The cricopharyngeus is the lower part of the inferior pharyngeal constrictor that forms the upper oesophageal sphincter (UOS), maintaining tonic contraction at rest to prevent air entering the oesophagus during breathing and to prevent reflux of oesophageal contents into the pharynx. It must relax precisely in coordination with the swallowing sequence for the food bolus to enter the oesophagus, and failure of this relaxation (cricopharyngeal dysfunction) causes the pressure build-up that herniates through Killian's dehiscence to form a Zenker diverticulum.
| Origin | Lateral surface of the cricoid cartilage |
|---|---|
| Insertion | Posterior cricoid cartilage, meeting the opposite muscle at the midline |
| Nerve Supply | Pharyngeal plexus (CN X); Recurrent laryngeal nerve (CN X) |
| Blood Supply | Inferior thyroid artery |
| Actions | Tonic contraction at rest forms the upper oesophageal sphincter; Relaxes immediately before the food bolus arrives to allow oesophageal entry; Contracts again after passage to prevent oesophageal-to-pharyngeal reflux |
|---|
The coordinated relaxation of the cricopharyngeus requires intact vagal reflexes and brainstem swallowing centre function, explaining why neurological conditions affecting the brainstem produce cricopharyngeal dysfunction before peripheral pharyngeal muscle weakness.
Cricopharyngeal myotomy — surgical or endoscopic division of the cricopharyngeus — is performed for cricopharyngeal dysfunction causing dysphagia, Zenker diverticulum, and post-laryngectomy dysphagia. Botulinum toxin injection into the cricopharyngeus under EMG guidance is used as a diagnostic and therapeutic alternative to surgery for functional cricopharyngeal spasm.
Not accessible to external palpation. Assessed by videofluoroscopic swallow study showing the UOS opening pattern.
Failure of UOS relaxation producing transfer dysphagia and aspiration managed with cricopharyngeal myotomy or Botulinum toxin injection.
