Fossa navicularis magna (also known as pharyngeal fossaorphyaryngeal fovela) is a variant bony depression found at the midline of the occipital part of clivus. This fossa was first described by Tourtual.[1] Its prevalence ranges from 0.9 to 5.3%.[2]
Fossa navicularis magna is located on the anterior surface or pharyngeal surface of the clivus. Its position when present is between the spheno-occipital synchondrosis and the foramen magnum. Size of this fossa varies considerably and its depth ranges from 3.49 to 4.94 mm.[3] A histological study reported the presence of loose connective tissue containing collagen and elastic fibers within the fossa navicularis magna.[4]
Two theories have been proposed to explain the formation of fossa navicularis magna. It is believed that the fossa is formed as a remnant of the notochord or residue of the channels for emissary veins.[5]
Different pathologies were found associated with fossa navicularis magna including cancers, adenoid hypertrophy, ecchordosis physaliphora, Tornwaldt cyst and Rathke cleft cyst.[6]
