Pharyngoesophageal constriction
Constrictio pharyngooesophagea
- Latin synonym: Constrictio pharyngooesophagealis; Introitus oesophagi
- Synonym: Upper esophageal sphincter; Superior oesophageal sphincter
- Eponym: Mouth of Killian
- Related terms: Pharyngooesophageal constriction
Definition
The pharyngoesophageal constriction is the narrowest part of the pharynx and is located at the pharyngoesophageal junction, where the laryngopharynx becomes continuous with the esophagus at the level of the lower border of the cricoid cartilage (C6 vertebra). It is formed primarily by the cricopharyngeus muscle, the lower part of the inferior pharyngeal constrictor, which functions as the upper esophageal sphincter (UES).
Function
At rest, the cricopharyngeus remains tonically contracted, preventing the entry of air into the oesophagus and reflux of oesophageal contents into the pharynx. During swallowing, it relaxes transiently to allow the passage of the food bolus into the esophagus.
References
Bruss DM, Sajjad H. Anatomy, Head and Neck: Laryngopharynx. [Updated 2023 May 8]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026 Jan. Available from: https://www.ncbi.nlm.nih.gov/books/NBK549913/
Merea, V.S. and Pitman, M.J. (2019) 'Anatomy and physiology of the upper esophageal sphincter', in Dysphagia Evaluation and Management in Otolaryngology. Amsterdam: Elsevier, pp. 29-34.
