Compression of the Deep Palmar Branch of the Ulnar Nerve

A case of compression of the deep branch of the ulnar nerve is described. 2. Anatomical evidence is presented that the reason for the special liability of the deep branch to be compressed by ganglia in this region is its relationship to a ligamentous band which passes from the pisiform bone to the hamate superficial to the deep branch of the ulnar nerve. 3. This band, though constant, has not been well recognised.