Chapter 7: Spinal CordAnatomy & PhysiologyKasprowicz

Quick Review• Gray matter vs. white matter - location - composition

Terminology:CNS neurons - nuclei; tractsPNS neurons - ganglia; nerves

Location & Appearance• cylindrical; ~ 17 inches (42 cm)

long• Glistening white appearance• Protected by the vertebrae & the

meninges• ~ size of thumb in diameter;

enlargements in the cervical and lumbar regions (near limbs)

Location & Appearance• Continuous with the medulla

oblongata; extends to the first or second lumbar vertebrae

(just below the ribs)• Ends in a collection of spinal

nerves called the cauda equina

General Functions• 2 way impulse conduction

pathway to and from the brain from the body

• Major reflex center

Video Preview of Spinal Cord

Spinal Cord Anatomy· Internal gray matter (mostly cell

bodies); resembles a butterfly or the letter H

· Surrounds the central canal containing cerebrospinal fluid

Spinal Cord Anatomy·Dorsal (posterior) horns – contain interneurons and cell bodies of sensory neurons· If damaged, sensation from the body will be lost

·Anterior (ventral) horns – contain cell bodies of motor neurons

Spinal Cord Anatomy· Exterior white matter

conduction tracts·Sensory tracts – (afferent); tracts conducting sensory impulses to the brain·Motor tracts – (efferent); carry impulses from the brain to skeletal muscles· one side to the other

Chapter 7: Peripheral Nervous System

Anatomy & PhysiologyKasprowicz

Peripheral Nervous System• Contains nerves (bundles of

neuron axons) & ganglia (groups of neuron cell bodies) found outside the CNS

• Includes both sensory (afferent) and motor (efferent) nerves

Structure of a Nerve in the PNS• Similar “packaging” to a muscle

fiber

• Neuron fibers (axons) are bundled by connective tissue

Structure of a Nerve in the PNS

Structure of a Nerve in the PNS• Individual nerve cell process is

covered by the endoneurium.• Groups of nerve cell processes

are bundled together into a fascicle, surrounded by the perineurium.

• Fascicles are bound together by the epineurium = NERVE

Cranial Nerves• 12 pairs that innervate the head and neck; the vagus nerves travel to the thoracic and abdominal cavities

Cranial Nerves: Function

I. Olfactory (bulb & tract) sensory; sense of smell

II. Optic sensory; sense of sight

(vision)

Cranial Nerves: FunctionIII. Oculomotor midbrain eye; motor

control of the eyeball, eyelid, lens shape & pupil size

IV. Trochlear midbrain eye; motor

control of eye muscle

Cranial Nerves: FunctionV. Trigeminal pons face - sensory impulses from

skin on face; inside nose & mouth

- activate chewing (motor)

Cranial Nerves: FunctionVI. Abducens pons eye; motor control

of eye muscle

Cranial Nerves: FunctionVII. Facial pons face; - motor control of facial

muscles, lacrimal & salivary glands

- sensory impulses from taste buds

Cranial Nerves: FunctionVIII. Vestibulocochlear inner ear brainstem; sensory information - vestibular (balance) - cochlear (hearing)

Cranial Nerves: FunctionIX. Glossopharyngeal medulla throat; - motor control of swallowing - sensory input from taste

buds & pressure receptors in carotid artery

Cranial Nerves: FunctionX. Vagus medulla thorax & abdomen sensory/motor impulses from &

to throat, voicebox, viscera of chest & abdominal cavities

(parasympathetic motor neurons)

Cranial Nerves: FunctionXI. Accessory medulla & superior spinal cord

muscles of neck/back motor control of sternocleidomastoid & trapezius muscles

Cranial Nerves: FunctionXII. Hypoglossal medulla tongue sensory & motor impulses

from/to the tongue

Mnemonic Device

•Oh, oh, oh, to touch and feel very good velvet, ahhh.

PNS: Spinal Nerves & Nerve Plexuses

Anatomy & PhysiologyKasprowicz

Spinal Nerves • 31 pairs consisting of the

ventral & dorsal roots of the spinal cord

• ½ long• Divide into the dorsal rami &

ventral rami

Spinal Nerves

Spinal Nerves • Dorsal rami skin/muscles of

posterior body trunk• Ventral rami - T1-T12 (rib muscles, skin/muscles of anterior & lateral trunk) - form plexuses

Plexuses• Complex networks of nerves

serving the sensory & motor needs of the limbs

1) cervical plexus diaphragm, shoulder & neck

Plexuses 2) brachial plexus shoulder, upper thorax, arm & hand 3) lumbar plexus lower abdomen, hip & thigh 4) sacral plexus lower trunk, glutes, leg & foot

Lumbar

Plexus

Sacral Plexus

1

2

3

4

5

6

7

8

9

10

1112

13

A

B

CD

E

F

A

B

C

D

E

F

G

H

I

J

front

back

L1

L2

L3D3

D2

D1

B3

B2

B1

C1

A

B C D

E

F