Innervation of the hand muscles of Didelphis marsupialis virginiana , Kerr

An investigation of the innervation of the hand muscles of the opossum, Didelphis marsupialis virginiana , Kerr, was made to determine the pattern of hand muscle innervation in a relatively primitive quadruped mammal. Four pairs of preserved opossum hands were dissected, and the innervation of their muscles studied with a stereobinocular microscope. The distributions of the median and ulnar nerves to the hand muscles are outlined, and the details of distribution are illustrated by means of seven diagrams. Peculiar anastomoses were consistently found between the superficial interdigital rami of the median nerve and branches of the deep volar ramus of the ulnar nerve, and the short deep flexors of digit II consistently received all, or a part, of their innervation from superficial interdigital rami of the median nerve. Five features of these unusual nerve connections and distributions are summarized and discussed.