Editing Thyroid (section)

=== '''External branch of superior laryngeal nerve''' ===

** Anatomy
*** SLNs branch off vagus at the level of hyoid bone and run along the inferior pharyngeal constrictor, before running parallel to the upper aspect of the superior pole thyroid vessels and then terminating in the cricothyroid muscle
*** EBSLN typically runs fairly high above the thyroid lobe
*** Take care when ligating and dividing the superior pole vessels - can sometimes run quite close to the vessels and the upper thyroid lobe, and sometimes need to dissect it away
*** Cernea classification below
** Function
*** Larynx - cricothyroid muscles, and contributes to vocal fold tone and tension
** Injury
*** Paresis of ipsilateral cricothyroid, leading to inability to tighten ipsilateral cord
*** Difficulty achieving high pitch and vocal projection and volume
**