Cricopharyngeus
Tongue & Throat
The main functional upper esophageal sphincter — dysfunction here causes Zenker's diverticulum, where food pouches out above it and can regurgitate hours later.
Function
Maintains upper esophageal sphincter tone; relaxes during swallowing
Origin
Lateral cricoid cartilage
Insertion
Circular fibers around pharyngoesophageal junction
Innervation
Vagus nerve (CN X), mainly pharyngeal plexus/recurrent laryngeal contributions