Ulnar Nerve, Its Termination and Superficial Branches in Hand: A Cadaveric Study

Abstract

Nerves supplying the hand are notoriously variable in their divisions and their course; do not follow any standard pattern. The palmar aspect of hand is supplied by median and ulnar nerve. The clinical importance of Guyon's canal is emphasized due to the various branching patterns of the ulnar nerve in this canal. The palmar aspect of hand is usually supplied by ulnar nerve and median nerve. Medial one and a half fingers are supplied by ulnar nerve and lateral three and a half fingers are supplied by the median nerve. The branches of ulnar nerve are notoriously variable morphologically and no standard pattern can be given regarding the course of these branches. Presence of trifurcation of ulnar nerve or communications of superficial branches to median nerve do not cause symptoms usually but becomes important during surgical and orthopaedic interventions. Material and Methods: The study was conducted on 40 hands (20 left and 20 right) of preserved adult human cadavers.The roof of the Guyon's canal was opened with care not to disturb the stuctures. The ulnar nerve observed for its terminal branches, the course of its superficial branches was observed. The point of division of superficial branch into digital branches was measured from bistyloid line. The point of origin of superficial communicating branch from superficial branch or digital branch of ulnar nerve to median nerve was observed from bistyloid line. Observations: In 29 hands the ulnar nerve showed bifurcation, in 10 hands it trifurcated in the Guyon's canal and in 1 right hand of a male cadaver there was higher division of the ulnar nerve and trifurcation.The superficial branch was observed for its course and division from bistyloid line. The superficial branch gave rise to 2 digital branches in 27 hands and it gave 3 branches i.e. 2 digital branches and 1 communicating branch to medialmost digital branch of median nerve in 13 hands. The typical ramus communicans from digital branch of ulnar nerve to the medial most digital branch of median nerve was observed in 27 hands.(67.5%). Conclusion: This study attempted at exploring the superficial anatomy of ulnar nerve in hand.The branching pattern of the ulnar nerve in Guyon's canal is variable as there is no exact level at which the nerve terminates.The superficial communicating branch to median nerve though present in all the hands but the typical ramus communicans was observed in 67.5% of specimens. Thus surgical procedures in hand should be planned carefully keeping in mind in advance such variations which can be encountered.

Anatomical Study on the Branching Pattern of the Ulnar Nerve in the Wrist and Palm

“…13 The superficial terminal branch divided into 2 digital (1 common and 1 proper) branches in 67.5% of specimens and into 3 branches (2 digital and 1 communicating branch) in 32.5% specimens. 10 In the present study, in 28/40 specimens superficial terminal branch divided into medial proper and common digital branches. In 12/40 specimens, the nerve divided into proper, common digital branches and a communicating nerve to digital branch of median nerve.…”

“…9 According to Priyadarshini et al, in 29 out of 40 (72%) of the specimens the ulnar nerve bifurcated, in 10(25%) specimens, the ulnar nerve trifurcated in the Guyon's canal and in 1 (2.5%)specimen there was higher division of ulnar nerve and trifurcation. 10 In 2010, Nitasu M et al, studied the variations of ulnar nerve in Guyon's canal using ultrasound and 3T MRI. In 21/30 hands (70%) hands, ulnar nerve bifurcated and in the rest it trifurcated.…”