Fascial compartments of arm

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Fascial compartments of arm
Braus 1921 165.png
Cross section showing the fascial compartments of the upper and lower arm
TA A04.6.01.001
FMA 265176
Anatomical terminology

The limbs of the human body, can be divided into segments, such as the arm and the forearm of the upper limb, and the thigh and the leg of the lower limb. If these segments are cut transversely, it is apparent that they are divided into multiple sections, called fascial compartments, and are formed by tough connective tissue septa. The upper arm is divided into two compartments, an anterior and a posterior, by the lateral intermuscular septum and the medial intermuscular septum.

Intermuscular septa[edit]

The lateral intermuscular septum extends from the lower part of the crest of the greater tubercle of the humerus, along the lateral supracondylar ridge, to the lateral epicondyle; it is blended with the tendon of the deltoid muscle, gives attachment to the triceps brachii behind, and to the brachialis, brachioradialis, and extensor carpi radialis longus muscles in front. It is perforated by the radial nerve and profunda branch of the brachial artery.

The medial inter muscular septum, is thicker than the lateral intermuscular septum. It extends from the lower part of the crest of the lesser tubercle of the humerus below the teres major, and passes along the medial supracondylar ridge to the medial epicondyle; it is blended with the tendon of the coracobrachialis, and gives attachment to the triceps brachii behind and the brachialis in front.

It is perforated by the ulnar nerve, the superior ulnar collateral artery, and the posterior branch of the inferior ulnar collateral artery.

Anterior compartment[edit]

Anterior (at top) and posterior (at bottom) compartments

The anterior compartment of the arm is also known as the flexor compartment of the arm as its main action is that of flexion. The anterior compartment is one of the two anatomic compartments of the upper arm, the other being the posterior compartment.

The anterior compartment contains three muscles; the biceps brachii, the brachialis and the coracobrachialis. These muscles are all innervated by the musculocutaneous nerve[1]which arises from the fifth, sixth and seventh cervical spinal nerves. The blood supply is from the brachial artery.

Posterior compartment[edit]

The posterior compartment of the arm is also known as the "extensor compartment", as its main action is extension.

The muscles of this compartment are the triceps brachii and anconeus muscle and these are innervated by the radial nerve. Their blood supply is from the profunda brachii.

The triceps brachii is a large muscle containing three heads a lateral, medial, and middle. The anconeus is a small muscle that stabilizes the elbow joint during movement. Some embryologists consider it as the fourth head of the triceps brachia as the upper and lower limbs have similar embryological origins, and the lower limb contains the quadriceps femoris muscle which has four heads, and is the lower limb equivalent of the triceps.

See also[edit]


  1. ^ lesson4nervesofant&postarm at The Anatomy Lesson by Wesley Norman (Georgetown University)

External links[edit]

msk/arm[ dead link ] at the Memorial University of Newfoundland