ANNALS OF ANATOMY An unusual termination of the ulnar nerve in the palm M. C. Bozkurt, E. Cezayirli*, and S. M. Tagil* University of Kirikkale, Faculty of Medicine, Department of Anatomy, Kirikkale, Turkey, and *University of Ankara, Faculty of Medicine, Department of Anatomy, Ankara, Turkey Summary. During the dissection of the left forealm and hand of a 57-year old male cadaver fixed in 10% forma- lin, it has been noted that the medial proper palmar digi- tal nerve to the little finger arose from the dorsal branch of the ulnar nerve, instead of the superficial branch of the same nerve. The dorsal branch, given off by the ulnar nerve in the forearm, coursed distally and dorsally deep to the flexor carpi ulnaris muscle. Some 2 cm proximal to the pisiform, it pierced the deep fascia on the posteromedial side of the muscle to become superficial. At this point, one of the three branches given off travelled distally on the pal- mar-ulnar side of the hand to the skin of the little finger. There were connections between this branch and the branches of the superficial branch of the ulnar nerve which innervated the skin of the hypothenar eminence. Further, another branch of the superficial branch of the ulnar nerve passed under the fibrous arch of the flexor di- gift minimi brevis muscle origin and the opponens digiti minimi muscle to re-unite with its parent nerve. Key words: Ulnar nerve - Variation - Hand taining the relationship held in the forearm. It courses medial to the ulnar artery and radial to the pisiform, where it is covered by proximal parts of the palmaris bre- vis muscle (Gross and Gelberman 1985). The ulnar nerve trunk has classically been described as dividing into superficial sensory and deep motor branches. The superfi- cial branch gives off a motor branch to the palmaris bre- vis muscle, a medial branch which forms the medial proper palmar digital nerve to the little finger and a lat- eral branch, the common palmar digital nerve to the fourth interosseous space. The common palmar digital nerve then divides into two terminal branches to form the radial proper palmar digital nerve to the little finger and the medial proper palmar digital nerve to the ring finger. The deep terminal branch of the ulnar nerve passes through the Guyon's canal with branches supplying the hypothenar muscles. As it crosses the deep palm, it sup- plies the palmar and dorsal interossei, the third and fourth lumbricals, the adductor pollicis and the deep part of the flexor pollicis brevis (Williams et al. 1995; Bonnel and Vila 1985). Introduction The ulnar nerve passes through a fibroosseous tunnel known as Guyon's canal or the distal ulnar tunnel and di- vides into its two terminal branches at the wrist. It enters the tunnel dorsal to the palmar carpal ligament and pal- mar to the flexor retinaculum and the flexor digitorum tendons. The nerve lies medial to the ulnar artery main- Correspondence to: M. Cem Bozkurt, Ata Sokak 10/10, Anittepe, Ankara 06580, Turkey Findings An unusual branching and course of the ulnar nerve in the left forearm and hand was found in the dissection of a 57 year old male cadaver fixed in 10% formaldehyde solution. The medial proper palmar digital nerve to the little finger arose from the dorsal branch of the ulnar nerve instead of the superficial branch (Fig. 1). The dor- sal branch of the ulnar nerve arose from the ulnar nerve 4.8 cm proximal to the proximal edge of the pisiform, then continued distally and dorsally deep to the flexor carpi ulnaris muscle. After it emerged at the dorsomedial border of the flexor carpi ulnaris muscle, it pierced the Ann Anat (2002) 184:271-273 © Urban & FischerVerlag http:llwww, urbanfischer.deljournalslannanat 0940-9602/02/184/3-271 $15.00•0