label: Branchial sinus
label_lc: branchial sinus
description: "A congenital branchial sinus is a remnant of the embryonic branchial arches and their intervening clefts and pouches that has failed to regress completely. Sinuses typically have their external orifice inferior to the ramus of the mandible. They may traverse the parotid gland, and run in close vicinity to the facial nerve in the external auditory canal."