[The external laryngeal nerve].
An investigation on the external laryngeal nerve is carried out from cadeverous material (24 thyroid glands). Various origins of the nerve are reported. The relationships are investigated. They are particularly important on the superior pole of the thyroid gland. The nerve may pass at a variable distance of the superior pole of the thyroid gland. The size of the gland and particularly the more the more or less early intramuscular course of the nerve through the fibers of the inferior pharyngeal constrictor muscle determine the relationships. Those relationships will be made closer if the nerve is adherent to the thyroid sheath, passes forward of the superior thyroid artery or between the supra polar branches. The collateral nervous branches for the thyroid gland or for the thyroid vessels, the arterial branches which passed into the pharyngeal constrictor muscle with the nerve may also change the relationships. Practical applications in thyroid surgery are made through this investigation.