Pterygoid processes

Last revised by Joel Hng on 18 Jan 2024

The pterygoid processes or pterygoid plates are paired posteroinferior projections of the sphenoid bone.

Each pterygoid process projects inferiorly from the junction of the body and greater wing of the sphenoid bone and bifurcates into a medial pterygoid plate and a lateral pterygoid plate. At the inferior tip of the medial pterygoid plate is the small hook-shaped process, the pterygoid hamulus. 

The spaces separated the medial and lateral plate are pterygoid fissure inferiorly and pterygoid fossa posterosuperiorly. The lateral aspect of the lateral pterygoid plate forms the medial wall of the infratemporal fossa. The root of the pterygoid process forms the posterior wall of the pterygopalatine fossa. The anterior opening of the pterygoid canal also sits on the anterior aspect of the root of the pterygoid process.

The pterygoid hamulus has two important relations, related to its function:

  • lateral pterygoid muscle: the lower part of the lateral pterygoid is attached to the lateral aspect of the lateral pterygoid plate

  • medial pterygoid muscle: medial aspect of the lateral pterygoid plate

  • superior pharyngeal constrictor: inferior end of the medial pterygoid plate

  • tensor veli palatini: scaphoid fossa of medial pterygoid plate

Pterygoid plates are important in diagnosing midface fractures. In the Le Fort classification of midface fractures, the pterygoid plate involvement is necessary to confirm the diagnosis.

"Pterygoid" derives from the classical Greek words "πτερον" (wing) and "είδος" (-like) 2.

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