Innervation of the lumbrical muscles.

It has long been recognized that the first and second lumbricals are normally innervated by the median nerve, whereas the third and fourth lumbricals are innervated by the ulnar nerve (Sunderland and Ray, 1946). However, the courses of the motor nerves, particularly to the first two lumbricals and their loci of insertion, have not been clearly described. Because this information may be useful to a surgeon operating in the palm, we undertook a cadaver study to define more precisely the pathways of innervation of the lumbrical muscles.