n :  either of two vertical plates making up a pterygoid process of the sphenoid bone:  a  :  a broad thin plate that forms the lateral part of the pterygoid process and gives attachment to the lateral pterygoid muscle on its lateral surface and to the medial pterygoid muscle on its medial surface - called also lateral pterygoid plate   b  :  a long narrow plate that forms the medial part of the pterygoid process, terminates in the pterygoid hamulus, and forms with its lateral surface part of the pterygoid fossa and with its medial surface the lateral boundary of a choana - called also medial pterygoid plate  .
 
 
 
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