The Tendons on the Dorsum of the Hand*

Anomalous Extensor Tendons to the Long Finger: A Cadaveric Study of Incidence

“…This is in marked contrast to the previously reported incidence of 2% to 7%. 2,5,[7][8][9]11 The EIMC insertion onto the long finger was typically central and palmar in relation to the EDC tendon. As with the EMP specimens, only 1 specimen had an EIMC that inserted distal to the MCP joint.…”

“…[1][2][3][4][5][6][7][8] The EDBM has a distal-lying muscle belly on the hand, whereas the EIMC muscle belly is entirely in the forearm. The extensor medii proprius (EMP) is another anomalous muscle that takes its origin from the dorsal forearm compartment, adjacent to the extensor indicis proprius (EIP), and inserts onto the long finger.…”

“…9 The EIMC has a reported incidence of 2% to 7%, whereas the EDBM is present in 1% to 3% of hands. 2,5,[7][8][9][11][12][13] In previous studies, all EMP muscle origins were distal and ulnar to the origin of the EIP muscle belly, and insertions were into the dorsal aponeurosis of the long finger. 9, 14 The EIMC has been described as an EIP that splits and inserts into both the long and index fingers.…”

“…9, 14 The EIMC has been described as an EIP that splits and inserts into both the long and index fingers. 2,5 We performed a systematic cadaveric dissection to test the hypotheses that (1) the incidence of EMP and EIMC tendons to the long finger are greater than previously reported and (2) the insertion of the EMP might be more variable than reported.…”

Extensors of the hand

“…The multiple tendon slips have even been documented to insert onto the thumb, middle, or ring fingers. 7,9 Wood 13 termed the EIP muscle that attached to the middle and ring fingers as the extensor medii proprius. 14 The incidence of the extensor medii proprius (or extensor indicis et medii) is between 2--5%.…”