Spinal nerve roots/rootlets

Question 1

Ventral nerve roots

Answer 1

Series of only motor roots in the GVE and GSE respsctive to each spinal cord segment that go to the periphery

Question 2

What is a nerve root a composite of?

Answer 2

Rootlet

Question 3

What protion of the spinal cord do ventral nerve rootlets form off of?

Answer 3

Ventral lateral sulcus

Question 4

Dorsal nerve roots

Answer 4

• Series of only sensory roots (respective to each spinal cord segment) that collects to form the sensory axons to the spinal cord
• collection of central axonal processes from the pseudounipolar neurons in the dorsal root ganglions (directly medial to the root)

Question 5

Dorsal root ganglion

Answer 5

• Aka the spinal ganglion/ posterior root ganglion
• the “bump” directly medial to the dorsal nerve root
• where all spinal nerve sensory nerve bodies are found

Question 6

Central Axon Processes

Answer 6

One branch of the pseudounipolar neurons found in the spinal ganglion (the other is peripheral)

Question 7

Where do dorsal rootlets enter the spinal cord?

Answer 7

Dorsal lateral sulcus

Question 8

Spinal nerve

Answer 8

• formed near the intervertebral foramen/ distal to spinal ganglion
• ventral/dorsal nerve roots join to form this (same vertebral level)
• has both motor and sensory fibers

Question 9

of nerve pairs per a division of the spinal cord

Answer 9

8 cervical – 12 thoracic – 5 lumbar – 5 sacral – 1 coccygeal

Question 10

How are cervical spinal nerves named?

Answer 10

What vertebrae they pass superior to

Question 11

How are thoracic and lumbar nerves named?

Answer 11

By what vertebrae they pass inferior to

Question 12

How do the spinal nerves change the more inferior they exit along the spinal cord?

Answer 12

Lower spinal nerves are much longer and have to travel inferiorly before traveling obliquely so they exit at the correct vertebral level

Question 13

Sacral spinal nerves

Answer 13

• Are found in the sacral canal (S1-S4)
• Each must branch into ventral and dorsal rami before exiting via the ventral/dorsal sacral foramina

Question 14

Which nerves exit via the sacral hiatus?

Answer 14

S5 and Co1 (coccygeal)

Question 15

Cauda equina

Answer 15

Dorsal/ventral roots of L2 to Co that emerge from the conus medullaris

Question 16

Dorsal/Ventral Rami

Answer 16

• Lateral division of the spinal nerve that extends to/from the target nerve ending
• Each contains both afferent and efferent fibers

Question 17

Dorsal Rami

Answer 17

Innervate skin, muscles, joints, of vertebral column/nearby structures

Question 18

Ventral rami

Answer 18

• Innervate all structures anterior to the vertebral column including: limb structures/embryological derivates
• Much larger than dorsal rami

Question 19

Dermatome

Answer 19

• Area of skin innervate by a single spinal cord segment
• Sensory cell bodies are in dorsal root ganglia

Question 20

Torso dermatome pattern

Answer 20

Banded with some overlap

Question 21

High yield dermatomes

Answer 21

T4 – Nipples; T10 – umbilicus; C6 –pad of thumb;

C8 – pinky; S5 – anus

Question 22

Dermatomes and herpers zoster

Answer 22

Shingles presents as a stripped pattern on the torso because virus lives in the nerve cell bodies with the spinal ganglia

Question 23

Limb dermatome pattern

Answer 23

Does not match the peripheral nerve due to plexuses

Question 24

General segmental muscle innervation rule

Answer 24

Most muscles are innervated via 2 or more spinal nerves and 1 spinal nerve may help to supply many muscles