Functional gliding spaces of the dorsal side of the human hand

The clinical and functional importance of gliding spaces of the hand (e.g., their role in the spread of infection or as a consideration in reconstructive surgery) has been repeatedly emphasized. However, only a few studies have provided details regarding the connective tissue spaces in the metacarpal region of the dorsal side of the human hand. The aim of the present study was to analyze the morphology and elucidate the anatomic relation of functional gliding spaces in the metacarpal region on the dorsal side of the human hand in order to provide a better understanding of function, and of clinical disorders and their treatment. To delineate these spaces we used a plastic (Acrifix 90) injection method. Twenty fixed and unfixed cadaver hands were subcutaneously injected with Acrifix 90 (a methacrylate) into the metacarpophalangeal transitional region and into the tendon sheaths of the extensor muscles. Different colors were used to distinguish one injected plastic solution from another. The spreading pattern of the injected medium was analyzed by careful dissection. To delineate the exact bordering structures and the topography of the injected spaces, two hands were plastinated using the E12/E6 technique (von Hagens et al., Anat Embryol 1987;175:411-421), and one hand was injected and embedded in Technovit 7100 for histological investigations. Injecting the plastic into the metacarpophalangeal transitional region of fingers II-IV in a disto-proximal direction, the solution spreads along the surface of the separate extensor tendons. It then coalesces 1-2 cm proximal to the injection points to form a continuous plastic plate, which protrudes between and on top of the previous injected tendon sheaths. In no case was a communication between the paratendinous tissue and the tendon sheaths observed. Laterally, the injected solution is delimited at the radial side of the extensor tendon of the second finger and at the ulnar side of the extensor tendon of the fourth finger. Using the described technique at the fifth finger yields a plastic plate that extends from the injection point to the tendon sheath. However, in two specimens a connection between the plastic injected into the tendon sheath of the fifth finger, and the distal injected solution was observed.