Anomalous artery directly connecting the external and internal carotid arteries

An anomalous artery directly connecting the external with the internal caro tid artery was encountered on the right side of a 68-year-old Japanese fema le cadaver. This anomalous artery (5 mm in diameter, 12 mm in length) branc hed out from the posterior aspect of the external carotid at the level of t he origin of the lingual artery, ran obliquely upward posteriorly along the course of the hypoglossal nerve, and was confluent with the anterior aspec t of the internal carotid artery No other variations were found in the morp hological aspects of, or in the anatomical relationships between, the carot id arteries and their surrounding structures on either side. The carotid bo dy-like structure was observed at the carotid bifurcation and was innervate d by small branches of the glossopharyngeal, the vagus and the sympathetic trunk. Embryologically, it is conceivable that this anomalous artery may ha ve derived from the right second branchial arch artery, although there is n o abnormality in other derivative structures of the second pharyngeal arch. There may have been no effect from this anomaly on the functions of the ar terial blood flow and blood supply under normal circumstances in the presen t case, but this report may be of embryological significance and contribute some insight into the mechanisms of the formation of the carotid circulati on systems.