Muscles of the Upper Arm

Question 1

How many muscles are located within the upper arm?

Answer 1

4

Question 2

Which muscles make up the Anterior compartment of the upper arm?

Answer 2

Biceps Brachii, Brachialis, Coracobrachialis.

Question 3

What muscles lies in the Posterior compartment of the upper arm?

Answer 3

Triceps Brachii.

Question 4

What is the Bicipital aponeurosis?

Answer 4

Its a sheet of connective tissue given off as the tendon of the bicep brachii enters the forearm. It forms the roof of the cubital fossa, and blends with the deep fascia of the anterior forearm.

Question 5

Where is the origin of Biceps Brachii?

Answer 5

Long head originates from the supraglenoid tubercle of the scapula, and the short head originates from the coracoid process of the scapula.

Question 6

Where does Biceps Brachii insert?

Answer 6

Both heads insert distally into the radial tuberosity and the fascia of the forearm via the bicipital aponeurosis.

Question 7

What is the function/action of Biceps Brachii?

Answer 7

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

Question 8

What innervates Biceps Brachii?

And what does the biceps tendon reflex actually test?

Answer 8

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

Question 9

Where is the origin of Coracobrachialis?

Answer 9

Originates from the coracoid process of the scapula.

Question 10

Where does Coracobrachialis insert?

Answer 10

The muscle passes through the axilla, and attaches the medial side of the humeral shaft, at the level of the deltoid tubercle.

Question 11

What is the function/action of Coracobrachialis?

Answer 11

Flexion of the arm at the shoulder, and weak adduction.

Question 12

What innervates Coracobrachialis?

Answer 12

Mucocutaneous nerve.

Question 13

Where is the origin of Brachialis?

Answer 13

Originates from the medial and lateral surfaces of the humeral shaft.

Question 14

Where does Brachialis insert?

Answer 14

Into the ulna tuberosity, just distal to the elbow joint.

Question 15

What is the action/function of Brachialis?

Answer 15

Flexion at the elbow.

Question 16

What innervates Coracobrachialis?

Answer 16

Musculocutaneous nerve, with contributions from the radial nerve.

Question 17

What is the arterial supply of the anterior compartment of the upper arm?

Answer 17

Arterial supply to the anterior compartment of the upper arm is via muscular branches of the brachial artery.

Question 18

What is the arterial supply to the Posterior compartment of the arm?

Answer 18

Arterial supply to the posterior compartment of the upper arm is via the profunda brachii artery.

Question 19

Where is the origin of Triceps Brachii?
Long head-
Lateral head-
Medial head-

Answer 19

Long head – originates from the infraglenoid tubercle. Lateral head – originates from the humerus, superior to the radial groove. Medial head – originates from the humerus, inferior to the radial groove.

Question 20

Where does Triceps Brachii insert?

Answer 20

Distally, the heads converge onto one tendon and insert into the olecranon of the ulna.

Question 21

What is the action/function of Triceps Brachii?

Answer 21

Extension of the arm at the elbow.

Question 22

What innervates Triceps Brachii?

Answer 22

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