Abstract
Introduction Lesion to the posterior branch of the medial antebrachial cutaneous nerve (MACN)
is one of the causes of revision of the ulnar nerve decompression surgery in the elbow.
To avoid the morbidity associated with this injury, cadaver dissections were performed
to identify this branch in its course through the ulnar tunnel.
Methods We included 20 upper extremities of fresh cadaveric specimens. The posterior branch
of the MACN was identified proximal to medial epicondyle and followed past the ulnar
tunnel. The number of ramifications and their coordinates were recorded in a Cartesian
plane, with the medial epicondyle as the central point.
Results The posterior branch passed proximal and posterior to the medial epicondyle in all
specimens, except one. The average of the adjusted x value is of 30 mm, and of the adjusted y value is -18 mm. Additionally, we determined that the posterior branch passes at
an average angle of 30° with respect to the x axis.
Conclusion The anatomical descriptions of this branch focused on surgical release of the ulnar
nerve in the elbow are limited, and measures are only described in the horizontal
plane (from proximal to distal). Schematizing the anatomy of this branch in its course
throughout the ulnar tunnel will facilitate its identification during the procedures.
However, variability and asymmetry in the branching pattern should be considered.
Keywords anatomy - ulnar tunnel syndrome - peripheral nerve injury
