Session 2 - The Brachial Plexus

Question 1

What is the structure shown in the image?

Answer 1

The brachial plexus

Question 2

What exactly is the brachial plexus?

Answer 2

A network of nerve fibres that run through the neck and axilla, into the arm.

Question 3

What are the five divisions of the brachial plexus?

Answer 3

Read That Damn Cadaver Book

• Roots
• Trunk
• Divisions
• Cords
• Branches

Question 4

What is A?

Answer 4

Roots of brachial plexus

Question 5

What do 1-5 represent?

Answer 5

The anterior fibres of spinal nerves C5, C6, C7, C8, T1 respectively

Question 6

What is a distinctive feature of the components of A?

Question 7

What is B?

Answer 7

The trunks

Question 8

What is 6, and what is it a combination of?

Answer 8

Superior trunk: A combination of C5 and C6 roots.

Question 9

What is 7?

Answer 9

Middle trunk: A continuation of C7.

Question 10

What is 8?

Answer 10

Inferior trunk: A combination of C8 and T1 roots.

Question 11

When are the trunks formed?

Answer 11

just before they enter the axilla through the axillary inlet (or apex)

Question 12

What is C?

Answer 12

The divisions

Question 13

What are 9 and 10?

Answer 13

9 - Anterior divisons

10 - Posterior divisions

Question 14

What do the divisions leave us with?

Question 15

What is D?

Answer 15

The cords

Question 16

What are the sections of D formed by, and what are they named relative to?

Answer 16

The cords are formed by recombination of the six divisions to three nerve fibres

They are named by their position relative to the brachial artery.

Question 17

What is 11 and what is it formed by?

Answer 17

Lateral cord (lateral to the brachial artery): Formed by…

The anterior division of the superior trunk,
The anterior division of the middle trunk

Question 18

What is 12?

Answer 18

Posterior cord (behind the brachial artery): Formed by….

The posterior division of the superior trunk
The posterior division of the middle trunk
The posterior division of the inferior trunk

Question 19

What is 13?

Answer 19

Medial cord (medial to the brachial artery): Formed by

The anterior division of the inferior trunk.

Question 20

What is 14?

Answer 20

Musculocutaneous Nerve

Question 21

What are the roots of the Musculocutaneous Nerve?

What are its motor functions?

Answer 21

Roots: C5, C6, C7

Motor Functions: Innervates the brachialis, biceps brachii and corocobrachialis muscles

Question 22

What is 15?

What are its roots?

Answer 22

Axillary Nerve

C5 and C6

Question 23

What is the motor function of the axillary nerve?

Answer 23

Innervates the deltoid, teres minor and the long head of the triceps brachii

Question 24

What is 16?

What are its roots?

Answer 24

Median nerve

Roots: C5 – C8 and T1

Question 25

What is the motor function of the median nerve?

Answer 25

Innervates most of the flexor muscles in the forearm

Question 26

What is 17?

What are its roots?

Answer 26

Radial Nerve

Question 27

What is the motor function of the radial nerve?

Question 28

What is 18?

What are its roots?

Answer 28

The ulnar nerve

Roots: C8 and T1

Question 29

What is the motor function of the ulnar nerve?

Answer 29

Innervates the muscles of the hand

Question 30

What can damage to the axillary nerve cause?

Answer 30

Loss of sensation in the regimental patch