A CADAVERIC STUDY OF HEAD AND NECK NEUROVASCULAR ANATOMICAL VARIATIONS

This study reports the incidence of head and neck neurovascular branching variations. While there is an extensive literature on the incidence of many anatomical variations because of their relevance to surgical cases, the incidence of some variations are still unknown. In addition, whether the incidence of variations differs between samples is under-explored. We therefore set out to determine whether incidence of neurovascular branching variations in a cadaveric sample in north Texas match previously reported findings, and also to document variations in the location of the vagus nerve, which has not been reported previously. Purpose (a): While anatomical variations have long been documented because of their surgical relevance, some remain unknown. In addition, between-sample differences in the incidence of variations is under-explored. We tested whether incidence of head and neck neurovascular branching variations in a cadaveric sample from UNTHSC match previous findings. We also document previously unreported positional variations for the vagus nerve. Methods (b): First-year students from the Texas College of Osteopathic Medicine recorded neurovascular variations using a standardized data sheet during their dissections. Cadavers in this study (n=29) were donated through the University of North Texas Health Science Center Willed Body Program. Results (c): The ascending pharyngeal artery branched from the external carotid artery (ECA) in 74% of cases, from the common carotid artery (CCA) in 11%. The lingual artery branched from the ECA in 82% of cases; 6% shared a common trunk with the facial artery. The vagus nerve was located between the CCA and internal jugular vein in 62% of cases, posterior to the internal jugular vein in 24%, and anterior to the CCA in 4%. Conclusions (d): Incidence of arterial branching variations mostly fell within previously reported ranges (Bergman, 1996). Differences with previous work are attributable to the small sample size of this study, which emphasizes the need for large samples when estimating the frequency of a variation. We also report information on positional variation of the vagus nerve. These data must be treated with caution due to possible inter-observer error, but further investigation of vagus nerve positional variation is warranted due to implications for patient safety.