The Brachial Plexus

Question 1

What is the brachial plexus and what are its roots

Answer 1

It is a network of nerve fibres supplying skin and musculature of upper limb

Roots are formed by anterior rami of C5-T1

Question 2

What can the brachial plexus be split up into (the names of the parts, in the correct order)

Answer 2

Roots

Trunks

Divisions

Cords

Branches

Question 3

What are the trunks of the brachial plexus and what roots form them

Answer 3

Superior trunk - C5 and C6 roots

Middle trunk - C7 root

Inferior trunk - C8 and T1 roots

Question 4

What are the divisions of the brachial plexus

Answer 4

Trunks split into anterior and posterior divisions - so two divisions per trunk (anterior and posterior)

Question 5

What are the cords of the brachial plexus, and which divisions form them

Answer 5

Named by position relative to axillary artery

Lateral cord - anterior division of superior, anterior division of middle

Posterior cord - posterior division of superior, posterior division of middle, posterior division of inferior

Medial cord - anterior division of inferior

Question 6

What are the branches of the brachial plexus and which Roots form them (and which cords)

Answer 6

Musculocutaneous nerve - C5, C6, C7 - lateral cord

Axiallry nerve - C5 and C6 -posterior cord

Median nerve - C6-T1 - lateral and medial cord

Radial nerve - C5-T1 - posterior cord

Ulnar nerve - C8 and T1 - medial cord

Long thoracic nerve - C5-C7 - from anterior rami of spinal nerves

Medial pectoral nerve - C8-T1 - medial cord

Lateral pectoral nerve - C5-C7 - lateral cord

Question 7

What are the motor and sensory functions of the musculocutaneous nerve

Answer 7

Motor - brachialis, biceps brachii, coracobrachialis

Sensory - innervates lateral half of anterior forearm and small lateral portion of of posterior forearm

Question 8

What are the motor and sensory functions of the axillary nerve

Answer 8

Motor - teres major, deltoid

Sensory - gives off superolateral cutaneous nerve of arm innervating inferior region of deltoid

Question 9

What are the motor and sensory functions of the median nerve

Answer 9

Motor - flexor muscle in forearm, thenar muscles, two lumricals that move index and middle fingers

Sensory - plamar cutaneous innervates lateral part of palm, digital cutaneous innervates lateral three and a half fingers on palmar surface

Question 10

What are the motor and sensory functions of the radial nerve

Answer 10

Motor - triceps brachii and extensor muscles in posterior arm compartment

Sensory - posterior aspect of arm and forearm, posterolateral aspect of hand

Question 11

What are the motor and sensory functions of the ulnar nerve

Answer 11

Motor - muscles of hand (except thenar and two lateral lumbricals), flexor carpi ulnaris, medial half of flexor digitorum profundus

Sensory - anterior and posterior surfaces of medial one and a half fingers and associated palm area

Question 12

What divisions form the axillary and radial nerve and which compartment do they innervate

Answer 12

Posterior divisions

Supply extensor (posterior) compartments

Question 13

What divisions form the ulnar, median and musculocutaneous nerves and what compartment do they supply

Answer 13

Anterior divisions

Supply flexor (anterior) compartments

Question 14

Where are the types of brachial plexus injuries

Answer 14

Upper and lower

Question 15

What do upper brachial plexus injuries result from and how might this occur

Answer 15

Excessive increase in angle between neck and shoulder

Trauma or during birth of baby if should becomes impacted in pelvis with excessive traction is applied to the neck

Question 16

What nerve roots are affected in upper brachial plexus injuries and what movements are affected

Answer 16

C5 - shoulder abduction and external rotation

C6 - elbow flexion, wrist extension and supination

Question 17

What do lower brachial plexus injuries result from

Answer 17

Forced hyperextension or hyperabduction

Question 18

What nerve roots are affected in lower brachial plexus injuries and which movements are affected

Answer 18

C8 - finger flexion and extension

T1 - finger abduction and adduction

Question 19

What are injuries to the upper and lower brachial nerve roots called

Answer 19

Upper - Erb’s palsy

Lower - Klumpke’s palsy