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Superior pharyngeal constrictor muscle

The superior pharyngeal constrictor is the uppermost of the three pharyngeal constrictor muscles forming the muscular wall of the nasopharynx and oropharynx. It is a thin quadrilateral sheet that curves posteriorly to form the upper pharyngeal wall and contributes to the pharyngeal raphe.

It plays a major role in swallowing, initiating peristaltic contraction of the pharyngeal wall and coordinating with the soft palate to prevent nasopharyngeal reflux. Its anatomical continuity with surrounding muscles—including the buccinator, palatopharyngeus, and pterygomandibular structures—forms a functional oropharyngeal sphincter.

Synonyms

  • Constrictor pharyngis superior

  • Upper pharyngeal constrictor

Origin, Course, and Insertion

Origin:

  • Medial pterygoid plate (pterygoid hamulus)

  • Pterygomandibular raphe

  • Posterior end of mylohyoid line of mandible

  • Side of tongue

Course:

  • Fibers curve posteriorly and medially, wrapping around the upper pharynx

  • Superior fibers form part of the nasopharyngeal and oropharyngeal posterior wall

Insertion:

  • Midline pharyngeal raphe

  • Pharyngeal tubercle on the basilar part of the occipital bone

Relations

  • Anteriorly: Pterygomandibular raphe, buccinator muscle, medial pterygoid

  • Posteriorly: Retropharyngeal space and prevertebral fascia

  • Superiorly: Base of skull and pharyngobasilar fascia

  • Inferiorly: Middle pharyngeal constrictor muscle

  • Laterally: Parapharyngeal space, internal carotid artery, glossopharyngeal nerve region

Function

  • Initiates pharyngeal contraction during swallowing

  • Narrows the nasopharynx and oropharynx to help propel the bolus downward

  • Works with soft palate musculature to prevent food from entering the nasal cavity

  • Contributes to coordinated peristaltic movement of the pharyngeal wall

MRI Appearance

T1-weighted images:

  • Muscle demonstrates intermediate signal intensity, slightly darker than surrounding fat

  • Well-defined muscular borders forming part of the posterior and lateral pharyngeal wall

  • Pharyngeal mucosa appears slightly brighter than muscle

T2-weighted images:

  • Muscle displays intermediate-to-low signal intensity, darker than mucosa and brighter than cortical bone

  • Clear distinction between muscle, fat planes, and airway lumen

STIR:

  • Normal muscle shows intermediate-to-dark signal intensity

  • Fat suppression creates clear contrast between muscle and bright suppressed fat planes

T1 Fat-Saturated Post-Contrast:

  • Normal muscle shows mild, uniform enhancement

  • Enhances smoothly along the lateral and posterior pharyngeal wall

  • Pharyngeal mucosa displays brighter enhancement compared to deeper muscle fibers

CT Appearance

Non-Contrast CT:

  • Muscle appears as soft-tissue density forming the lateral and posterior pharyngeal wall

  • Surrounded by lower-density parapharyngeal and retropharyngeal fat

  • Pterygoid plates, mandible, and skull base landmarks are clearly visualized

Post-Contrast CT:

  • Superior pharyngeal constrictor shows subtle, homogeneous enhancement

  • Mucosa enhances more vividly than muscle

  • Clear delineation of pharyngeal wall thickness and adjacent fat planes

MRI images

Superior pharyngeal constrictor muscle mri axial image