Spinal nerves & plexuses

Question 1

How many spinal nerves are there?

Answer 1

31 pairs

Question 2

How are the spinal nerves named?

Answer 2

For the vertebrae at the level of the spinal cord where they originate

Question 3

List the number of spinal nerves in each area of the spinal cord

Answer 3

8 cervical
12 thoracic
5 lumbar
5 sacral
1coccygeal

Question 4

where do the spinal nerves emerge?

Answer 4

Through the intervertebral foramina; for the sacral nerves, through the 5 sacral foramina

Question 5

Where does the first cervical nerve emerge?

Answer 5

Between C1 and the occipital bone

Question 6

Where does the 8th cervical nerve emerge?

Answer 6

Between C7 and T1

Question 7

Where do the lumbar and thoracic nerves and C2-C7 nerves emerge?

Answer 7

Between the vertebra sharing its designation with the nerve and the next (inferior) vertebra

Question 8

What is a nerve plexus?

Answer 8

A rearrangement of spinal nerve axons to serve specific body areas/functions

Question 9

how many spinal nerve plexuses are there?

Answer 9

4

Question 10

This plexus is served by nerves C1-C5 and innervates the posterior head and neck

Answer 10

Cervical plexus

Question 11

This nerve connects to the diaphragm and is in the cervical plexus

Answer 11

Phrenic nerve

Question 12

This plexus is served by C4-T1 and innervates the upper limbs

Answer 12

Brachial plexus

Question 13

This nerve is the large nerve of the brachial plexus that branches into the axillary nerve (armpit)

Answer 13

Radial nerve

Question 14

Name the nerves that travel down the arm

Answer 14

Radial nerve, ulnar nerve, median nerve

Question 15

This plexus is served by the ventral rami of T12-L4 and innervated the pelvic region and anterior leg

Answer 15

Lumbar plexus

Question 16

This is the major nerve of the lumbar plexus that branches into the saphenous nerve of the anterior lower leg

Answer 16

Femoral nerve

Question 17

This plexus is served by L4-5 and S1-S4 and innervates the posterior leg and foot

Answer 17

Sacral plexus

Question 18

This is the large nerve of the sacral plexus that travels across the hip and down the leg

Answer 18

Sciatic nerve

Question 19

These are the nerves that combine into the sciatic nerve

Answer 19

tibial nerve, fibular nerve

Question 20

This plexus is formed by the thoracic nerves

Answer 20

Thoracic nerves are NOT part of a plexus–they emerge to create the intercostal nerves

Question 21

How do plexuses form?

Answer 21

By fusion of ventral rami during development

Question 22

What is the purpose of plexuses?

Answer 22

Redundant innervation of the limbs

Question 23

What is the dermatome?

Answer 23

Map of innervated sensory regions

Question 24

Describe the cervical plexus

Answer 24

Ventral rami of C1-C5
Neck, thoracic cavity, diaphragm
Major nerve: phrenic (controls diaphragm)

Question 25

Describe the brachial plexus

Answer 25

Ventral rami of C5-T1
Pectoral girdle & arms
Major nerves: musculocutaneous, axillary, median, radial, ulnar

Question 26

Describe the lumbar plexus

Answer 26

Ventral rami of T12-L4
Pelvic girdle & leg (upper & anterior)
Major nerves: femoral, obturator

Question 27

Describe the sacral plexus

Answer 27

Ventral rami of L4-S4
pelvic girdle & leg (hammies, lower leg)
Major nerves: Sciatic, tibial, common, fibular