Posterior compartment of the forearm Posterior compartment of the forearm The posterior compartment of the forearm (or extensor compartment) contains twelve muscles which are chiefly responsible for extension of the wrist and digits, and supination of the forearm. It is separated from the anterior compartment by the interosseous membrane between the radius and ulna. There are generally twelve muscles in the posterior compartment of the forearm, which can be further divided into a superficial, intermediate, and deep layer. Most of the muscles in the superficial and the intermediate layers share a common origin which is the outer part of the elbow, the lateral epicondyle of
Medial cutaneous nerve of forearm to the back of the forearm, and descends on its ulnar side as far as the wrist, distributing filaments to the skin. It communicates with the medial brachial cutaneous, the dorsal antebrachial cutaneous branch of the radial, and the dorsal branch of the ulnar. Medial cutaneous nerve of forearm The medial antebrachial cutaneous nerve (internal cutaneous nerve, medial cutaneous nerve of forearm) arises from the medial cord of the brachial plexus. It derives its fibers from the eighth cervical and first thoracic nerves, and at its commencement is placed medial to the axillary artery. It gives off, near the axilla,