Arising in common with the extensor digitorum the belly of the muscle separates after some distance and then becomes tendinous. Passing beneath the extensor retinaculum on the dorsal aspect of the radioulnar joint the tendon usually splits into two which lie side by side on the fifth metacarpal bone as they pass to the little finger. The tendon of extensor digitorum communis to the little finger commonly joins them by a band near the metacarpophalangeal joint. It becomes an expansion on the dorsum of the little finger, behaving as the other extensor expansions. Do not be confused by the double tendon of extensor digiti minimi and think that one of the tendons belongs to extensor digitorum — it doesn’t! The digitorum connexion is the band near the metacarpophalangeal joint.
Nerve supply of extensor digiti minimi:
By the posterior interosseous nerve (C7, 8) in the forearm.
Action of extensor digiti minimi:
As the name indicates, it acts as extensor of the little finger.