Brachial plexus

Question 1

What are the roots of the superior, middle and inferior trunk?

Answer 1

Superior: C5, C6
Middle: C7
Inferior: C8, T1

Question 2

What is the lateral, posterior and medial cords formed from?

Answer 2

Lateral: Anterior division of superior and middle trunks
Posterior: posterior divisions of superior, middle and inferior trunks
Middle: Anterior division of inferior trunk

Question 3

From what part of the brachial plexus is the musculocutaneous nerve formed from?

Answer 3

Lateral cord

C5, C6, C7

Question 4

From what part of the brachial plexus is the axillary nerve formed from?

Answer 4

Posterior cord of superior trunk

C5, C6

Question 5

From what part of the brachial plexus is the median nerve formed from?

Answer 5

Formed from lateral and medial cords

C6-T1

Question 6

From what part of the brachial plexus is the radial nerve formed from?

Answer 6

Posterior cord of all trunks

C5-C8, T1

Question 7

From what part of the brachial plexus is the ulnar nerve formed from?

Answer 7

Formed from medial cord

C8, T1

Question 8

What are the minor branches coming off the roots of the brachial plexus?

Answer 8

Dorsal scapular nerve

Long thoracic nerve

Question 9

What are the minor branches coming off the trunks of the brachial plexus?

Answer 9

Suprascapular nerve

Nerve to subclavius

Question 10

What are the minor branches coming off the lateral cord of the brachial plexus?

Answer 10

Lateral pectoral nerve

Question 11

What are the minor branches coming off the medial cord of the brachial plexus?

Answer 11

Medial pectoral nerve
Medial cutaneous nerve of arm
Medial cutaneous nerve of forearm

Question 12

What are the minor branches coming off the posterior cord of the brachial plexus?

Answer 12

Superior subscapular
Thoracodorsal
Inferior subscapular

Question 13

What is ‘Erb’s palsy’?

Answer 13

Upper brachial plexus injury: excessive increase in angle of neck and shoulder caused by difficult birth or shoulder trauma.
Characteristic ‘waiter’s tip’
Affects nerves directly innervated by C5 and C6. (Musculocutaneous, Axillary, Suprascapular, Nerve to subclavius)

Question 14

What motor and sensory functions are impaired in Erb’s palsy?

Answer 14

Motor: Abduction of the shoulder, Flexion at the shoulder, Lateral rotation of the arm, Supination of the forearm

Sensory: Loss of sensation down lateral side of the arm

Question 15

What is Klumpke’s palsy’?

Answer 15

Lower brachial plexus injury: excessive abduction of the arm
Affects nerves of the T1 root, ulna and median nerves.
Clawed hand: hyperextended metacarpophalangeal joint and flexed interphalangeal joint.

Question 16

What motor and sensory functions are impaired in Klumpke’s palsy?

Answer 16

Motor: All small muscles of the hand
Sensory: Loss of sensation along medial side of the arm