forearms

Forearms are the paired structures of the upper limb between the elbow and the wrist. They contain two long bones, the radius and the ulna, which run parallel in the forearm and are joined by an interosseous membrane. The radius lies on the thumb side and the ulna on the little finger side; together they enable rotation of the forearm at the proximal and distal radioulnar joints, producing pronation and supination. The forearm also forms part of the radiocarpal region where it interfaces with the wrist.

Anatomy and compartments

The forearm is divided into an anterior (flexor-pronator) compartment and a posterior (extensor-supinator) compartment by fascial septa. The muscles of the anterior compartment primarily flex the wrist and fingers and pronate the forearm, while the posterior compartment muscles extend the wrist and fingers and supinate the forearm. Innervation follows the regional pattern: the median nerve supplies most of the flexors (with the ulnar nerve providing the flexor carpi ulnaris and part of the flexor digitorum profundus), and the radial nerve supplies the extensor muscles. The arteries of the forearm are the radial and ulnar arteries, with contributions from the common interosseous artery.

Function and clinical notes

Forearm muscles enable a wide range of movements at the elbow, wrist, and fingers, including grip, rotation, and subtle wrist actions required for daily tasks. Clinically, forearm injuries commonly involve fractures of the radius and/or ulna and may affect the proximal or distal radioulnar joints. Classic injury patterns include Monteggia fractures (proximal ulna with radial head dislocation) and Galeazzi fractures (distal radius fracture with distal radioulnar joint disruption). Tendinopathies of the elbow and forearm extensor or flexor tendons and nerve injuries (affecting median, radial, or ulnar nerves) are also encountered.