Anterior Compartment of the Forearm

compartimentum antebrachii anterius

The anterior compartment of the forearm is the flexor-pronator compartment, lying in front of the radius, ulna and interosseous membrane. Its muscles are arranged in superficial, intermediate and deep layers and are supplied mainly by the median nerve, with flexor carpi ulnaris and half of flexor digitorum profundus supplied by the ulnar nerve.

Anatomical Data

Boundaries & Contents

Location	Front of the forearm.
Boundaries	Antebrachial fascia anteriorly Radius, ulna and interosseous membrane posteriorly Lateral intermuscular septum separating it from the lateral (mobile wad) muscles
Contents	Pronator teres Flexor carpi radialis, palmaris longus, flexor carpi ulnaris Flexor digitorum superficialis Flexor digitorum profundus Flexor pollicis longus Pronator quadratus Median nerve and anterior interosseous nerve Ulnar nerve and artery Radial artery

Biomechanics

Function & Actions

Holds the muscles that flex the wrist and fingers and pronate the forearm.

Clinical Relevance

Clinical Notes

This is the most common site of compartment syndrome in the upper limb, after distal radius, both-bone forearm and paediatric supracondylar fractures. The deep muscles, flexor digitorum profundus and flexor pollicis longus, are most at risk. Volar fasciotomy, often extended to release the carpal tunnel, is the treatment, and missed cases cause Volkmann contracture.

Pathology

Common Injuries & Conditions

Volar Forearm Compartment Syndrome

Raised pressure in the flexor compartment causing severe pain on passive finger extension, numbness and eventually muscle death if not decompressed.

Volkmann Ischaemic Contracture

Scarring and shortening of the deep forearm flexors after untreated compartment syndrome, leaving a clawed, flexed hand.

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