Surgical Anatomy of the Medial Antebrachial Cutaneous Nerve: Clinical Application in Ulnar Nerve Decompression Surgery in the Elbow

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 -18mm. 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.