extensor digital expansion

ex·ten·sor dig·i·tal ex·pan·sion

a triangular tendinous aponeurosis including the tendon of the extensor digitorum centrally, interosseus tendons on each side, and a lumbrical tendon laterally. It covers the dorsal aspect of the metacarpophalangeal joint and the proximal phalanx. Synonym(s): dorsal hood, extensor aponeurosis, extensor expansion