The internal laryngeal nerve is the internal branch (ramus internus) of the superior laryngeal nerve

Superior laryngeal nerve

The superior laryngeal nerve is a branch of the vagus nerve. It arises from the middle of the ganglion nodosum and in its course receives a branch from the superior cervical ganglion of the sympathetic....

. It descends to the thyrohyoid membrane, pierces it in company with the superior laryngeal artery

Superior laryngeal artery

The superior laryngeal artery accompanies the internal laryngeal branch of the superior laryngeal nerve, beneath the Thyreohyoideus.This artery branches from the superior thyroid artery near its bifurcation from the external carotid artery...

, and is distributed to the mucous membrane

Mucous membrane

The mucous membranes are linings of mostly endodermal origin, covered in epithelium, which are involved in absorption and secretion. They line cavities that are exposed to the external environment and internal organs...

 of the larynx

Larynx

The larynx , commonly called the voice box, is an organ in the neck of amphibians, reptiles and mammals involved in breathing, sound production, and protecting the trachea against food aspiration. It manipulates pitch and volume...

.

Of these (sensory) branches some are distributed to the epiglottis

Epiglottis

The epiglottis is a flap that is made of elastic cartilage tissue covered with a mucous membrane, attached to the entrance of the larynx. It projects obliquely upwards behind the tongue and the hyoid bone, pointing dorsally. The term, like tonsils, is often incorrectly used to refer to the uvula...

, the base of the tongue

Tongue

The tongue is a muscular hydrostat on the floors of the mouths of most vertebrates which manipulates food for mastication. It is the primary organ of taste , as much of the upper surface of the tongue is covered in papillae and taste buds. It is sensitive and kept moist by saliva, and is richly...

, and the epiglottic glands; others pass backward, in the aryepiglottic fold

Aryepiglottic fold

The entrance of the larynx is a triangular opening, narrow in front, wide behind, and sloping obliquely downward and backward. It is bound, in front, by the epiglottis; behind, by the apices of the arytenoid cartilages, the corniculate cartilages, and the interarytenoid notch; and on either side,...

, to supply the mucous membrane surrounding the entrance of the larynx, and that lining the cavity of the larynx as low down as the vocal folds.

A filament descends beneath the mucous membrane on the inner surface of the thyroid cartilage

Thyroid cartilage

The thyroid cartilage is the largest of the nine cartilages that make up the laryngeal skeleton, the cartilage structure in and around the trachea that contains the larynx....

 and joins the recurrent nerve.

Above the vocal folds the sensory innervation of the larynx is via the internal laryngeal nerve. Below the vocal folds it is by way of branches of the recurrent laryngeal nerve

Recurrent laryngeal nerve

The recurrent laryngeal nerve is a branch of the vagus nerve that supplies motor function and sensation to the larynx . It travels within the endoneurium...

. The vocal fold itself receives dual innervation from both nerves.

Pathology

Irritation of the internal laryngeal nerve results in uncontrolled coughing - usually as a result of food or water in the laryngopharynx.