A cadaveric study of the distribution pattern of the cutaneous sensory fibres of the distal palm of the hand

The Cutaneous Branches of the Median and Ulnar Nerves in the Palm

PURPOSE

The dermatomal distributions of the ulnar and median nerves on the palmar skin of the hand have been studied thoroughly. However, the anatomic course of the median and ulnar cutaneous nerve branches and how they supply the skin of the palm is not well understood.

METHODS

The cutaneous branches of the median and ulnar nerves were dissected bilaterally in 9 fresh cadavers injected arterially with green latex.

RESULTS

We observed 3 groups of cutaneous nerve branches in the palm of the hand: a proximal row group consisting of long branches that originated proximal to the superficial palmar arch and reached the distal palm, first web space, or hypothenar region; a distal row group consisting of branches originating between the superficial palmar arch and the transverse fibers of the palmar aponeurosis (these nerves had a longitudinal trajectory and were shorter than the branches originating proximal to the palmar arch); and a metacarpophalangeal group, composed of short perpendicular branches originating on the palmar surface of the proper palmar digital nerves at the web space. The radial and ulnar borders of the hand distal to the palmar arch were innervated by short transverse branches arising from the proper digital nerves of the index and little finger. Nerve branches did not perforate the palmar aponeurosis in 16 of 18 cases.

CONCLUSIONS

The palm of the hand was consistently innervated by 20-35 mm long cutaneous branches originating proximal to the palmar arch and shorter branches originating distal to the palmar arch. These distal branches were either perpendicular or parallel to the proper palmar digital nerves.

CLINICAL RELEVANCE

Transfer of long proximal row branches may present an opportunity to restore sensibility in nerve injuries.

Nerve Diameter in the Hand: A Cadaveric Study

Background

Nerve injuries in the hand are common and often pose a challenge for the upper extremity surgeon. A range of reconstructive options exist for nerve repair, but proper matching of nerve diameter is important for many of these techniques. The purposes of this study were to (1) describe the nerve diameters of the hand and their relative differences and (2) investigate whether there is a relationship between nerve diameter and external hand dimensions or body mass index.

Methods

We utilized 18 freshly frozen cadaveric hands from adult donors aged 20-86 of both sexes for this study. Two independent observers measured each nerve diameter to the nearest 0.1 mm using a digital caliper.

Results

Using the flexor zones as boundaries, a total of 33 nerve measurements were performed for each cadaveric hand. Nerve diameter increased from the distal to the proximal flexor zones. The internal common digital nerves in flexor zone 3 were larger than the external digital nerves. The median nerve was found to be nearly 2 times larger than the ulnar nerve at 2 locations within the wrist. There was a positive correlation between body mass index, hand span, hand width, and nerve diameter at several measured locations.

Conclusions

This study provides reference values for nerve diameters of the hand and wrist and describes their relative differences. It is important for surgeons to be aware of these differences and to consider this information as we advance our efforts to reconstruct the hand and develop technologies for nerve repair.