A Variant Origin of the Carotid Sinus Nerve.

The carotid sinus nerve is known to convey baroreceptive fibers from the carotid sinus. Despite studies on the baroreflex pathway and the course and communications of the carotid sinus nerve with the surrounding nervous and vascular structures, there have been scant reports on variations in the origin of the carotid sinus nerve (CSN). We identified an unusual origin of the CSN. On the right side of a cadaveric specimen, the CSN was found to arise from two small rami extending from the external laryngeal nerve. Such a case can help better understand various pathways used to monitor the carotid sinus. Additionally, surgeries that manipulate the superior laryngeal nerve could possibly injure a variant carotid sinus nerve, as seen in the present case.