Spinal nervous system

Question 1

what are the two types of peripheral nerves?

Answer 1

cranial nerves and spinal nerves

Question 2

where are the gray and white matter in the cross section of a spinal cord

Answer 2

gray- butterfly in the middle. white- outside

Question 3

what is white matter?

Answer 3

primarily axons organized into tracts

Question 4

what is gray matter?

Answer 4

neuronal cell bodies

Question 5

what is the significance of the intervetebral foramina

Answer 5

holes created by the inferior and superior processes of adjacent vertebrae where nerves leave the spinal column

Question 6

where does the spinal column end? what is this called?

Answer 6

ends ~L1 L2 at the conus medullaris

Question 7

what is the cervical enlargement? the lumbar enlargement? where are they?

Answer 7

reflect a larger number of neuronal cell bodies. C5-T1 (upper extremeties) and L1-S3 (lower extremeties)

Question 8

describe the meninges

Answer 8

dura mater is the outermost layer and the toughest- forms a tube called the dural sac. the epidural space is between the dura and the vertebral canal. the subdural space is next, which is empty. the arachnoid mater is closely associated with the dura matter and lines the dural sac ( not connected). the subarachnoid space is filled with CSF. the pia mater is closely associated with (not separable) the spinal cord.

Question 9

describe the conus medullaris

Answer 9

the end of the spinal cord. as the spinal cord/pia mater thins, it becomes the internal filum terminale (internal because it is still within arachnoid mater and dural sac. It eventually leaves the archnoid mater and dural sac and becomes the external filum terminale (still has dura mater)

Question 10

what are denticulate ligaments

Answer 10

connective tissue that connects pia mater to the dura

Question 11

how many total peripheral nerves are there (spinal + cranial)

Answer 11

12 cranial + 8 cranial + 12 thoracic + 5 lumbar + 5 cranial + 1 coccygeal

Question 12

difference between ventral and dorsal roots?

Answer 12

ventral- motor, dorsal- sensory and w/ ganglia

Question 13

dorsal root ganglion

Answer 13

in the dorsal root of the spinal cord- contains neuronal cell bodies

Question 14

dorsal and ventral rami

Answer 14

after the dorsal and ventral roots meet at the spinal nerve, they separate again into the dorsal and ventral rami. dorsal innervates the back while ventral travels around the body wall and innervates the neck trunk and limbs. note that both rami carry motor and sensory signals

Question 15

difference between typical and atypical spinal nerves?

Answer 15

typical ventral rami are thoracic (T2-12) and their nerves get carried around the body wall with ribs (don’t form plexuses). atypical rami (cervical, lumbar, saccral, T1) form plexuses

Question 16

describe how spinal nerves leave the spinal column

Answer 16

nerves 1-7 leave the spinal cord on top of their corresponding vertebrae. The 8th cervical nerve leaves below the 7th vertebrae, and thus all other nerves are named after the vertebrae they are below.

Question 17

what are cauda equina?

Answer 17

“horses tail”. The nerves at the bottom of the spinal cord must travel farther to reach their appropriate intervertebral foramina and are known as the cauda equina.

Question 18

define nerve

Answer 18

bundle of many neuron fibers

Question 19

describe the differences between tracts, ganglia, nucleus and nerves

Answer 19

in CNS, groups of cell bodies are nuclei and a collection of axons is a tract. In the PNS, groups of cell bodies are a ganglia and collections of axons are called nerves

Question 20

describe some ways that nerves can be classified besides sensory/motor

Answer 20

efferent- away from CNS, afferent- towards CNS. somatic- innervating muscle/skin/skeleton visceral- innervating visceral organs

Question 21

describe what types of neurons you find where

Answer 21

pseudobipolar- afferent; multipolar- efferent; two neuron chain (still multipolar)- two neuron chain