Superior laryngeal nerve

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Course, branches and nuclei of the vagus nerve.

The superior laryngeal nerve is a branch of the vagus nerve, arising from its inferior ganglion. It also receives some sympathetic branches from the superior cervical ganglion. Within the carotid sheath at approximately the level of the hyoid bone, the superior laryngeal nerve divides into the internal and external laryngeal nerves. 

The internal laryngeal nerve descends down to the thyrohyoid membrane and pierces it, entering the larynx alongside the superior laryngeal artery. It provides sensory innervation to most of the laryngeal mucosa above the vocal folds.

The external laryngeal nerve, which is smaller than the internal branch, pierces and supplies the inferior pharyngeal constrictor on its way down to supply the cricothyroid muscle, the only intrinsic laryngeal muscle not supplied by the recurrent laryngeal nerve. The external laryngeal nerve also gives branches to the pharyngeal plexus.