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Background: The branching pattern of vessels emerging from the external carotid artery varies considerably. Knowledge of this variation is critical for clinicians who perform neck procedures. This study assessed the origin of the four primary caudal branches of the external carotid artery (superior thyroid, lingual, facial, and occipital arteries) with regard to sex and side. The position of common carotid artery bifurcation was also analyzed with regard to sex and side.

 Methods: The carotid arterial system of 79 cadavers from the eastern United States (37 male, 42 female) was dissected bilaterally. The position of carotid bifurcation relative to a midpoint between the suprasternal notch and mastoid process was measured with digital fractional calipers. Origin of the caudal branches was determined and the distance from the carotid bifurcation measured.

 Results: On the right, the superior thyroid artery emerged from the carotid bifurcation/external carotid more frequently than it did from the common carotid (67% and 31%, respectively); however, on the left, it emerged more frequently from the common carotid (57% and 43%, respectively) (p = 0.003). No side-dependent differences were observed for the remaining three caudal branches. The occipital artery emerged below the origin of the facial artery more frequently than at/above (55% and 44%, respectively). No significant differences were found for the origin of the caudal four branches with regard to sex. There was no significant difference in the location of the carotid bifurcation with regard to sex or side.

Conclusions: The origin of the superior thyroid artery differed when comparing neck side, while the origin of the occipital artery frequently emerged caudal to that of the facial artery. Both findings are inconsistent with most anatomical atlases. The positions of the carotid bifurcation as well as the origin of the remaining caudal branches were no different with regard to either parameter.