cricopharyngeus

The cricopharyngeus is the cricopharyngeal portion of the inferior pharyngeal constrictor and forms the upper esophageal sphincter (UES). It is located at the level of the cricoid cartilage and provides the muscular component that regulates opening between the pharynx and the esophagus.

Functionally, the cricopharyngeus remains tonically contracted at rest to help prevent air entry and reflux. During swallowing, neural coordination suppresses its tone while the surrounding pharyngeal muscles and esophageal peristalsis propel the bolus into the esophagus, allowing a timely and controlled opening of the UES.

Innervation of the cricopharyngeus is via the pharyngeal plexus, primarily containing motor fibers from the vagus nerve (cranial nerve X). This makes it part of the coordinated pharyngeal swallow reflex.

Clinically, dysfunction of the cricopharyngeus can contribute to dysphagia, with symptoms such as difficulty swallowing both solids and liquids, regurgitation, coughing, or aspiration. A cricopharyngeal bar may be seen on imaging, and chronic dysfunction can be associated with the development of a Zenker diverticulum due to increased or uncoordinated UES pressure.

Diagnosis typically involves videofluoroscopic swallow studies and esophageal manometry to assess UES opening and muscle tone, sometimes along with endoscopy to exclude other lesions. Treatment for symptomatic cricopharyngeus dysfunction may include cricopharyngeal dilation, botulinum toxin injection, or cricopharyngeal myotomy (endoscopic or open) to reduce UES pressure and improve bolus transit.