pterygoid fossa pterygoid fossa the pterygoid fossa is an anatomical term for the fossa formed by the divergence of the lateral pterygoid plate and the medial pterygoid plate of the sphenoid bone. not to be confused with pterygoid fovea. pterygoid fossasphenoid bone. upper and posterior surfaces. (pterygoid fossa labeled at left.)detailsidentifierslatinfossa pterygoidea ossis sphenoidalista98a02.1.05.046ta2632fma84970anatomical terms of bone structure the lateral and medial pterygoid plates (of the pterygoid process of the sphenoid bone) diverge behind and enclose between them a v-shaped fossa, the pterygoid fossa. this fossa faces posteriorly, and contains the medial pterygoid muscle and the tensor veli palatini muscle. pterygoid fossa