The superior laryngeal nerve is an important anatomical structure when thyroid surgery is performed.
It is a branch of the vagus nerve and itself branches into a larger, internal branch which is sensory and an external branch which is motor. It passes through the cricothyroid membrane medially.
The superior laryngeal nerve is most often damaged during thyroid surgery when the superior pole vessels of the thyroid are divided too cephalad. Injury to the external motor branch results in loss of voice strength and quality, but not hoarseness as sometimes thought.