Organization of the Somatic Nervous System

Question 1

Central Nervous System (CNS)

Answer 1

brain and spinal cord

Question 2

peripheral nervous system (PNS)

Answer 2

cranial and spinal nerves plus autonomic nerves in the gut

spinal nerves, cranial nerves, and all autonomic nerves

Question 3

gray matter or nuclei

Answer 3

cell bodies in the CNS

Question 4

white matter

Answer 4

cell processs (axons and dendrites) in the CNS; consists of fiber tracts

Question 5

ganglia

Answer 5

cell body locations outside of the CNS (in the peripheral nervous system)

Question 6

nerves

Answer 6

cell processes (axons and endrites) outside of the CNS (in the PNS)

Question 7

somatic nerves

Answer 7

spinal nerves in the body wall, pass between vertebrae and are named accordingly

8 pairs of cervical nerves, 12 pairs of thoracic, 5 pairs of lumbar, 5 pair of sacral, 1-3 pairs of coccygeal nerves

ventral rami in the cervical, lumbar, and sacral regions interconnect to form a plexus in each region

Question 8

autonomic nerves

Answer 8

primarily innervate visceral structures related to gut

Question 9

afferent neurons

Answer 9

sensory neurons carrying impulses toward the central nervous system

pseudounipolar, cell bodies in dorsal root ganglia

unusial in that the “dendrite” is myelinated

Question 10

efferent neurons

Answer 10

motor neurons carrying impulses away form the CNS

multipolar, found in spinal nerves, cell bodies in ventral horn of spinal chord

Question 11

pseudounipolar

Answer 11

one process divides into a very long dendrite and a relatively short axon

Question 12

multipolar

Answer 12

many dendrites and an axon

Question 13

plexus

Answer 13

the interconnection of ventral rami in the cervical, lumbar, and sacral regions

Question 14

intercostal nerves

Answer 14

the ventral rami of thoracic spinal nerves

Question 15

dorsal horn

Answer 15

contains the cell bodies of the sensory neurons

does NOT include cell bodies for general and visceral sensory neurons in spinal nerves

Question 16

ventral horn

Answer 16

contains the cell bodies of the motor neurons

Question 17

What does the neural plate give rise to?

Answer 17

the nervous system, induced by the notochord

Question 18

What does the neural tube give rise to?

Answer 18

the central nervous system plus somatomotor and presynaptic autonomic neurons - all peripheral neurons whose cell bodies are in the CNS

Question 19

What does the neural crest give rise to?

Answer 19

neurons whose cell bodies are outside the central nervous system (all ganglia and peripheral sensory neurons) and also melanocytes

Question 20

spina bifida

Answer 20

normal spinal cord and meninges, but with vertebral arch defect

several different severities including spina bifida occulta and CSF cysts

Question 21

rachischisis

Answer 21

malformed spinal cord exposed on the surface

Question 22

meningocele

Answer 22

normal spinal cord with defective dura and aracnhoid herniation

Question 23

myelomeningocele

Answer 23

normal spinal cord with defective dura and arachnoid herniation

in addition there is a displaced spinal cord

Question 24

dorsal and ventral rami

Answer 24

travel through and supply hte DEEP BODY WALL consisting bone, muscle, deep fascia, and parietal plerua and peritoneum

consists of general sensory neurons, somatomotor neurons, and postsynaptic sympathetic neurons

Question 25

cutaneous branches

Answer 25

leave the deep body wall to supply the SUPERFICIAL BODY WALL consisting of skin, superficial fascia, and Scarpa’s fascia

no skeletal muscle, so there are only general sensory neurons and postsynaptic sympathetic neurons

Question 26

What are the three cutaneous branches of every spinal nerve?

Answer 26

posterior, lateral, and anterior cutaneous branches

Question 27

meninges

Answer 27

refer to the three coverings of the spinal cord within the vertebral canal

includes the dura mater, arachnoid, and pia mater

Question 28

dura mater

Answer 28

tough outer layer, creats a sheath that covers the nerves as they leave the main spinal column, wraps the dorsal and ventral roots together

Question 29

arachnoid

Answer 29

the thin, spider web-like middle layer which sends projections to the pia mater

Question 30

pia mater

Answer 30

tightly adheres to the surface of the spinal cord and brain

Question 31

epidural space

Answer 31

contains fat and the internal vertebral plexus of veins

Question 32

internal vertebral plexus

Answer 32

important because blood is shunted into this plexus from the superior and/or inferior vena cava with increased pressure in the thorax or abdomen to facilitate venous return to the herat

priminent route for metastases from the prostate gland to the brain

Question 33

subarachnoid space

Answer 33

space between the pia mater and the arachnoid

containts cerebrospinal fluid, no space between arachnoid and dura in life because the CSF presses against the dura

Question 34

conus medularis

Answer 34

the tapering end of the spinal cord atht the L1 vertebral level

Question 35

denticulate ligaments

Answer 35

“tooth-like” pia mater extensions which anchor the cord to the vertebral column

Question 36

filum terminale

Answer 36

inferior pia mater extension from the cord to the coccyx which anchors the cord inferiorly

Question 37

cauda equina

Answer 37

dorsal and ventral roots below the end of the cord coursing toward the appropriate level of exit from the vertebral column

Question 38

locations of needle placement for anesthesia to “block” spinal nerve roots

Answer 38

epidural and subarachnoid

Question 39

lumbar puncture/tap

Answer 39

a needle placed in the subarachnoid space below the level of L1 will have little risk in puncturing/damaging the spinal cord

all of the cauda equine nerve roots will be anesthetized