Muscles of the upper arm

Question 1

What are the muscles of the anterior compartment of the upper arm?

Answer 1

Biceps, coracobrachialis and brachialis

Question 2

Innervation to anterior compartment of the upper arm

Answer 2

Musculocutaneous nerve

Question 3

Arterial supply to the anterior compartment of the upper arm

Answer 3

Muscular branches of the brachial artery

Question 4

Biceps brachii attachments

Answer 4

Long head origionates from the supraglenoid tubercle of the scapula, and the short head origionates from the coracoid precess of the scapula. Both heads insert distally into the radial tuberosity and the fascia of the forearm via the biceptial aponeurosis.

Question 5

Biceps brachii function

Answer 5

Supination of the forearm. It also flexes the arm at the elbow and at the shoulder.

Question 6

Biceps brachii innervation

Answer 6

Musculocutaneous nerve. The biceps tendon reflex tests spinal cord segment C6.

Question 7

Coracobrachialis attachments

Answer 7

Origionates from the coracoid process of the scapula. The muslce passes through the axilla , and attaches the medial side of the humeral shaft, at the level of the deltiod tubercle.

Question 8

Coracobrachialis function

Answer 8

Flexion of the arm at the shoulder and weak adduction.

Question 9

Coracobrachialis innervation

Answer 9

Musculocutaneous nerve

Question 10

Brachialis attachments

Answer 10

Origionates from the medial and lateral surfaces of the humeral shaft and inserts into the ulna tuberosity, just distal to the elbow joint.

Question 11

Brachialis function

Answer 11

Flexion at the elbow

Question 12

Brachialis innervation

Answer 12

Musculocutaneous nerve

Question 13

Posterior compartment of the upper arm

Answer 13

Contains the triceps brachii muscle, which has three heads. The medial head lies deeper than the other two which cover it.

Question 14

Arterial supply to posterior compartment of the upper arm

Answer 14

Profunda brachii artery

Question 15

Triceps brachii attachments

Answer 15

• Long head - origionates from the infraglenoid tubercle.
• Lateral head - origionates from the humerus, superior to the radial groove.
• Medial head - origionates from the humerus, inferior to the radial groove.
• Distally, the heads converge into one tendon and insert into the olecranon of the ulna.

Question 16

Triceps brachii function

Answer 16

Extension of the arm at the elbow

Question 17

Triceps brachii innervation

Answer 17

Radial nerve. A tap on the triceps tendon tests spinal segment C7. In some individuals, the long head of the triceps brachii is innervated by the axillary nerve.