Innervation of the metacarpophalangeal and interphalangeal joints: a microanatomic and histologic study of the nerve endings.

Six pairs of fresh human cadaver hands were dissected under the surgical microscope at x28 to x32 and selectively silver stained. In addition, 18 proximal interphalangeal and metacarpophalangeal joints of fresh cadaver hands were processed with protein gene product 9.5 for measurement and analysis of nerve endings in those joints. The results demonstrated that the proximal interphalangeal joints are innervated by 2 palmar articular nerves (mean diameter, 0.21-0.53 mm). Each metacarpophalangeal joint of the second through fifth fingers is predominantly supplied by 1 palmar articular nerve (mean diameter, 0.41-0.59 mm), which comes from the deep branches of the ulnar nerve, as well as by 2 dorsal articular nerves (mean diameter, 0.11-0.24 mm). The metacarpophalangeal joint of the thumb also had 2 dorsal articular nerves (mean diameter, 0.18-0.24 mm) and 2 palmar joint nerves (mean diameter, 0.29-0.31 mm). The mean densities of the type IV free nerve endings and the mean numbers of the encapsulated endings in the palmar capsules were consistently much greater than in the dorsal or lateral capsules. The majority of encapsulated endings were pacinian corpuscles. The anatomic and histologic information may help the surgeon avoid damaging these small joint nerves during operative procedures and to reconstruct or de-innervate them if necessary. (J Hand Surg 2000; 25A:128-133. Copyright 2000 by the American Society for Surgery of the Hand.).