Chapter 3A (Axilla and Brachial Plexus Nerves and Origin)

Question 1

Lateral Pectoral

Answer 1

Origin: Side branch of lateral cord, receiving fibers from C5, C6, C7

Structures Innervated: Primarily pectoralis major

Question 2

Musculocutaneous

Answer 2

Origin: Terminal branch of lateral cord, receiving fibers from C5-C7

Structures: Muscles of anterior compartment of arm (coracobrachiialis, biceps brachii and brachialis); skin of lateral aspect of forearm

Question 3

Median

Answer 3

Origin: Lateral root of median nerve is a terminal branch of lateral cord; Medial root of median nerve is a terminal branch of medial cord

Structures: Muscles of anterior forearm compartment (except for flexor carpi ulnaris and ulnar half of flexor digitorum profundus)

Question 4

Medial pectoral

Answer 4

Origin: Side branches of medial cord, receiving fibers from C8 and T1

Structures: Pectoralis minor and sternocostal part of pectoralis major

Question 5

Medial cutaneous nerve of arm

Answer 5

Origin: Side branches of medial cord, receiving fibers from C8 and T1

Structures: Skin of medial side of arm, as far distal as medial epicondyle of humerus and olecranon of ulna

Question 6

Medial cutaneous nerve of forearm

Answer 6

Origin: Side branches of medial cord, receiving fibers from C8 and T1

Structures: Skin of medial side of forearm, as far distal as wrist

Question 7

Ulnar

Answer 7

Origin: Larger terminal branch of medial cord, receiving fibers from C8, T1,

Structures: Flexor carpi ulnaris and ulnar half of flexor digitorum profundus (forearm); most intrinsic muscles of hand

Question 8

Upper subscapular

Answer 8

Origin: Side branch of posterior cord, receiving fibers from *C5

Structures: Superior portion of subscapularis

Question 9

Lower subscapular

Answer 9

Origin: Side branch of posterior cord receiving fibers from *C6

Structures: Inferior portion of subscapularis and teres major

Question 10

Thoracodorsal

Answer 10

Origin: Side branch of posterior cord, receiving fibers from C6, *C7, and C8

Structures: Latissimus dorsi

Question 11

Axillary

Answer 11

Origin: Terminal branch of posterior cord, receiving fibers from *C5 and C6

Structures: Glenohumeral (shoulder) joint; teres minor and deltoid muscles

Question 12

Radial

Answer 12

Origin: Larger terminal branch of posterior cord (largest branch of plexus), receiving fibers from C5-T1

Structures: All muscles of posterior compartments of arm and forearm