The Trifurcated Anatomy of The Upper Trunk of The Brachial Plexus: Suprascapular Nerve, Posterior Division, and Anterior Division.

OBJECTIVE

To provide a comprehensive depiction of the anatomy of the upper trunk and its distal trifurcation through the dissection of brachial plexuses obtained from adult cadavers.

METHODS

We dissected 40 brachial plexuses from adult cadavers preserved using a unique formalin-based technique developed and used by the Anatomy Department of our institution. Bilateral dissection was performed on 20 cadavers placed in the dorsal decubitus position with accurate arm adduction. While the primary focus was on the upper trunk's anatomy, a thorough exploration of the entire brachial plexus was achieved through an extended incision.

RESULTS

The posterior division of the upper trunk was consistently located between the suprascapular nerve and the anterior division. In 22 (55%) of the dissected brachial plexuses, the suprascapular nerve originated from the proximal region of the posterior division of the upper trunk, immediately after its bifurcation. For the remaining 18 (45%), the suprascapular nerve originated directly from the upper trunk.

CONCLUSION

The distal trifurcation of the upper trunk of the brachial plexus includes the suprascapular nerve and the posterior and anterior divisions of the upper trunk.