The dorsal interosseous muscle (DIM) may be indicated in the coverage of small defects of the hand as a proximally or distally based muscle flap. The objective of his two-part study was to define the vascular supply of the interosseous muscles of the hand, and to identify the dominant arterial pedicle of each muscle for potential use of these muscles as muscle or musculocutaneous flaps. A radio-opaque injectate (lead oxide, gelatin and water mixture) was injected into the femoral artery of 10 fresh cadavers. The intrinsic muscles of the hand were meticulously dissected along with their vascular pedicles, removed and radiographed. The number, type, diameter of vascular pedicles of muscles and their distribution were analyzed. The area of the vascular territory supplied by each source vessel was calculated. Ten embalmed cadavers were injected with red latex into their axillary arteries and a similar dissection protocol was followed. Vascularisation of the interosseous muscles is by palmar metacarpal arteries of the deep palmar arterial arch and dorsal metacarpal arteries. In addition to these constant axial blood supplies, there are rich perimuscular plexus from adjacent nutrient arteries. The origins and insertions of the muscles are also supplied by very fine vessels from this plexus. The diameters of the dominant branches ranged from 0.6 to 1.4 mm (mean 1.0 mm). The vascular territories of the dorsal metacarpal and common palmar arteries extend along the medial and lateral parts of the dorsal interosseous muscles. The dorsal interosseous muscle or musculocutaneous flap are more useful than other intrinsic muscles of the hand because the DIM are easily accessible via the dorsal hand and can be split distally or proximally, and a split musculosseous flap based proximally or distally on the dorsal metacarpal artery can be performed. The functional defect in the donor site after an interosseous muscle flap transfer of the second and third interosseous space is tolerable. This anatomic study provides further information to help design various flaps from the hand for local transfer. The authors describe a thirty-two-year-old male patient in whom the third dorsal interosseous muscle was used as a distally based myocutaneous flap to reconstruct a defect in the hand.
