General Medical Information

Hypopharynx

Susan D. John
Michael D. Maves

The laryngeal part of the pharynx, or hypopharynx, extends from just above the level of the hyoid bone superiorly to the lower border of the cricoid cartilage inferiorly, narrowing rapidly to become continuous with the esophagus. The anterior wall is formed laterally by mucosa on the medial surface of the thyroid cartilage and centrally or medially by the larynx and its appendages. Above is the epiglottis and the aditus of the larynx. Below the aditus, the anterior wall of the pharynx is also the posterior wall of the larynx. Lateral to the epiglottis are the lateral glossoepiglottic folds that form the anterolateral boundary between the oral and laryngeal parts of the pharynx. Below these folds, the hypopharynx extends forward around the sides of the larynx between this area and the thyroid cartilage. These bilateral expansions are the piriform recesses or sinuses.

The intrinsic portion of the larynx consists of the epiglottis, false vocal folds, laryngeal ventricles, paired true vocal folds, and arytenoid cartilages in the posterior aspect. Contained within the aryepiglottic folds are the paired corniculate and cuneiform cartilages. The space between the two vocal folds is the glottis.

The muscles of the pharynx are the superior, middle, and inferior constrictors. These muscles look like ice cream cones inserted into one another. They gradually merge to form the cricopharyngeus muscle at its inferior extent and then the esophagus. Each constrictor inserts with the corresponding muscle of the opposite side and the midline into a posterior midline raphe. These muscles are innervated by cranial nerve X through the pharyngeal plexus. Dehiscence in the pharyngeal constrictors may give rise to Zenker diverticula. Immediately lateral to the pharyngeal muscles are the great vessels of the neck and cranial nerve X.