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Attachment of superior head of lateral pterygoid muscle

The superior head of the lateral pterygoid muscle plays a crucial role in jaw movement and temporomandibular joint (TMJ) dynamics. Its anatomical attachment and imaging characteristics are important in radiological assessment, particularly on MRI for evaluating TMJ disorders, muscle pathology, or local tumors.

Anatomical Attachment:

  • The superior head of the lateral pterygoid muscle originates primarily from the infratemporal surface and crest of the greater wing of the sphenoid bone.

  • Its fibers run horizontally and slightly backward, inserting mainly into the articular disc and capsule of the TMJ, with some fibers also attaching to the pterygoid fovea on the anterior aspect of the mandibular condyle.

  • This anatomical arrangement enables the muscle to assist in opening the jaw, protruding the mandible, and stabilizing the TMJ during movement.

Synonyms:

  • Upper head of lateral pterygoid muscle

  • Superior belly of lateral pterygoid

  • Caput superior musculi pterygoidei lateralis (Latin)

  • Superior division of lateral pterygoid muscle

MRI Appearance:

Proton Density (PD) Sequence:

  • On PD MRI, the superior head appears as an intermediate signal intensity structure.

  • The muscle is seen lateral to the lateral pterygoid plate, anterior to the mandibular condyle, and closely associated with the TMJ capsule.

  • Its fibers are typically distinguishable from adjacent fat and bone marrow, aiding in anatomical delineation.

Short Tau Inversion Recovery (STIR) Sequence:

  • On STIR images, the superior head also demonstrates intermediate signal but is more conspicuous due to fat suppression.

  • Pathological changes (such as edema or inflammation) are more easily detected on STIR, appearing as areas of increased signal within or around the muscle.

  • The attachment to the TMJ disc and capsule is best visualized in coronal and axial planes.

MRI images

Attachment of superior head of lateral pterygoid muscle