Compartments of the arm and forearm

Question 1

Describe the compartments of the upper arm;

Answer 1

Due to the many insertion onto the upper humerus the deltoid region has no defined compartments. Below this the brachium can be divided into Ant. (flexor) and Post. (Extensor) compartments.

These are formed by medial and lateral intermuscular septa.

Question 2

Describe the lateral and medial intermuscular septa of the arm;

Answer 2

These septa are attatched to the medial and lateral supracondylar ridges of the humerus, fading out in the upper arm.

Continuous with the deep fascia.

Question 3

Which nerve innervates the anterior compartment of the arm and describe its path;

Answer 3

The musculocutaneous n.

It pierces the coracobrachialis nerve, then lies on the brachialis.

Innervates; Coracobrachialis, biceps brachii, brachialis.

Question 4

Do the median or ulnar nerve branch in the arm?

Answer 4

No they have no branches in the arm.

Question 5

Does the axillary nerve innervate the arm?

Answer 5

Yes. It wraps around the posterior aspect of the surgical neck of humerus and innervates deltoid + teres minor.

Question 6

What is the nerve and blood supply of the posterior compartment?

Answer 6

Post. compartment is occupied by the triceps brachii.

Nerve = Radial
Blood = Branches of the profunda brachii artery.

Question 7

Describe the compartments of the lower arm;

Answer 7

Ant.
Post.
Medial (Ext. of forearm) and lateral (flexors of forearm) compartments form in the lower aspects of the arm. These are formed by lateral and medial intermuscular speta.

Question 8

What are found on the epicondyles of the humerus;

Answer 8

Lateral epicondyle gives rise to the common extensor tendon of the forearm.

Medial epicondyle gives rise to the common flexor tendon of the forearm.