Laryngopharynx

Pars laryngea pharyngis

Also known as: hypopharynx, piriform fossa, piriform recess

The lowest part of the pharynx, behind the larynx, from the upper border of the epiglottis to the lower border of the cricoid cartilage (C6), where it continues as the oesophagus.

Overview

The laryngopharynx lies opposite C4–C6. Its anterior wall contains the laryngeal inlet (bounded by the epiglottis, aryepiglottic folds and arytenoids) and, below it, the posterior surfaces of the arytenoid and cricoid cartilages (post-cricoid region). On each side of the inlet is a piriform fossa (recess), a gutter bounded medially by the aryepiglottic fold and laterally by the thyroid lamina, which channels food and fluid around the closed larynx into the oesophagus.

The internal laryngeal nerve and superior laryngeal vessels run just beneath the mucosa of the piriform fossa. The inferior constrictor forms the back wall; between its oblique thyropharyngeus and horizontal cricopharyngeus fibres is a weak area, Killian's dehiscence.

Location

Posterior to the larynx, from the upper border of the epiglottis to the lower border of the cricoid (C4–C6).

Parts & subdivisions

Piriform fossae

Lateral food channels beside the laryngeal inlet; internal laryngeal nerve beneath the mucosa.

Post-cricoid region

Mucosa behind the cricoid lamina, leading to the oesophagus.

Cricopharyngeus

Lowest part of the inferior constrictor; functional upper oesophageal sphincter, relaxing during swallowing.

Anatomy

Innervation

Sensory: internal laryngeal nerve (CN X) and recurrent laryngeal nerve. Motor: vagus via pharyngeal plexus; cricopharyngeus also receives recurrent laryngeal fibres.

Arterial supply

Superior and inferior thyroid arteries (laryngeal branches); ascending pharyngeal artery.

Lymphatic drainage

Deep cervical, paratracheal and retropharyngeal lymph nodes.

Clinical significance

Foreign bodies and nerve block

Fish bones commonly lodge in the piriform fossae or valleculae; perforation or removal can injure the internal laryngeal nerve, abolishing sensation above the vocal folds and the protective cough reflex. The nerve can be anaesthetised here for awake laryngoscopy.

Hypopharyngeal carcinoma and Plummer–Vinson syndrome

Squamous carcinoma arises most often in the piriform fossa and presents late (dysphagia, otalgia, neck mass). Plummer–Vinson syndrome (iron-deficiency anaemia, post-cricoid web, dysphagia) predisposes to post-cricoid carcinoma.