Topics

Topic

design image
Superior constrictor muscle of pharynx

The superior constrictor muscle is a thin, quadrilateral muscle forming the uppermost part of the pharyngeal constrictor muscles. It plays a crucial role in the process of swallowing by helping to constrict the upper pharyngeal wall, facilitating the downward movement of a food bolus into the esophagus. This muscle contributes to the formation of the pharyngeal wall, specifically at the nasopharynx and oropharynx level, and is key for maintaining the integrity of the pharyngeal space during deglutition.

Anatomical Points:

Function:

  • Constricts the upper part of the pharyngeal wall during swallowing.

  • Initiates the peristaltic movement pushing the food bolus downward.

  • Helps close off the nasopharynx during swallowing, preventing regurgitation.

Origin:

  • Pterygoid hamulus (of the medial pterygoid plate of sphenoid bone)

  • Pterygomandibular raphe

  • Posterior end of the mylohyoid line of the mandible

  • Side of the tongue

Insertion:

  • Median pharyngeal raphe (midline tendinous seam at the posterior wall of the pharynx)

  • Some fibers blend with the pharyngeal tubercle of the occipital bone

Nerve Supply:

  • Pharyngeal plexus via the pharyngeal branch of the vagus nerve (cranial nerve X), which receives motor fibers from the cranial part of the accessory nerve (cranial nerve XI).

Arterial Supply:

  • Ascending pharyngeal artery (branch of the external carotid artery)

  • Branches from the facial artery

  • Branches from the lingual artery

  • Branches from the maxillary artery

Venous Drainage:

  • Drains into the pharyngeal venous plexus

  • Venous plexus drains into the internal jugular vein

MRI Appearance:

  • T1-weighted images:

    • Appears as intermediate to low signal intensity (similar to other skeletal muscles)

  • T2-weighted images:

    • Appears as relatively low signal intensity, unless pathology (such as edema or tumor infiltration) increases signal

  • STIR (Short Tau Inversion Recovery):

    • Normally low signal; areas of muscle inflammation, edema, or tumor infiltration show high signal intensity

CT Appearance:

  • Appears as a thin, soft tissue density band forming the upper part of the pharyngeal wall

  • Clearly demarcated from the surrounding fat and air spaces; muscle is distinguishable by its soft tissue attenuation

MRI images

Superior constrictor muscle of pharynx mri axial image -img-00000-00000