Origin of suprascapular and lateral pectoral nerves from the brachial plexus: surgical vs anatomical findings

Abstract

Most frequently the suprascapular nerve (SSN) is described as originating from the superior trunk (ST), and the lateral pectoral nerve (LPN) from the lateral cord (LC). However, during brachial plexus (BP) neurotization surgery the SSN and LPN are commonly observed to originate from the divisions. The purpose of this study is to define the origin of SSN and LPN. The BP was exposed with 3.5× loupe magnification, as used during surgery, in 10 Thiel and 20 formalin‐embalmed specimens. The origins of the SSN and LPN were documented; the BP was digitized and the data modeled in Autodesk MAYA®. The models were used to visualize and quantify the origins of SSN and LPN. The SSN originated from: (1) posterior division of ST 63.4%; (2) point of bifurcation of ST into divisions 23.3%; (3) C5 root 13.3%. Distance from the origin of SSN to bifurcation of ST ranges from 0 – 16mm. All 30 LPNs originated proximal to the LC, arising from: (1) middle trunk (MT) and anterior division of ST 86.6%; (2) anterior division of ST 13.3%; (3) MT 3.4%. Distance from the origin of LPN to the formation of LC ranges from 6 – 43mm. As observed in surgery, the origin of the SSN is more distal than defined in the literature, and the LPN more proximal. This may be due to maintenance of epineural integrity during surgery but not in traditional studies where nerves may appear to originate more distally or proximally. Renewed study of BP with attention to epineural integrity is needed.