Spinal Cord and Somatic Nervous System

Question 1

what are all named nerves classified as?

Answer 1

peripheral nerves

Question 2

what are sensory nerves?

Answer 2

AFFERENT –> towards CNS

Question 3

what are motor nerves?

Answer 3

EFFERENT –> away from CNS

Question 4

describe cranial nerves

Answer 4

-12 pair
-brain, brainstem
-pass through foramina in skull

Question 5

describe spinal nerves

Answer 5

-exact number varies from species to species
-from spinal cord
-pass through intervertebral foramina

Question 6

describe the somatic nervous system (motor and sensory)

Answer 6

-innervates the body wall (parietal structures)
-provides voluntary motor control over skeletal mm
-includes most of the cranial nerves and the spinal nerve

Question 7

what is each spinal nerve complex responsible for?

Answer 7

one dermatome = body segment

Question 8

describe the spinal nerve complex

Answer 8

includes both the somatic nervous system and part of the ANS

Question 9

what is grey matter?

Answer 9

cell bodies

Question 10

what is white matter and why is it white?

Answer 10

axons
b/c its myelinated

Question 11

what is the grey matter subdivided into?

Answer 11

dorsal and ventral horn (each leads to dorsal and ventral root)

Question 12

where are somatic cell bodies and somatic motor axons found respectively?

Answer 12

cell bodies –> ventral horn
motor axons –> ventral root

Question 13

where are sensory cell bodies and sensory axons found respectively?

Answer 13

cell bodies –> dorsal root ganglion
axons –> dorsal root

Question 14

what is the mixed spinal nerve and where is it found?

Answer 14

mixture of dorsal and ventral roots

found distal to the dorsal root ganglion

Question 15

where do dorsal rami go?

Answer 15

epaxial musculature

Question 16

where do ventral rami go?

Answer 16

hypaxial musculature

Question 17

what is CNS gray matter?

Answer 17

-cell bodies of neurons and glia
-proximal dendrites, glial processes
-neuropil

Question 18

what are neuropils

Answer 18

dense meshwork of fibers and glial cell processes
no CT integrated into CNS

Question 19

what is CNS white matter?

Answer 19

-axons mostly myelinated
-glial cells

Question 20

what is the conus medullaris?

Answer 20

the end of the spinal cord –> varies across mammals

vertebral column grows faster than spinal cord

SPINAL CORD ALMOST ALWAYS STOPS BEFORE THE VERTEBRAL CANAL

Question 21

what is the cauda equina?

Answer 21

the extension of dorsal and ventral roots to the same numbered vertebral level

Question 22

describe how nerves come out from vertebrae

Answer 22

C1-C7: cranial area/comes out above

extra C8 so T1-T2 nerves come out CAUDAL

Question 23

what are the meninges?

Answer 23

-coverings of the spinal cord

-CTs
-support, protect
-dura mater, arachnoid mater, pia mater

Question 24

what is the dura mater?

Answer 24

–> means tough mother
-external meningeal layer
-continuous with the true dura of the brain
-surrounded by extradural fat in the epidural space
-extends laterally onto proximal spinal nerves

=dural sheath
anchored to the caudal vertebrae via the filum terminale

Question 25

what is the arachnoid mater?

Answer 25

=spider mother
-just deep to the dura and adherent to it
-thin and delicate
-encloses the subarachnoid space, filled with CSF
-continuous with the subarachnoid space around the brain

Question 26

what is the pia mater?

Answer 26

=tender mother
-innermost meningeal layer
-completely adherent to the spinal cord

-create denticulate ligaments
-creates filum terminal internus