The piriform fossa or recessus piriformis in Latin (‘pyriformis’ meaning pear-shaped) is a depression present on either side of the laryngeal orifice. It is located in the hypopharyngeal region of the pharynx, between the hyoid bone and the lower border of the cricoid cartilage. Its base lies superiorly, while its apex points downwards. And it consists of two parts: a shallow upper region and a deep lower one.
It is bounded laterally by the mucosa covering the thyroid cartilage lamina, and medially by the aryepiglottic fold of the larynx, the arytenoid cartilages, and the cricoid cartilage. Superiorly, it is bounded by the glossoepilglottic fold, and is continuous with the esophagus inferiorly.
The recurrent laryngeal nerve and the internal laryngeal nerve, a branch of the superior laryngeal nerve arising from the vagus, lie deep to the mucous membrane of the piriform fossa. The latter nerve provides sensation to this area, and can be damaged if the mucous membrane was punctured one way or another.
The piriform fossa is a common site for food to be trapped when not swallowed properly. Foreign material can be lodged in the fossa during infancy as well. The sensation of food being stuck can be felt when this area is injured.
The piriform fossa is a subsite of the hypopharynx (or laryngopharynx). It is the most common site for cancers in that region. Tumors involving the pyriform fossa commonly originate from its deep portion that is not visible through indirect laryngoscopy, hence it can go by undetected without a direct examination involving the esophageal speculum.
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