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Clinically-relevant variations of the carotid arterial system.

INTRODUCTION
Developmental anomalies in the origin and branching pattern of the external carotid artery are not common. The level of the bifurcation of the common carotid artery and also the variations in the origin/branching pattern of the external carotid artery are well known and documented.


METHODS
The variations in the level of bifurcation of the common carotid artery and the branching pattern of the external carotid artery were studied on 95 cadavers (52 male and 43 female). The common, external and internal carotid arteries were dissected on both sides. The level of carotid bifurcation was determined by comparison with the cervical vertebrae. Branching patterns of the carotid arteries were examined.


RESULTS
Apart from the textbook description of the arteries, we came across several interesting variations. The bifurcation level of the common carotid artery was determined to be 50 percent at the C3 level, 40 percent at the C4 level and ten percent at the C2 level on the right side, and 55 percent at the C3 level, 35 percent at the C4 level, one percent at the C5 level and nine percent at the C2 level on the left side.


CONCLUSION
Anatomical knowledge of the origin, course, and branching pattern of the external carotid artery, as well as the level of bifurcation of the common carotid artery, will be useful to surgeons when ligating the vessels in the head and neck regions during surgery and to avoid unnecessary complications during carotid endarterectomy.