Tonsillar fossa

The tonsillar fossa (or tonsillar sinus) is a space delineated by the triangular fold (plica triangularis) of the palatoglossal and palatopharyngeal arches within the lateral wall of the oral cavity. . The tonsillar fossa (or tonsillar sinus) is a space delineated by the triangular fold (plica triangularis) of the palatoglossal and palatopharyngeal arches within the lateral wall of the oral cavity. .