Laryngopharynx

The laryngopharynx (a.k.a. hypopharynx) is the inferior part of the pharynx located posterior to the larynx. It serves as a common pathway for both air and food and extends from the upper border of the epiglottis to the lower border of the cricoid cartilage, where it continues as the oesophagus.

Boundaries

Important features

1. Piriform fossae (piriform recesses)

• These are mucosal depressions on either side of the laryngeal inlet. They channel food around the laryngeal opening during swallowing.

• Common site for lodgement of fish bones and foreign bodies, and for hypopharyngeal carcinoma.

2. Laryngeal inlet

Bounded by:

• Epiglottis anteriorly.

• Aryepiglottic folds laterally.

• Inter-arytenoid fold posteriorly.

3. Muscles

The wall is formed mainly by the inferior pharyngeal constrictor, which consists of:

• Thyropharyngeus

• Cricopharyngeus

The cricopharyngeus acts as the upper oesophageal sphincter.

Blood supply and lymphatics

• Arterial supply - Superior and inferior thyroid arteries, and ascending pharyngeal artery

• Venous drainage - Pharyngeal venous plexus, which drains into the internal jugular vein

• Lymphatic drainage - Deep cervical lymph nodes, which drain into the jugulodigastric and jugulo-omohyoid nodes.

Innervation

1. Motor

Via the pharyngeal plexus - Vagus nerve (CN X) supplies most muscles.

2. Sensory

• Internal laryngeal nerve (branch of CN X).

• Glossopharyngeal nerve (CN IX) contributes superiorly.

Clinical Correlates

• Foreign bodies, such as, fish bones commonly lodge in the piriform fossae and may injure the internal laryngeal nerve, causing reduced sensation above the vocal folds.

• Hypopharyngeal carcinoma frequently arises in the piriform recess.

• Zenker's diverticulum can occur due to herniation of pharyngeal mucosa through Killian's dehiscence between the thyropharyngeus and cricopharyngeus parts of the inferior constrictor muscle, causing dysphagia, regurgitation, and halitosis.

• Cricopharyngeal dysfunction due to failure of relaxation of the upper oesophageal sphincter can result in dysphagia.