extensor digital expansion(redirected from extensor aponeurosis)
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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.