The Spinal Cord and Spinal Nerves

Question 1

Brain consists of

Answer 1

cerebrum, brainstem, and cerebellum

Question 2

CNS vs PNS

Answer 2

CNS = brain and spinal cord
PNS = cranial nerves, spinal nerves, and ganglia

Question 3

Cranial nerves

Answer 3

• arise from brain and brainstem
• special senses: vision, hearing, balance, smell, taste
• general sensation from the face
• voluntary control of striated muscle of the face
• parasympathetic outflow to targets in face (eye glands) as well as thoracic and abdominal viscera

Question 4

Spinal nerves

Answer 4

• general sensation from body and back of head
• voluntary motor control of striated muscle in the body
• all sympathetic outflow (thoracic and abdominoelvic viscera, skin, and targets in the face)
• parasymp outflow to vsiceral organs of pelvis

Question 5

ganglia

Answer 5

sensory and autonomic, associated with both cranial and spinal nerves

Question 6

dermatome

Answer 6

the area of skin innervated by a given spinal level

- every spinal nerve except C1 has a dermatome

Question 7

Myotome

Answer 7

the group of muscles supplies by a given spinal level

Question 8

Lesion of a given spinal nerve results in

Answer 8

stereotyped loss of sensory input and motor output

Question 9

Subarachnoid space

Answer 9

between the arachnoid and pia mater, cerebrospinal fluid

Question 10

Order of meninges

Answer 10

dura mater, arachnoid mater, pia mater

Question 11

Rostrocadual subdivisions of the spinal cord

Answer 11

• 8 cervical spinal nerves (C1 spinal nerve emerges from above the atlas, even though there are only 7 cervical vert.
• 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal

Question 12

Spinal nerves are

Answer 12

bilaterally paired, named according to their associated vertebrae

Question 13

cauda equina

Answer 13

mass of nerves below vertebral level L2

Question 14

conus medullaris

Answer 14

where spinal cord ends at vertebral level L2, more caudal nerves must descend to exit between appropriate vertebrae

Question 15

meninges of the spinal cord

Answer 15

pia covers the cord closely, the dura and arachnoid extend to vertebral level S2 to form the dural sac

Question 16

filum terminale interna

Answer 16

The filum terminale (FT) is a fibrous band that extends from the conus medullaris to the periosteum of the coccyx, and its functions are to fixate, stabilize, and buffer the distal spinal cord from normal and abnormal cephalic and caudal traction.
extends caudally from the conus medullaris

Question 17

lumbar cistern

Answer 17

expanded subarachnoid space between vertebral levels L2 & S2, contains the cauda equina and the filum terminale interna

Question 18

Lumbar puncture

Answer 18

sampling CSF

Question 19

Intervertebral foramina

Answer 19

nerves arise from the spinal cord and extend toward the intervertebral foramina, exit between adjacent vertebra

Question 20

What fills the epidural space

Answer 20

fat and BVs, this is the site of an epidural anaesthetic injection

Question 21

what holds the arachnoid against the dura

Answer 21

hydrostatic pressure of CSF

Question 22

Spinal nerves are formed by the union of a

Answer 22

dorsal and ventral root, so contain both sensory and motor fibres (are MIXED nerves)
- lesion of a spinal nerve may result in both sensory and motor sign

Question 23

White matter in the spinal cord

Answer 23

• sulci delineate the white matter into columns
• carries sensory info upward and motor info downward
• three columns/funiculi; dorsal funiculus (column), lateral funiculus, ventral funiculus
• amount decreases as you go down caudally

Question 24

Grey matter in the spinal cord

Answer 24

• deep, forms a continuous column extending length of the cord
• at all levels, there are dorsal horns (primarily sensory neurons) and ventral horns (primarily motor neurons)
• at some levels there are intermediolateral cell columns present

Question 25

Ventral horns are enlarged at which levels

Answer 25

cervical and lumbar

Question 26

cervical enlargement

Answer 26

ventral horns from C5 - T1 contain somatic motor nerves innervating the arms

Question 27

Lumbosacral enlargement

Answer 27

ventral horns from L2-S2 contain somatic motor nerves innervating the legs

Question 28

intermediolateral (IML) cell columns form...

Answer 28

- lateral horns from T1 to L2 | - they also exist from S2-S4 but because of large ventral horns, they do not form a distinct lateral horn

Question 29

IML cell columns contain

Answer 29

- cell bodies of sympathetic preganglionic neurons from T1 to L2 - cell bodies of parasympathetic preganglionic neurons from S2-S4 (axons form the pelvic splanchnic nerves)

Question 30

Dorsal roots

Answer 30

- carry sensory information (from body wall, limbs, viscera), so dorsal horns are also sensory - lesion of a dorsal root - sensory signs seen in a dermatomal distribution

Question 31

Dorsal root ganglia

Answer 31

contain cell bodies of sensory neurons

Question 32

Ventral roots

Answer 32

- carry motor information (somatic and visceral) - somatic motor neurons come form the ventral horn and control striated muscle of the body wall, while visceral motor neurons come from the IML cell columns and control visceral targets - lesion of a ventral root will manifest with motor signs in a myotomal distribution

Question 33

herniated disc

Answer 33

compressed section of spinal nerve resulting in various deficits depending on the level - nucleus pulposus is centre core of an intervertebral disc and it oozes out compressing the nerve

Question 34

nerve plexus

Answer 34

plexus meaning braid Overlapping network between ventral rami and final compound peripheral nerve - dorsal and ventral rami (where they split) of spinal nerves are mixed nerves. Sometimes ventral rami of some spinal nerves blend to create compound nerves carrying axons from 2 or more spinal segments (multiple spinal levels)

Question 35

What does it mean if a muscle is innervated by a compound nerve?

Answer 35

means it is controlled by more than one spinal segment

Question 36

True or False: viscera only receive parasympathetic output

Answer 36

false they are controlled by both symp and parasymp. | - outflow from both systems originate from different regions of CNS but they overlap to form a visceral plexus

Question 37

reflex

Answer 37

involuntary motor response - input can be external or internal stimuli - motor response can involve skeletal, cardiac, or smooth muscle (somatic or visceral system)

Question 38

reflex arc

Answer 38

from receptor to effector somatic reflex ex. patellar reflex (monosynaptic) visceral reflex ex. urinary bladder stretches