extensorsupinator

Extensor-supinator is not a formal anatomical term in standard anatomy. It is sometimes used informally to describe a functional grouping of forearm muscles that contribute to extension of the wrist and fingers, and that may assist in supination of the forearm. In strict terminology, the extensor muscles form the posterior compartment of the forearm and extend the wrist and digits, while the supinator is a distinct muscle whose primary action is to supinate the forearm.

The extensor compartment includes several muscles, such as the extensor carpi radialis longus and brevis, extensor digitorum, extensor indicis, extensor digiti minimi, extensor carpi Ulnaris, and the thumb extensors, including extensor pollicis longus and extensor pollicis brevis. These muscles generally originate from the lateral epicondyle of the humerus and insert on the posterior aspects of the hand and fingers. The supinator originates from the lateral epicondyle of the humerus and ulna and wraps around the proximal radius to insert on its shaft, acting to rotate the forearm from a pronated position to a supinated one.

Innervation for the extensor group is primarily via the radial nerve, with many of the deep-level extensors supplied by branches of the posterior interosseous nerve. The supinator receives its nerve supply from the deep branch of the radial nerve. Blood supply to these muscles comes from branches of the radial and interosseous arteries, as well as nearby arterial networks.

Clinically, radial nerve injury can produce wrist drop and impaired finger extension, while selective injury to the posterior interosseous nerve can weaken finger and thumb extension. Supination weakness can accompany injuries impacting the supinator.