A Cadaveric Study of Anatomical Variations in Neurovascular Branching Patterns of the Head and Neck

At approximately the level of the fourth cervical vertebra (C4), the common carotid artery (CCA) bifurcates into the internal carotid artery (ICA) and the external carotid artery (ECA) to supply the brain and facial structures, respectively. The purpose of this study is to examine anatomical variations in the origin and order of the left and right sides of the ascending pharyngeal artery, lingual artery, and thyrocervical trunk, which branch off the ECA, as well as the location of the vagus nerve within the carotid sheath with respect to neighboring vessels. Possible differences between left and right sides as well as males and females for these vessels were examined. This study includes data from cadavers (n = 63) made available through the University of North Texas Health Science Center (UNTHSC) Willed Body Program. Variations were documented through responses to a data sheet with multiple-choice questions; side and sex differences were evaluated using chi-square tests in SPSS. Significant differences between left and right sides for all vessel branching patterns were detected (X2 ≥ 25.9, df = 1, p ≤ 0). In addition, differences were found between males and females in the left ascending pharyngeal artery (X2 = 9.8, df = 1, p = 0.022), right thyrocervical trunk (X2 = 14.483, df = 1, p = 0.017), and left vagus nerve (X2 = 26.773, df = 1, p = 0.007). From this study it may be concluded that significant branching variations of the ECA exist. This information opens up questions such as whether or not there are evolutionary advantages to specific anatomical variations such as if certain branching patterns provide better blood flow to specific regions, or if there are physiological advantages associated with different locations of the vagus nerve. From a surgical standpoint, further study of anatomical variations can provide better insight as to whether there are complications that can be associated with particular branching patterns, or if certain vessels are more susceptible to damage from spontaneous vascular injury (e.g., stroke, aneurysm).