Anterior Compartment of the Arm and Musculocutaneous Nerve

Question 1

Answer 1

Question 2

Answer 2

1. biceps brachii
2. brachialis
3. musculocutaneous nerve
4. coracobrachialis

Question 3

what is the most superficial muscle of the anterior compartment of the upper limb?

Answer 3

The biceps brachii is the most superficial muscle of the anterior compartment.

Question 4

what is the origin and insertion of biceps brachii?

Answer 4

It arises from the scapula via. two heads. Both heads unite at the distal third of the upper arm forming a short tendon which inserts onto the radial tuberosity.
It also attaches through the bicipital aponeurosis to the deep fascia of the forearm

Question 5

where does the short head of the biceps brachii muscle originate from?

Answer 5

coracoid process of the scapula

Question 6

where does the long head of the biceps muscle originate from?

Answer 6

The long head of the biceps muscle originates from the supraglenoid tubercle of the scapula. Its tendon passes through the shoulder joint and runs down the bicipital groove of the humerus.

Question 7

what is the action of the biceps muscle?

Answer 7

flexion of shoulder and elbow joint
- At the superior radio-ulnar joint it is involved in supination (the action in which the radius rotates over the ulna)

Question 8

what is the origin and insertion of the coracobrachialis muscle?

Answer 8

The coracobrachialis slender, rounded muscle passing from its origin at the tip of the coracoid process and inserting to the medial aspect of the mid-shaft of the humerus

Question 9

what is the action of the coracobrachialis muscle?

Answer 9

Its action is to flex the arm at the shoulder joint

Question 10

what is the origin and insertion of the brachialis muscle?

Answer 10

The brachialis muscle arises from the anterior surface of the distal shaft of the humerus. It is a deep muscle of the anterior compartment, passing downwards and attaching to the coronoid process of the ulna

Question 11

what is the main action of the brachialis muscle?

Answer 11

Its main action is to flex the elbow joint

Question 12

what does the musculocutaneous nerve arise from?

Answer 12

This nerve arises as a terminal branch from the lateral cord of the brachial plexus.

Question 13

what is the main nerve of the anterior compartment of the arm, supplying all the muscles within this compartment?

Answer 13

median nerve (except for the flexor carpi ulnaris and medial half of flexor digitorum profundus, which are innervated by the ulnar nerve)

Question 14

what is the course of the musculocutaneous nerve?

Answer 14

It enters the arm by perforating the coracobrachialis, descending distally between the biceps brachii and brachialis muscles. After crossing the elbow joint it gives off its terminal branch to supply the skin as the lateral cutaneous nerve of the forearm.

Question 15

What is the segmental or root value of the musculocutaneous nerve?

Answer 15

C5-7

Question 16

Does the musculocutaneous nerve supply any muscles in the forearm or hand?

Answer 16

Cutaneous innervation of the lateral forearm, but only motor innervation of muscles in the anterior compartment of the arm (coracobrachialis, biceps brachii, brachialis)
- so answer is no