Descendens vagohypoglossi: rare variant of the superior root of ansa cervicalis.

Knowledge of variants in the formation and position of the ansa cervicalis is important in head and neck surgery, specifically in reconstructions of the tongue that use the infrahyoid muscles, and in the anastomosis of the ansa cervicalis to the recurrent laryngeal nerve when the laryngeal muscles have been paralysed. We describe a rare variant of the superior root of the ansa cervicalis, which had a contribution from the vagus and hypoglossal nerves. The inferior root was formed by the C2 and C3 ventral rami, but it passed medial to the internal jugular vein before it joined the superior root to form the loop.