Antebrachial region

The antebrachial region, commonly known as the forearm, constitutes the segment of the upper limb extending from the elbow (cubital region) proximally to the wrist (carpal region) distally. It can be divided into anterior (flexor) and posterior (extensor) regions that relate to the anterior and posterior compartments of the forearm. This compartmentalization is achieved by the presence of the radius and ulna bones, the connecting interosseous membrane spanning between them, and invaginations of the deep fascia (the antebrachial fascia) that encircle the entire forearm and send septa inwards.

• The anterior region or anterior compartment contains muscles responsible for flexion of the wrist and fingers, as well as pronation of the forearm. These muscles receive their main innervation from the median nerve and, to a lesser extent, the ulnar nerve.

• Conversely, the posterior region or posterior compartment contains muscles responsible for extension of the wrist and fingers, and supination of the forearm. This group of muscles is predominantly innervated by the radial nerve.

The external boundaries of the forearm (or antebrachium) are delineated by the prominent subcutaneous surface of the ulna medially, and the subcutaneous surface of the radius along with the brachioradialis muscle laterally. The robust antebrachial fascia not only envelops the entire region but also contributes to the formation of intermuscular septa, which further separate the compartments.