The external laryngeal branch of the vagus is in contact with its upper pole and with the superior thyroid artery in the angle between the attachments of the Inferior Constrictor and Sterno-thyroid. The recurrent branch of the vagus is a medial relation as far as the lower border of the Inferior Constrictor, ie, up to the level of the cricoid cartilage.
Boileau Grant JC. 5th ed. Baltimore. Md: Williams & Wilkins Co; 1952:684.
March 2004. Arch Surg. 2004;139(3):298. doi:10.1001/archsurg.139.3.298