As in the arm, the forearm is divided into anterior and posterior compartments (Fig. 7.79). In the forearm, these compartments are separated by: a lateral intermuscular septum, which passes from the anterior border of the radius to deep fascia surrounding the limb; an interosseous membrane, which links adjacent borders of the radius and ulna along most of their length; and the attachment of deep fascia along the posterior border of the ulna.