Head and neck muscles (chewing, facial, and throat muscles)

Inferior pharyngeal constrictor

Musculus constrictor pharyngis inferior

Origin

Lateral borders of the thyroid cartilage and the cricoid cartilage (cricopharyngeal part)

Insertion

Median pharyngeal raphe at the back of the pharynx

Function

Constricts the lower pharynx during swallowing; the cricopharyngeal part acts as the upper esophageal sphincter, normally closed and relaxing only during swallowing

Innervation

Pharyngeal plexus (CN IX and CN X); cricopharyngeal part also via the recurrent laryngeal nerve

Movement & chain

Works in a peristaltic wave together with the middle and superior constrictors to propel the food bolus toward the esophagus.

Palpation

Not palpable through neck musculature; forms the deep muscular wall of the hypopharynx.

Clinical

Dysfunction of the cricopharyngeal sphincter can contribute to dysphagia and is relevant in Zenker's diverticulum (an outpouching just above this muscle).

Segmental innervation

CN IX/CN X, motor via the pharyngeal plexus.

In clinical practice

Inferior fibers form the cricopharyngeus (UES); targeted by cricopharyngeal myotomy or Botox injection for Zenker's diverticulum and dysphagia.

Region in the model

Head and neck muscles (chewing, facial, and throat muscles)