Anatomy: Nervous System

Question 1

CNS

Answer 1

Inside skull and vertebral column

Brain, spinal cord

Question 2

spinal nerves and differential

Answer 2

31 pair

8 cervical

12 thoracic

5 lumbar

5 sacral

Question 3

a collection of nerve cell bodies (or in some cases, a single nerve cell body) associated with peripheral nerves and located outside the CNS

Answer 3

Ganglia

Question 4

Sensory ganglia are ______ polar

Answer 4

DRG — pseudounipolar

Cranial ganglia - some bipolar

Question 5

Autonomic, motor or visceral ganglia are _____polar

Answer 5

mutlipolar

Question 6

Gray matter

Answer 6

contains the Nerve Cell Bodies and Synapses (unmyelinated)

Question 7

White Matter

Answer 7

consists of Axons which form Tracts (myelinated)

Question 8

Variations in Spinal Cord

Answer 8

1. Cord gets smaller caudally
2. Progressive decrease in white matter at lower levels: number of nerve fibers decreases caudally as descending tracts gradually terminate and ascending tracts aren’t yet complete.
3. Shape of cord: cervical segments are large and oval, while lumbar and sacral segments are smaller and rounder.
4. Gray matter larger at cervical (C4-T1) and lumbosacral (L2-S3) levels: due to larger number of nerve cells associated with innervation of the limbs.
5. Lateral horn present in T1-L2/L3 segmental levels (aka intermediolateral cell column): contains the cell bodies of preganglionic sympathetic neurons.
6. Dorsal or posterior column (funiculus) divided into two fasciculi (f. gracilis and f. cuneatus) above T6.

Question 9

Lateral horn contains

Answer 9

contains the cell bodies of preganglionic sympathetic neurons.

Only T1-L2

Question 10

Dorsal or posterior horn

Answer 10

a. Sensory horn – involved in the relay of sensory information
b. Contains multipolar neurons that send their axons to:
i. higher levels in the CNS (upper spinal cord, brain stem or diencephalon
ii. ventral or anterior horn cells (these are interneurons)

Question 11

Ventral Horn contains

Answer 11

Motor horn

i. alpha motor neurons (multipolar neurons) that send their axons to innervate extrafusal skeletal muscle fibers/cells. These alpha motor neurons are known also as lower motor neurons
ii. gamma motor neurons (multipolar neurons) that innervate the intrafusal muscle fibers/cells of the neuromuscular spindle

Question 12

Dorsal column contains

Answer 12

mainly ascending nerve cell processes whose cell bodies are located in dorsal root ganglia.

Carries the sensory modalities of discriminative touch and proprioception (position sense).

Question 13

Lateral column

Answer 13

a. Contains ascending sensory nerve fibers (tracts) and descending motor nerve fibers (tracts)
b. Sensory nerve fibers (tracts) have their cells of origin in the gray matter of the dorsal horn, while motor nerve tracts have their cells of origin in upper levels of the neuraxis (brain stem or cerebrum).

Question 14

Ventral/anterior column

Answer 14

a. Contains ascending sensory nerve fibers (tracts) and descending motor nerve fibers (tracts)
b. Sensory nerve fibers (tracts) have their cells of origin in the gray matter of the dorsal horn, while motor nerve tracts have their cells of origin in upper levels of the neuraxis (brain stem or cerebrum).

Question 15

i_mplies a relation to the body wall and the limbs_

Answer 15

somatic

Question 16

Somatic nerves found in both ___ and ____ nerves

Answer 16

cranial and spinal nerves

Question 17

Somatic sensory fibers

Answer 17

a. Sensory nerves to and from skin, skeletal muscle and joints
b. Nerve cell bodies located in cranial and spinal sensory ganglia

Question 18

Somatic Motor Fibers

Answer 18

a. Responsible largely for voluntary control of skeletal muscle
b. Motor nerve cell bodies located in central nervous system (brain stem and spinal cord) - one efferent (motor) neuron (axon) for each cell body

Question 19

implies a relation to the organs of the body cavities, and is extended in this case to include blood vessels and glands that lie outside the body cavities

Answer 19

Visceral

Question 20

Visceral nerve fibers found in both ____ and ______ nerves

Answer 20

cranial and spinal nerves

Question 21

Visceral sensory fibers

Answer 21

a. Sensory nerves from the viscera (heart, lungs, GI tract, urinary system, blood vessels, etc
b. Nerve cell bodies of these afferents are located in the cranial** and **spinal sensory ganglia

Question 22

Visceral motor fibers responsible for involuntary regulation of____

Answer 22

smooth muscle, cardiac muscle and glands

Question 23

ANS is a ____ neuron system

Answer 23

2

(1) The first located in the CNS
(2) The second located in an autonomic (visceral) ganglion

Question 24

Major divisions of ANS

Answer 24

(1) Sympathetic nervous system
(2) Parasympathetic nervous system
(3) Enteric nervous system – neurons (nerve cell bodies and processes) located in the gastrointestinal tract

Question 25

Dorsal root =

Answer 25

sensory root

Sensory or afferent nerve fibers

DRG or spinal ganglion on each DR

(1) Contains all peripheral sensory nerve cell bodies (somatic and visceral)
(2) Pseudounipolar neurons – found only in sensory ganglia (DRG and cranial nerve sensory ganglia)
(3) Central and adjacent peripheral processes of these nerve cells make up the dorsal root. The central process extends into the spinal cord, while the peripheral process forms the spinal nerve.

Question 26

Ventral Root

Answer 26

a. Motor or efferent nerve fibers relative to the spinal cord
b. The cell bodies that send their axons through the ventral roots are located in the ventral and lateral horns (gray matter) of the spinal cord. The ventral root joins the dorsal root to form the spinal nerve.

Question 27

Spinal nerves formed by

Answer 27

union of a dorsal root and a ventral root peripheral to the intervertebral foramina for each segment.

The spinal nerve contains all the motor and sensory axons leaving and entering a given spinal cord segment.

Typically, very short, i.e., about 1/4-inch.

Question 28

Supplies muscular and cutaneous branches to the deep muscles and skin of the back and posterior head.

Answer 28

Dorsal (posterior) primary ramus

Question 29

Supplies muscular and cutaneous branches to the skin and skeletal muscles of the lateral and anterior aspects of the trunk, and the skin and muscles of the limbs.

Answer 29

Ventral (anterior) primary rami

Question 30

Cranial nerves (vs spinal nerves)

Answer 30

1. Each cranial nerve may be purely sensory, purely motor, or mixed (motor/sensory).
2. Cranial nerves do NOT have dorsal and ventral roots or dorsal and ventral rami.

Question 31

There are ____ sympathetic ganglia associated w/ cranial nerves

Answer 31

none

only sensory and parasympathetic ganglia

Question 32

Nucleus

Answer 32

collection of cell bodies in CNS

gray matter