Anatomic sites of origin of the suprascapular and lateral pectoral nerves within the brachial plexus.

BACKGROUND: The goal of this study was to clarify the anatomical origins of the suprascapular and lateral pectoral nerves from the brachial plexus as an aid to surgical exploration.

METHODS: Both nerves were studied in 100 adult cadaver specimens. Topographic points of origin were described as distance from the bifurcation of the upper trunk or distance from the formation point of the lateral cord, using visual anatomical models.

RESULTS: The suprascapular nerve originated from (1) the posterior division of the upper trunk distal to the bifurcation of the upper trunk (61 specimens); (2) the point of upper trunk bifurcation (29 cases); (3) the upper trunk proximal to the bifurcation point (six cases); and (4) directly from the C5 root (four cases). The lateral pectoral nerve originated from (1) the anterior division of the upper trunk proximal to the point of lateral cord formation (88 cases); (2) the point of lateral cord formation (five cases); (3) the lateral cord distal to the lateral cord formation point (four cases); and (4) the anterior division of the middle trunk (three cases). Eighty-two cases had origins from both the anterior upper trunk and the anterior middle trunk.

CONCLUSIONS: The suprascapular nerve most frequently originates from the posterior division of the upper trunk, and the lateral pectoral nerve from the anterior divisions of the upper and middle trunks. This information can be used to guide the surgeon in identifying the key landmarks of the supraclavicular brachial plexus at surgical exploration.