Bilateral extensor medii proprius with split tendon of extensor indicis proprius, a rare anatomical variant.

The extensor medii proprius (EMP) is anomalous extensor muscle of the hand. During the routine dissection of a 78-year-old Chinese male cadaver, bilateral EMP and extensor indicis proprius (EIP) were observed in the upper limbs. The EMP originated from the distal third of the ulna and its tendon was inserted into the dorsal aponeurosis of the middle finger on both hands. The tendon of EIP was split into two slips on the dorsum of hand and inserted to the radial and ulnar side of the extensor digitorium communis (EDC)-index, respectively. Awareness of such anatomical variations in the extensor compartment of the forearm could help in the identification and repair of these structures.