The muscular belly of extensor digiti IV proprius goes from the middle of the forearm to the proximal part of the carpal where its tendon passes along with the tendon of the extensor digiti V proprius through the more lateral compartment that forms the extensor retinaculum, and enters into the abaxial part of the dorsal extensor expansion that form at the level of the metacarpophalangeal joint of the digit IV (Fig.
Its muscular belly is in the two proximal thirds of the forearm, and develops a tendon to distal that inserts into the abaxial part of the dorsal extensor expansion of the digit V (Fig.
Extensor digiti IV proprius (1), Extensor digiti V proprius (2), Extensor digitorum communis (3), its tendons (1', 2', 3'), Retinaculum extensor (4), Dorsal extensor expansion (5).
In lateral band insertion surgeries the transferred tendon is inserted into the lateral bands (ulnar side of middle, ring and little finger and radial side of index finger) of the extensor expansion
of each digit.
On the dorsum of the hand, opposite the heads of the second and third metacarpal bones, the two tendons of the El joined the ulnar sides of the tendons of the ED, enhancing the medial slips of the extensor expansion (EE) for the second and third digits (Figure 2).
By equalizing the thickness of the medial slips of the extensor expansion, the two tendons of the El may assist with the balancing of the mechanical stresses within the extensor expansion, contributing to the coordination of the extension of the second and third digits.
No % No % No % 1 35 87.5 0 0 0 0 2 40 100 0 0 0 0 3 34 85 5 12.5 1 2.5 4 35 87.5 2 5 1 2.5 Extensor expansion and base of Proximal proximal phalanx phalanx Lumbrical muscle No.
In 5 specimens (10%) they are inserted into base of first phalanx and extensor expansion. Bary J.
The adductors of the thumb insert onto the extensor expansion
through its aponeurosis, which lies superficial to the ulnar collateral ligament.
This was described as bringing the long and short flexors along the lateral aspects of the proximal phalanx and suturing them to the extensor expansion. (11) Modifications were made to the original procedure, one of which was to bring the long flexor through a drill hole in the neck of the proximal phalanx.
Their study demonstrated that transfer of the FDL to the extensor expansion could restore the load and displacement curves of the unstable second MTPJ to that of the normal toe.
The transmission of force from the interosseus and lumbrical muscles through the extensor expansion
and the action of the retinacular ligaments were approximated based on relationships presented in the literature (Micks & Reswick, 1981).