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 mi croscope at x 28 to x 32 and selectively silver stained. In addition, 18 pr oximal interphalangeal and metacarpophalangeal joints of fresh cadaver hand s were processed with protein gene product 9.5 for measurement and analysis of nerve endings in those joints. The results demonstrated that the proxim al interphalangeal joints are innervated by 2 palmar articular nerves (mean diameter, 0.21-0.53 mm). Each metacarpophalangeal joint of the second thro ugh fifth fingers is predominantly supplied by 1 palmar articular nerve (me an 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 m m). 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 diamet er, 0.29 -0.31 mm). The mean densities of the type IV free nerve endings an d the mean numbers of the encapsulated endings in the palmar capsules were consistently much greater than in the dorsal or lateral capsules. The major ity of encapsulated endings were pacinian corpuscles. The anatomic and hist ologic information may help the surgeon avoid damaging these small joint ne rves during operative procedures and to reconstruct or deinnervate them if necessary. Copyright (C) 2000 by the American Society for Surgery of the Ha nd.