Lecture 18 Spinal Cord and Spinal Nerves

Question 1

vertebrae

Answer 1

bony structures that surround spinal cord

Question 2

vertebral column

Answer 2

vertebrae stacked on one another

Question 3

vertebral foramen

Answer 3

each individual vertebrae has an opening bounded ventrally/anteriorly by the body of the vertebra

Question 4

vertebral canal

Answer 4

when you stack vertebral foramen holes on top of one another to create a canal where spinal cord is located

Question 5

intervertebral foramina

Answer 5

spaces/openings between the vertebrae where spinal nerves will exit the vertebral canal and extend out to the periphery

Question 6

numbering of nerves (C1, T1…) is based on

Answer 6

which level of the vertebral canal they exit through the foramina

Question 7

why is the spinal cord shorter than the vertebral canal ?

Answer 7

spinal cord stops growing at age 4/5
vertebral column grows till age 18/22

Question 8

how many pairs of spinal nerves are there?

Answer 8

31

Question 9

Roles of spinal cord:

Answer 9

• communication between brain and PNS (below the head)
• provides pathway for nerve impulses
  -sensory info will gather from periphery and enter spinal cord while motor info will go out into muscles from spinal cord

-integrate and produce responses. Determines where sensory info needs to go after its been collected from periphery and can create motor responses

Question 10

spinal cord extends from _ to _

Answer 10

from foramen magnum (hole is base of skull) to L2 (same level as most inferior rib on ribcage)

Question 11

What are the two enlargements on the spinal cord?

Answer 11

1. Cervical - between C4 and T1
2. Lumbosacral - between T9 and T12 vertebrae

associated w/ extra nervous tissue needed to supply additional structures of upper and lower limbs (muscles, bones, tissues that need to be supplied w/ neurons)

Question 12

Corpus Medullaris

Answer 12

tip/end of spinal cord

Question 13

Cauda Equina

Answer 13

hair like nature of nerves coming out of bottom of spinal cord

Question 14

Filum Terminale

Answer 14

extension of the pia mater CT covering around the spinal cord. Anchors spinal cord to inferior part of vertebral column (coccyx). Acts as tether for spinal cord, stops any superior direction movement.

Question 15

where do nerves supplying lower limbs exit? Then they course down through vertebral canal to exit via…

Answer 15

LS enlargement , foramina

Question 16

Meninges in spinal cord?

Answer 16

• dura mater
• arachnoid space
• subdural space
• pia mater
• subarachnoid space

Question 17

Epidural Space is:

Answer 17

space between periosteum (CT on bone) and the dura mater. Space filled w/fat, blood vessels, areolar CT. Helps protect and hold spinal cord in place.
- has pain receptors, epidural during pregnancy blocks these

Question 18

Denticulate Ligaments

Answer 18

pia mater has small extensions of itself that move towards the dura mater

Question 19

Filum Terminale

Answer 19

another extension of pia mater which extends to the coccyx, helps anchor the spinal cord longitudinally and prevents superior/inferior movement

Question 20

what functions do all spinal nerve have?

Answer 20

motor and sensory

Question 21

What columns are in outer white matter of the spinal cord?

Answer 21

two halves, 3 columns in each half
- each column is subdivided into nerve tracts (fasciculi) which allow info to be transmitted in an organised fashion through the spinal cord
- dorsal, ventral, lateral columns

there are ascending and descending tracts of myelinated axons that run the length of the spinal cord

Question 22

What horns are in the inner gray matter of the spinal cord?

Answer 22

posterior - sensory neurons
anterior - motor neurons
lateral - autonomic nervous system

highly organised based on nerve function

Question 23

gray and white commissures

Answer 23

axons that cross from one side of the spinal cord to the other

Question 24

central canal

Answer 24

centre of gray commisure

Question 25

Polio

Answer 25

virus attacks cell bodies of the motor neurons in anterior horn and some of the cranial nerve cell bodies. Results in motor loss and eventually paralysis.

Question 26

ALS

Answer 26

attacks motor neuron cell bodies in brain and spinal cord, eventually ppl loose ability to talk, swallow, breathe. Die within 5 years.

Question 27

pathway of sensory neurons

Answer 27

pass into the posterior horn through dorsal root

synapse with interneurons or enter white matter and ascend or descend the cord

Question 28

pathway of motor neurons

Answer 28

enter anterior horn and exit the ventral root

Question 28

what 3 CT layers surround axons of peripheral nerves

Answer 28

1. endoneurium - separates axons from each other and groups them into bundles called fascicles
2. perineurium - holds fascicles together. Blood supply provided by surrounding arteries and veins
3. epineurium - dense CT layer, continuous w/dura mater of spinal cord

Question 28

cervical plexus

Answer 28

C1-C4 (small)
-innervates superficial neck structures, skin of neck, posterior portion of head, superior portion of shoulder+chest

Phrenic nerve: C3-C5 (cervical and brachial plexuses)
-innervates diaphragm

Question 29

brachial plexus

Answer 29

C5-T1
-3 trunks, 6 divisions
-3 cords, 5 branches