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Middle constrictor muscle of pharynx

The middle constrictor muscle is one of the three paired pharyngeal constrictor muscles that form the muscular wall of the pharynx. Located between the superior and inferior constrictor muscles, it plays a vital role in swallowing by contracting sequentially to propel food from the oropharynx into the esophagus. This fan-shaped muscle wraps around the pharynx and is crucial for normal deglutition. Its anatomical relationships and imaging features are essential for clinicians, radiologists, and surgeons in evaluating pharyngeal pathologies.

Synonyms:

  • Musculus constrictor pharyngis medius

  • Middle pharyngeal constrictor

  • Constrictor pharyngis medius muscle

Function:

  • Contracts during swallowing to constrict the pharyngeal wall

  • Propels the food bolus downward from the oropharynx to the esophagus

  • Coordinates with superior and inferior constrictor muscles in the act of deglutition

Origin:

  • Greater horn (cornu) of the hyoid bone

  • Lesser horn of the hyoid bone

  • Stylohyoid ligament

Insertion:

  • Median pharyngeal raphe (a midline tendinous seam running along the posterior pharyngeal wall)

Nerve Supply:

  • Pharyngeal plexus (formed by branches of the vagus nerve [cranial nerve X] with motor fibers originating from the cranial part of the accessory nerve [cranial nerve XI])

Artery Supply:

  • Ascending pharyngeal artery (branch of external carotid artery)

  • Tonsillar branch of the facial artery

  • Dorsal lingual branches of the lingual artery

Vein Supply:

  • Pharyngeal venous plexus

  • Drains primarily into the internal jugular vein

MRI Appearance:

  • T1-weighted images: The middle constrictor muscle appears as a low-to-intermediate signal intensity structure forming part of the pharyngeal wall.

  • T2-weighted images: Normal muscle demonstrates relatively low signal intensity, but increased signal may indicate edema or pathology. 

  • STIR (Short Tau Inversion Recovery): The muscle typically demonstrates low signal intensity unless pathology is present (such as edema or inflammation, which would increase signal intensity).

CT Appearance:

  • Appears as a soft tissue density, isodense to adjacent muscle groups.

  • Outlines the lateral wall of the pharynx between the superior and inferior constrictor muscles.

MRI images

Middle constrictor muscle of pharynx mri axial image