Brachial Plexus

Question 1

What muscles does the axillary nerve innervate?

Answer 1

Teres minor and deltoid muscle

Question 2

What muscle does the musculocutaneous nerve innervate?

Answer 2

Muscles of the anterior portion of the arm (brachialis, coracobrachialis, and biceps brachii)

Question 3

What muscles does the median nerve innervate?

Answer 3

Muscles of the anterior compartment of the forearm flexors ; except: medial half of flexor digitorum profundus and flexor carpi ulnaris

Question 4

What muscles does the ulnar nerve innervate?

Answer 4

Medial half of flexor digitorum profundus and flexor carpi ulnaris

Question 5

What muscles does the radial nerve innervate?

Answer 5

All muscles in the posterior compartment of forearm extensors AND triceps brachii

Question 6

What are the 3 trunks?

Answer 6

1. Superior trunk (arises from C5 + C6)
2. Middle trunk (arises from C7)
3. Inferior trunk (arises from C8 + T1)

Question 7

What are the 3 cords?

Answer 7

Lateral cord, medial cord, and posterior cord

Question 8

What trunks and divisions form the lateral cord?

Answer 8

Anterior division of superior trunk and anterior division of middle trunk (C5 - C7)

Question 9

What trunks and divisions form the posterior cord?

Answer 9

All posterior divisions of each trunk (C5-T1)

Question 10

What trunks and divisions form the medial cord?

Answer 10

Anterior division of the inferior trunk

Question 11

What non-terminal nerves branch from superior trunk?

Answer 11

Long thoracic n., Dorsal scapular n., suprascapular n., nerve to subclavius, and lateral pectoral nerve (only nerve after divisions/in cord portion).

Question 12

What non-terminal nerves branch from middle trunk?

Answer 12

Upper subscapular, thoracodorsal, lower subscapular

Question 13

What non-terminal nerves branch from inferior trunk?

Answer 13

Medial pectoral nerve, medial brachial cutaneous n., and medial ante-brachial cutaneous n.

Question 14

What terminal nerves branch from lateral cord?

Answer 14

Musculocutaneous and contributes to median nerve

Question 15

What terminal nerves branch from posterior cord?

Answer 15

Radial Nerve + Axillary Nerve

Question 16

What terminal nerves branch from medial cord?

Answer 16

Ulnar nerve and contributes to median nerve

Question 17

What does the long thoracic nerve run parallel with?

Answer 17

Lateral Thoracic Artery

Question 18

What causes winged scapula?

Answer 18

Paralysis of serratus anterior and damage to long thoracic nerve (C5-C7)

*seen after radical masectomy

Question 19

What causes Erb-Duchenne Palsy?

Answer 19

Lesion in superior trunk (C5+C6) of brachial plexus

Question 20

What causes Klumpke Palsy (claw hand)?

Answer 20

-Lower brachial plexus injury (C8+T1)
….C8 and T1 forms inferior trunk… which forms medial cord… contributes to median nerve + ulnar nerve (SO MEDIAN + ULNAR NERVES are affected).

-Horner’s syndrome may be associated