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Attachment of inferior head of lateral pterygoid muscle

The inferior head of the lateral pterygoid muscle is a crucial muscle of mastication, primarily responsible for opening the jaw and assisting in lateral movements of the mandible. Its precise anatomical attachment and imaging characteristics are essential for accurate assessment in clinical and radiological practice, particularly in the context of temporomandibular joint (TMJ) disorders.

Anatomical Attachment:

  • The inferior head of the lateral pterygoid muscle originates from the lateral surface of the lateral pterygoid plate of the sphenoid bone.

  • It inserts primarily into the pterygoid fovea located on the anteromedial aspect of the neck of the mandibular condyle.

  • Some fibers may also blend with the articular disc and capsule of the TMJ.

  • This attachment plays a pivotal role in mandibular movement and TMJ stability.

Synonyms:

  • Lateral pterygoid muscle, inferior head

  • Inferior belly of lateral pterygoid

  • Lower head of lateral pterygoid

  • Musculus pterygoideus lateralis caput inferius (Latin)

MRI Appearance:

1. Proton Density (PD) Sequence:

  • The muscle appears as a well-defined, intermediate signal intensity structure.

  • Located in the infratemporal fossa, extending from the lateral pterygoid plate to the mandibular condyle.

  • The attachment at the pterygoid fovea is often visualized as a linear or fan-shaped region of intermediate signal.

  • The adjacent condylar cortex appears as a low-signal-intensity line.

  • Muscle integrity, bulk, and any asymmetry can be evaluated clearly in this sequence.

2. Short Tau Inversion Recovery (STIR) Sequence:

  • The inferior head of the lateral pterygoid muscle demonstrates intermediate signal intensity on STIR.

  • Any edema, inflammation, or pathology (such as myositis or injury) will appear hyperintense (bright) compared to the normal muscle.

  • The muscle’s attachment point can be differentiated from surrounding fatty tissue and joint structures due to contrast in signal intensities.

  • STIR is especially useful in detecting subtle soft tissue abnormalities or edema involving the lateral pterygoid muscle or its attachment.

MRI images

Attachment of inferior head of lateral pterygoid muscle