Extensorit

Extensorit, or extensor muscles, are a group of muscles located in the posterior compartment of the forearm. They primarily extend the wrist and fingers and contribute to thumb movement. They originate mainly from the lateral epicondyle of the humerus via the common extensor tendon and insert on the dorsal surfaces of the hand and digits. The principal extensors include the extensor carpi radialis longus and brevis, extensor digitorum, extensor digiti minimi, extensor indicis, extensor carpi ulnaris, and the pollicis group (extensor pollicis longus and extensor pollicis brevis). Abductor pollicis longus also participates in thumb movement. Innervation is primarily by the radial nerve and its deep branch, the posterior interosseous nerve, with some variation among individual muscles (e.g., extensor carpi radialis longus is supplied by the radial nerve before branching to the posterior interosseous nerve).

Functionally, these muscles extend the wrist and digits at their joints and aid in thumb extension and abduction, contributing to hand stabilization during grip and dexterous tasks. They act as antagonists to the forearm flexors.

Clinical relevance includes overuse injuries such as extensor tendinopathies. Lateral epicondylitis (tennis elbow) involves tendinopathy at the origin of several extensor muscles and presents with lateral elbow pain worse with wrist extension. Extensor tendon injuries can occur after trauma, and posterior interosseous nerve compression can cause weakness of finger extension without sensory loss. Diagnosis relies on history and physical examination, with imaging used to assess structural abnormalities; treatment ranges from activity modification and physical therapy to injections or, rarely, surgery.