Brachial Plexus

Question 1

Define nerve plexus

Answer 1

It is a complex arrangement of the anterior primary rami of certain spinal nerves, allowing mixing of fibres from different segments of the spinal cord and giving branches to supply the muscles and skin of certain parts of the body

Question 2

What is the brachial plexus?

Answer 2

It is a big network of nerves which lies partly in the neck and partly in the axilla and is concerned with the innervation of the skin and muscles of upper limb

Question 3

Types of brachial plexus and their formation

Answer 3

1. Normal type
   Formed of the anterior primary rami of the lower 4 cervical nerves and the first thoracic nerve (C5, C6, C7, C8 and T1)
2. Prefixed type
   Origin of the plexus may shift one segment up
   Receives a large contribution from C4
3. Postfixed type
   Origin may shift one segment down
   Receives large contributions

Question 4

List the stages of the brachial plexus

Answer 4

(Remember To Drink Cold Beer)

1. Roots
2. Trunks
3. Divisions
4. Cords
5. Branches

Question 5

List the roots of the brachial plexus

Answer 5

C5, C6, C7, C8 and T1

Question 6

List the trunks of the brachial plexus

Answer 6

1. Upper trunk - union of C5 and C6
2. Middle trunk - C7
3. Lower trunk - union of C8 and T1

Question 7

How many divisions are there?

Answer 7

6
Each trunk divides into two: Anterior and posterior division

Question 8

List the cords and what forms them

Answer 8

1. Lateral cords - Union of the anterior divisions of the upper and middle trunks; fibres from C5, C6 and C7
2. Posterior cords - Union of the posterior divisions of the 3 trunks; thus, fibres from C5, C6, C7, C8 and T1
3. Medial cords - Anterior division of the lower trunk only; fibres from C8 and T1

Question 9

Number of branches formed by the different cords

Answer 9

1. Lateral cord - 3 branches
2. Posterior cord - 5 branches
3. Medial cord - 5 branches

Question 10

What are the branches given rise to by the roots and the nerves forming them?

Answer 10

1. Nerve to the rhomboids - C5
2. Nerve to Serratus Anterior - C5, C6 and C7

Question 11

What are the branches given rise to by the upper trunk, as well as the nerves forming them?

Answer 11

1. Suprascapular nerve -C5 and C6
2. Nerve to subclavian - C5 and C6

Question 12

Mention the beginning/ starter point of the brachial plexus as well as its termination

Answer 12

It begins in the posterior triangle of the neck at the lateral border of scalenus anterior muscle.
It terminates in the axilla, at the lower border of pectoralis minor muscle, where the cords give their branches which supply the upper limb.

Question 13

Course and relations of:
a. The roots

Answer 13

Lie in upper part of the posterior triangle of the neck between scalenus anterior and scalenus medius muscle

Question 14

Course and relations of:
b. The trunks

Answer 14

Lie in the lower part of posterior triangle of neck

Question 15

Course and relations of:
c. The divisions

Answer 15

Lie behind the middle third of the clavicle

Question 16

Course and relations of:
d.The cords

Answer 16

Lie in the axilla, in relation to axillary artery as follows:

1. relation of cords to the 1st part of the axillary artery
   . medial cord - lies behind the artery
   . lateral and posterior cords - lie lateral to the artery
2. relation of cords to the 2nd part of axillary artery
   . medial cord - lies medial to the artery
   . lateral cord - lies lateral to the artery
   . posterior cord - lies posterior to the artery

Question 17

Course and relations of:
e. Branches

Answer 17

Start at the lower border of pectorals minor muscle and are related to the third part of axillary artery as follows:

i. Branches of medial cord - lie med. to it
1. Medial cutaneous nerve of the arm
2. Medial cutaneous nerve of forearm
3. Medial root of median nerve and ulnar nerve

ii. Branches of the lateral cord - lie lat. to it
1. Musculocutaneous nerve
2. Lateral root of median nerve

iii. Branches of posterior cord - lie post. to it
1. Upper and lower subscapular nerves
2. Nerve to latissimus dorsi
3. Axillary nerve
4. Radial nerve

Question 18

Name the roots of the posterior cord and their nerves

Answer 18

1. Upper subscapular nerve - C5, C6 and C7
2. Nerve to latissimus dorsi - C5, C6, C7 and C8
3. Lower subscapular nerve - C5, C6 and C7
4. Axillary nerve - C5, C6 and C7
5. Radial nerve - C5, C6, C7, C8 and T1

Question 19

List the branches of the medial cord

Answer 19

1. Medial pectoral nerve
   2.Medial cutaneous nerve of the arm
2. Medial cutaneous nerve of forearm
3. Medial root of median nerve and ulnar nerve

Question 20

List the branches of the lateral cord

Answer 20

1. Musculocutaneous nerve
2. Lateral root of median nerve

Question 21

List the branches of the posterior cord

Answer 21

1. Upper subscapular nerve
2. Nerve to latissimus dorsi
3. Lower subscapular nerve
4. Axillary nerve
5. Radial nerve