The pyriform sinus (also spelled piriform sinus and also known as the pyriform recess, pyriform fossa, and smuggler's fossa) is the pear-shaped subsite of the hypopharynx located posterolaterally to either side of the laryngeal opening.
Relations and/or boundaries
The structure is a depression bounded
- medially by the aryepiglottic fold and arytenoid and cricoid cartilages
- laterally by the thyroid cartilage and thyrohyoid membrane
- superiorly by the level of the hyoid bone
- inferiorly by the level of the inferior border of the cricoid cartilage
Beneath the mucous membrane of the anterior wall runs the internal laryngeal nerve, a branch of the superior laryngeal nerve.
The term is derived from the Latin "pirum" and -form, meaning having the form of a pear.