer of cell bodies separated from another row or layer by a layer of
axons or dendrites
ii. Parallel to structural surface
b. Column
i. Row of cells perpendicular to the surface of the brain
ii. Share a common function
2. Terms referring to neuron cell bodies found in CNS
a. Grey matter
i. Generic term for neurons in the CNS
b. Nucleus
i. Clearly defined mass of neuron cell bodies
c. Substantia
i. Less distinct borders than nuclei
d. Locus
i. Small but well defined mass of neuron cell bodies
3. Terms referring to neuron cell bodies found in PNS
a. Ganglion
i. Collection of neurons in the PNS
4. Terms referring to axons
a. White matter
i. Generic term for a collection of axons
b. Tract (projection)

i. Refers to CNS
ii. Set of axons, also known as fibers, that project from one structure a nd form
synapses on a second common structure
c. Nerve
i. Refers to PNS
ii. Bundle of axons either projecting from the CNS to a muscle or gland or from a
sense organ to the CNS
d. Bundle
i. Collection of axons that run together but do not necessarily share the same
origin or destination
e. Commissure
i. Any collection of axons that connect one side of the brain with the other side
5. Terms that refer to the external morphology of the brain
a. Surface convolutions
i. Gyrus: ridge on the surface of the cerebrum (and cerebellum)
ii. Sulcus: groove
iii. Fissure: a deep groove
6. Important sulci and gyri

a. Central sulcus
i. Separates frontal (anterior) and parietal lobes (posterior)
b. Precentral gyrus
i. Commonly known as the motor cortex
c. Postcentral gyrus
i. Somatosensory cortex
d. Sylvian (lateral) fissure
i. Separates temporal and frontal lobes
ii. Temporal is inferior to the frontal and extends to the caudally located occipital
lobe
iii. Parietal lobe is superior to lateral fissure
e. Insula
i. Fold created by the temporal lobe
ii. Commonly referred to as the operculum
f. Parieto-occipital sulcus
i. Extends from superior to inferior surface

ii. Divides parietal from occipital lobes
g. Calcarine sulcus
i. Medial surface of the occipital lobe
ii. Defines the location of the visual cortex
h. Cingulate sulcus
i. Medial surface of the frontal and parietal lobes
ii. Inferior to this sulcus is the limbic lobe

C. Organization of the nervous system
1. Functionally organized into two divisions
a. Central nervous system (CNS)
i. Brain (Cerebellum, cerebrum and brain stem)
ii. Spinal cord
b. Peripheral nervous system (PNS)
i. Somatic
ii. Autonomic
2. Organization of gray and white matter
a. CNS
i. Gray matter is organized on the surface of the brain in lamina
ii. White matter is organized centrally
iii. White matter constitutes the majority of brain mass
b. PNS
i. Gray matter is centrally located
ii. White matter is organized on the surface

II. Cerebral Hemispheres
A. General characteristic of the cerebral hemispheres
1. Organized into functional areas
a. Motor
i. Voluntary control of movement
b. Sensory
i. Conscious awareness of sensation
c. Association
i. Integration
ii. Emergent properties
2. Contralateral control of the body
a. Each hemisphere is concerned with the opposite of the body
3. Functions are lateralized
a. Each hemisphere has unique functions
4. Function arises from concerted activity
5. Lobes

a. Frontal
b. Parietal
c. Temporal
d. Occipital
B. Motor areas
1. Cortical areas involved in movement
a. Primary motor cortex
b. Premotor cortex
c. Broca’s area
d. Frontal eye field
2. Primary motor cortex (Brodmann 4)
a. Located in the precentral gyrus of frontal lobe
b. Conscious control of motor execution
c. Pyramidal cells give rise to the corticospinal tracts
d. Somatotopy

i. Body is mapped (motor homunculus)
ii. Representation is proportionate to level of motor control
iii. Innervation is primarily contralateral
3. Premotor cortex (Brodmann 6)
a. Learned motor skills
i. Patterned or repetitious
4. Broca’s area (Brodmann 44/45)
a. Directs muscles of the tongue, throat and lips
b. Motor planning for speech related activity
5. Frontal eye field (Brodmann 8)
a. Voluntary movement of the eyes
C. Sensory areas
1. Cortical areas involved in processing sensation
a. Primary somatosensory cortex
b. Somatosensory association area
c. Visual cortex
d. Auditory cortex
e. Olfactory cortex
f. Gustatory cortex
2. Primary somatosensory cortex (Brodmann 1, 2 & 3)
a. Parietal lobe
i. Postcentral gyrus
b. Somatic senses
i. Pain and temperature
ii. Touch and proprioception

c. Somatotopy

i. Body is mapped (somatosensory homunculus)
ii. Representation is proportionate to number of sensory receptors
iii. Innervation is primarily contralateral
3. Somatosensory association area (Brodmann 5 & 7)
a. Integrate various somatic sensory inputs
4. Visual areas
a. Primary visual cortex (Brodmann 17)
i. Occipital lobe
ii. Located primarily in the calcarine sulcus
iii. Sensory function with largest cortical representation
iv. Innervation is primarily contralateral
b. Visual association areas (Brodmann 18 & 19)
i. Interpretation of visual stimuli
ii. Past visual experiences
5. Auditory areas

a. Primary auditory cortices (Brodmann 41)
i. Superior margin of temporal lobe
ii. Pitch, rhythm and loudness
b. Auditory association area (Brodmann 42 & 43)
i. Recognition of stimuli as specific auditory experiences (e.g., speech)
6. Olfactory cortex
a. Medial aspects of temporal lobe
i. Piriform lobe (uncus)
7. Gustatory cortex (Brodmann 43)
a. Parietal lobe deep to the temporal lobe

D. Association areas
1. Characteristics
a. Analyze, recognize and act on sensory in puts
b. Multiple inputs and outputs
2. Association areas (in addition to those discussed above)
a. Prefrontal cortex
b. Gnostic area
c. Language areas
3. Prefrontal cortex (Brodmann 11 & 47)
a. Anterior portion of frontal lobe
b. Intelligence, complex learned behavior and personality
c. Understanding written and spoke language
4. General interpretation area
a. Encompasses parts of temporal, parietal and occipital lobes

i. Generally found on the left side
b. Storage of complex sensory memories
5. Language areas
a. Bilaterally located
b. Wernicke’s area
i. Posterior temporal lobe on left side
ii. Sounding out unfamiliar words
c. Affective language areas
i. Located contralateral to Broca’s and Wernicke’s areas
ii. Nonverbal and emotional components of language
E. Organization of the cortex
1. Common features
a. Cell bodies are arranged in sheets (layers)
i. Parallel to surface of brain
b. Layer I lacks cell bodies
i. Molecular layer
c. At least one layer has pyramidal cells
i. Emit large apical dendrites
ii. Extend up to layer I
2. Cytoarchitecture
a. Lamina
i. Layers of cells parallel to brain surface
b. Columns
i. Row of cells perpendicular to brain surface
ii. Share a common function

3. Neocortical layers
a. Layer I
i. Few cells; primarily axons, dendrites and synapses
b. Layers II & III
i. Pyramidal cells that project to and receive projections from other cortical
regions
c. Layer IV
i. Stellate cells that receive most of thalamic input and project locally to other
lamina
d. Layer V & VI
i. Pyramidal neurons that project to subcortical regions such as the thalamus,
brainstem, and spinal cord, and other cortical areas

III. Subcortical Structures
A. Basal nuclei (ganglia)

1. Structures
a. Caudate
b. Putamen
c. Globus pallidus
2. Organization
a. Receive inputs from most cortical structures
b. Project to motor cortex via the thalamus
3. Function
a. Motor control
i. Starting, stopping and monitoring movement
ii. Inhibit unnecessary movement
B. Diencephalon

1. Organization
a. Core of forebrain
i. Surrounded by cerebral hemispheres
b. Three bilateral structures
i. Thalamus
ii. Hypothalamus
iii. Epithalamus
2. Thalamus
a. Comprised of multiple nuclei
i. Each nucleus receives specific afferent projections
ii. Nuclei interconnect
iii. Nuclei project (relay) processed information to particular cortical areas
b. Process and relay information
3. Hypothalamus
a. Location

i. Between optic chiasm and mammillary bodies
ii. Below thalamus
b. Connected to the pituitary
i. Via infundibulum
c. Visceral control center of the body
i. Autonomic control (e.g., BP, HR)
ii. Emotional response (e.g., fear, sex drive)
iii. Regulation of body temperature
iv. Regulation of feeding
v. Regulation of thirst
vi. Regulation of circadian rhythm
vii. Control of endocrine function
4. Epithalamus
a. Pineal body
i. Control of sleep-cycle
ii. Melatonin
b. Choroid plexus
i. Production of cerebral spinal fluid (CSF)

IV. Brain Stem

A. Organization
1. Functional areas
a. Midbrain
b. Pons
c. Medulla oblongata
B. Functions
1. Autonomic behavior
2. Pathway for fiber tracts
3. Cranial nerves
C. Midbrain
1. Structures
a. Cerebral peduncles
i. Fiber tracts connecting cerebrum with inferior structures
b. Corpora quadrigemina
i. Superior and inferior colliculi

c. Substantia nigra
i. Color is due to melanin (DA precursor)
ii. Nucleus of DA neurons
d. Red nucleus
i. Motor reflex
e. Reticular formation
i. Some of the RF nuclei are found here (see below)
D. Pons
1. Lies between midbrain and medulla
2. Comprised mostly of conducting fibers
a. Connection between higher brain areas and spinal cord
i. Longitudinal projections
b. Pontine nuclei
i. Relay information between motor cortex and cerebellum
3. Nuclei for several cranial nerves
a. Trigeminal (V)
b. Abducens (VI)
c. Facial (VII)
E. Medulla oblongata
1. Lies between pons and spinal cord
a. No obvious demarcation between medulla and spinal cord
2. Landmarks
a. Pyramids
i. Descending corticospinal tracts
ii. Decussate

3. Nuclei for several cranial nerves
a. Hypoglossal (XII)
b. Glossopharyngeal (IX)
c. Vagus (X)
d. Accessory (XI)
e. Vestibulocochlear (VIII)
4. Control of visceral motor function
a. Cardiovascular center
i. Cardiac center
ii. Vasomotor center
b. Respiratory center
i. Control rate and depth of breathing
c. Reflex
i. Vomit
ii. Hiccup
iii. Swallowing
iv. Coughing
v. Sneezing

V. Cerebellum
A. Anatomy
1. Location
a. Dorsal to pons and medulla
b. Caudal to occipital lobe
2. Structure

a. Bilateral
b. Consists of cerebellar hemispheres
i. Connected by vermis
c. Hemispheres consists of lobes
i. Posterior
ii. Anterior
iii. Flocolonodular
d. Gray and white matter is organized like cerebrum
i. Gray outside/white inside
e. Cerebellum is connected via cerebellar peduncles
i. Fiber tracts connecting brain stem and sensory cortices with cerebellum
B. Function
1. Precise timing of skeletal contraction
a. Sensory and motor information is integrated
VI. Brain Systems
A. Limbic system
1. Group of cortical structures
a. Located on medial aspect of the cerebral hemisphere and diencephalon
b. Connectivity is complex
2. Structures
a. Upper part of brainstem
b. Rhinencephalon
i. Septal nuclei
ii. Cingulate gyrus
iii. Parahippocampal gyrus

iv. Hippocampus
c. Amygdala
d. Diencephalon structures
i. Hypothalamus
ii. Anterior nucleus of the thalamus
e. Fiber tracts
i. Fornix
ii. Fimbria
3. Function
a. Emotional and affective state
B. Reticular formation
1. Complex of nuclei and white matter
a. Disperse and widespread connectivity
2. Location
a. Central core of medulla, pons and midbrain
3. Function
a. Maintain wakefulness and attention
i. Coordination of all afferent sensory information
b. Coordination of muscle activity
i. Modulation of efferent motor information

VII. Protection of the Brain
A. Primary mechanism
1. Bone
a. Brain is encased in a bony skullcap

2. Membranes
a. Meninges
3. Fluid
a. Cerebrospinal fluid
b. Blood-brain barrier
B. Meninges

1. Structure
a. Three connective tissue membranes
i. Dura mater (tough mother)

ii. Arachnoid mater (spider mother)
iii. Pia mater (gentle mother)
2. Dura
a. Two fused layers
i. Periosteal layer
ii. Meningeal layer
b. Periosteal layer is attached to the skull
i. Spinal cord does not have a periosteal layer
c. Meningeal layer covers brain and spinal cord
d. Dura projects inward to help anchor the brain
e. Dural septa
i. Falx cerebri
ii. Falx cerebelli
iii. Tentorium
f. Dural sinuses
i. Spaces between dural layers
ii. Collect venous blood flow from brain
iii. Directs blood flow back to jugular veins
3. Arachnoid
a. Loose cover over brain
i. Does not enter sulci
b. Small space between dura and arachnoid
i. Subdural space
c. Subarchnoid space
i. Deep to arachnoid

ii. Filled with CSF
iii. Secured to pia by weblike extensions of the arachnoid
d. Arachnoid villi
a. Act like valves
b. Projection of archoid through dura into dural sinuses
c. Permits CSF to be absorbed into venous blood
4. Pia
a. Clings tightly to brain
b. Invested with blood vessels

C. Cerebrospinal fluid (CSF)
1. Function
a. Form a liquid cushion for CNS organs
b. Provides nutrients
c. CSF composition is monitored
i. Control of autonomic functions
2. Found in ventricles (see below) and central canal of spinal cord
3. Choroid plexuses
a. Produce CSF
b. Located in ventricles
4. Flow
a. Produced in ventricles
b. Exit 4th ventricle
c. Bath brain
d. Absorbed into venous blood through arachnoid villi

5. Anatomy of the ventricular system

a. Four fluid-filled chambers
i. Paired lateral
ii. Third
iii. Fourth
b. Chambers are continuous with each other and with the central canal of the spinal
cord
c. Interventricular foramen connect lateral with third
d. Third is connected with fourth via cerebral aqueduct
e. Fourth is continuous with central canal
f. Fourth has openings to subarachnoid space
i. Lateral apertures
ii. Median aperture

D. Blood-brain barrier

1. Brain environment is tightly controlled
a. Most bloodborne substances cannot readily enter the brain
2. Mechanism
a. Capillary endothelium is joined by tight junctions
i. Relatively impermeable
3. Barrier is selective
a. Facilitated diffusion of particular substances
i. Glucose and others
b. Cannot prevent fat-soluble molecules from diffuses into brain

VIII. Spinal Cord
A. Gross anatomy

1. Protected
a. Bone
i. Vertebral column
b. Membranes
i. Meninges
c. Fluid
i. CSF
2. Meninges

a. Single layer
i. Spinal dural sheath
b. Epidural space
i. Padding of fat between vertebrae and dural sheath
c. Subarachnoid space
i. Filled with CSF
d. Extend to S2
i. Spinal cord only extends to L 1
3. Attachments
a. Denticulate ligaments
i. Attached to vertebrae laterally
b. Filum terminale
i. Attached to coccyx caudally
B. Cross-sectional anatomy

1. Meninges

a. Dura
b. Arachnoid
c. Pia
2. Gray matter and spinal roots
a. Gray is organized like a butterfly
i. Bridge—gray commissure
b. Gray matter columns
i. Posterior (dorsal) horn
ii. Anterior (ventral) horn
iii. Lateral horn (thoracic and superior lumbar regions only)
3. Anterior horn
a. Cell bodies of somatic motor neurons
b. Send axons via ventral root
4. Lateral horn
a. Cell bodies for autonomic motor neurons
i. Sympathetic NS
b. Leave via ventral root
5. Dorsal root ganglion
a. Cell bodies of sensory neurons
b. Axons project to cord via dorsal root
i. Some enter white matter tracks and ascend
ii. Some synapse with interneuron located in posterior horn
6. Spinal nerves
a. Lateral fusion of ventral and dorsal roots
b. Part of PNS (see below)

C. Spinal pathways

1. Characteristics
a. Most pathways decussate
b. Most are poly-synaptic
i. Two or three neurons
c. Most are mapped
i. Position in cord reflects location on body
d. All pathways are paired
2. Ascending (sensory) pathways (see sensory systems)

a. Dorsal column (fasciculi cuneatus and gracilis)
i. Touch and proprioception
b. Spinothalamic (anterior and lateral)
i. Pain and temperature
3. Descending (motor) pathways (see motor lecture)
a. Upper motor neurons
i. Cell bodies in brain
b. Lower motor neurons
i. Cell bodies in anterior horn of spinal cord
c. Direct
i. Anterior and lateral (pyramidal) corticospinal tracts
d. Indirect (tracts)—multi-neuronal
i. Rubrospinal
ii. Vestibulospinal
iii. Reticulospinal
iv. Tectospinal

IX. General Organization of the Peripheral Nervous System
A. Background
1. Function
a. Connect brain with outside world
i. CNS function is dependent on information
2. Structural components
a. Sensory receptors
b. Peripheral nerves and ganglia

c. Efferent motor endings
B. Sensory receptors
1. Nature of stimulus detected
a. Mechanoreceptors
i. Touch, vibration, pressure, stretch
b. Thermoreceptors
i. Temperature changes
c. Photoreceptors
i. Light energy
ii. Exclusively in the retina
d. Chemoreceptors
i. Chemical in solution
e. Nociceptors
i. Pain
2. Location
a. Exteroceptors
i. Surface of skin
b. Interoceptors
i. Visceroceptors
ii. Visceral organs and blood vessels
c. Proprioceptors
i. Musculoskeletal organs
3. Complexity
a. Simple
i. Most sensory receptors (generalized)

b. Complex
i. Special senses (vision, audition, olfaction, gustation)
4. Generalized sensory receptors
a. Free dendritic endings (unencapsulated)
i. Free
ii. Merkel discs
iii. Root hair plexus
b. Encapsulated
i. Meisner’s corpuscles—low frequency vibration)
ii. Pacinian corpuscles—high frequency
iii. Ruffini’s corpuscles—deep pressure
iv. Muscle spindles—muscle stretch
v. Golgi tendon organs—tendon stretch

C. Nerves
1. Parallel bundles of peripheral axons
a. Enclosed by connective tissue
b. Some may be myelinated
2. Classification based on nature of information
a. Sensory (afferent) nerves
i. Sensory information from periphery to CNS
b. Motor (efferent) nerves
i. Motor information from CNS to periphery
c. Mixed nerves
i. Include sensory and motor

3. Classification based on site of origin
a. Cranial nerves
i. Brain origin
b. Spinal nerves
i. Arise from spinal cord

D. Motor endings
1. Function
a. Activate effectors
i. Release of neurotransmitter
2. Types
a. Neuromuscular junction
i. Contact between motor neuron and muscle
ii. Release ACh
b. Varicosities
i. Contact between autonomic motor endings and visceral effectors and organs,
smooth and cardiac muscle

E. Cranial nerves

I
II
III
IV
V
VI
VII
VIII
IX
X
XI

Cranial Nerve
Olfactory
Optic
Oculomotor
Trochlear
Trigeminal
Abducens
Facial
Vestibulocochlear
Glossopharyngeal
Vagus
Accessory

Sensory Function
YES—smell
YES—vision
NO
NO
YES—general sensation
NO
YES—taste
YES—audition; balance
YES—taste
YES—taste
NO

XII

Hypoglossal

NO

X. Spinal Nerves

Motor Function
NO
NO
YES—eye muscles
YES—eye muscle
YES—chewing
YES—abducts eye
YES—facial expression
NO
YES—tongue and pharynx
YES—pharynx and larynx
YES—head and neck
movement
YES—tongue

A. Nomenclature
1. Named for the level of the vertebral column from which the nerves exits
a. 31 spinal nerves
i. 8 cervical (C 1 – C8)
ii. 12 Thoracic (T 1 – T8)
iii. 5 Lumbar (L 1 – L8)
iv 5 Sacral (S1 – S8)
v. 1 Coccygeal (C 0)
B. Structure (see above)
1. Dorsal and ventral rootlets

2. Dorsal and ventral root
3. Dorsal root ganglion
4. Spinal nerve
5. Dorsal ramus of spinal nerve
6. Ventral ramus of spinal nerve
7. Rami communicantes
a. Autonomic fibers
8. Sympathetic chain ganglion
B. Nerves plexuses
1. Specific to ventral rami
2. Types
a. Cervical
b. Brachial
c. Lumbar
d. Sacral regions
3. Fibers of different ventral rami cross and are redistributed
a. Branches contain fibers originating from different spinal nerves
b. Innervation arrives via multiple routes
i. More than a single spinal nerve serves each limb muscle

C. Dermatomes

1. Area of skin innervated by the cutaneous branch of a single spinal nerve
2. All spinal nerves (except C1) have dermatomes
3. Dermatomes overlap

XI. Reflex Activity
A. Background
1. Stimulus-response sequence
a. Unlearned
b. Unpremeditated
c. Involuntary
2. Mediated by spinal cord circuits
a. Information may ultimately relayed to the brain

B. Components of a reflex arc

1. Receptor
a. Site of stimulus action
2. Sensory neuron
a. Transmits the afferent impulse to the CNS
3. Integration center
a. Monosynaptic reflex
i. Single synapse
b. Polysynaptic
i. Multiple synapses with chains of interneurons
4. Motor neuron
a. Conducts efferent impulse from integration center to effector
5. Effector
a. Muscle fiber or gland
C. Stretch and deep tendon reflexes

1. Muscle spindles

a. Consist of intrafusal fibers
b. Wrapped by afferent sensory endings
i. Type Ia fibers
ii. Type II fibers
c. Gamma () efferent fibers
i. Innervate contractile region of spindle
ii. Maintain spindle sensitivity
2. Extrafusal muscle fibers
a. Skeletal muscle
b. Innervated by alpha () motor neurons
3. Sequence of events
a. Stretching muscle activates muscle spindle
b. Impulse carried by primary sensory fiber to spinal cord
c. Activates alpha motor neuron
i. Sends efferent signal to muscle (effect)

d. Stretched muscle contracts
e. Antagonist muscle is reciprocally inhibited

XII. Overview of the Autonomic Nervous System
A. Somatic Nervous System
1. Voluntary
a. Voluntary muscle movement
2. Sensory information to the CNS
3. Organization of cell bodies
a. Lie within spinal cord or brainstem
b. Targets are controlled monosynaptically
B. Autonomic Nervous System
1. Involuntary
a. Autonomic functions are carried out without conscious, voluntary control
2. Cell bodies of all lower autonomic motor neurons lie outside the CNS
a. Autonomic ganglia
b. Neurons are postganglionic
c. Driven by preganglionic neurons whose cell bodies are in the spinal cord or brainstem
3. Divisions
a. Sympathetic
b. Parasympathetic
4. Divisions differ based on:
a. Neurotransmitter type
b. Fiber length
c. Location of ganglia

d. Function
5. Neurotransmitter
Division
Sympathetic
Parasympathetic

Preganglionic
ACh
ACh

Postganglionic
NE
ACh

a. ACh acts locally
i. ACh always has a stimulatory effect
b. NE has spreads far and can exert its effects over long distances when circulated in the
blood
c. Adrenergic receptors
i. Alpha—stimulatory
ii. Beta—inhibitory (except in the heart when it is excitatory)
6. Fiber length
a. Parasympathetic
i. Long preganglionic
ii. Short postganglionic
b. Sympathetic
i. Short preganglionic
ii. Long postganglionic
7. Location of ganglion
a. Parasympathetic
i. Ganglion is located in visceral organ
b. Sympathetic
i. Ganglia lie close to spinal cord
ii. Sympathetic chain ganglia
8. Function

a. Divisions work in concert
b. Parasympathetic dision
i. Maintenance of function
ii. Energy conservation
c. Sympathetic division
i. Emergence
ii. Intense muscular activity
9. Sympathetic response
a. Pupil dilated
b. Secretory responses inhibited
c. Stimulates sweating
d. Heart function
i. Increases rate
ii. Dilates coronary vessels
e. Increased blood pressure
i. Constricts most vessels
f. Bronchioles dilate
g. Decreased activity of digestive system
h. Piloerection
i. Increase metabolic rate
i. Glucose is released into blood
ii. Lipolysis
j. Increased alertness
h. Causes ejaculation (vaginal reverse peristalsis)
10. Parasympathetic response

a. Pupils constrict
b. Stimulates secretory activity
i. Salivation
c. Heart function
i. Decreases rate
ii. Constricts coronary vessels
d. Constricts bronchioles
e. Increases activity of digestive system
f. Causes erection (penis and clitoris)
i. Vasodilation

XIII. Embryonic Development
A. Background
1. Brain development begins during third gestational week
a. Ectoderm differentiates to form the neural plate
2. Neural plate invaginates to form the neural groove
a. Groove deepens
b. Folds fuse to form the neural tube
i. Occurs by the fourth week of gestation
3. Neural tube differentiates into the CNS
a. Anterior portion forms the brain
b. Posterior portion forms the spinal cord
4. Neural crest is formed when fold cells migrate laterally
a. Neural crest gives rise to sensory neurons and autonomic neurons
5. Anterior develop is rapid

a. Functional divisions are established
i. Primary brain vesicles
6. Types of primary vesicles
a. Prosencephalon
i. Forebrain
b. Mesencephalon
i. Midbrain
c. Rhombencephalon
i. Hindbrain
7. Secondary vesicles form
a. Forebrain is divided
i. Telencephalon
ii. Diencephalon
b. Hindbrain divides
i. Metencephalon
ii. Myelencephalon
B. Brain structures associated with the developmental vesicles
a. Telencephalon
i. Cerebrum
b. Diencephalon
i. Hypothalamus
ii. Thalamus
iii. Epithalamus
c. Mesencephalon
i. Midbrain

d. Metencephalon
i. Pons
ii. Cerebellum
e. Myelencephalon
i. Medulla oblongata

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