The =body= (Corpus) is a cylindrical bar, flattened dorso-ventrally, and wider in front than behind. Its =ventral surface= (Facies externa) is convex in the transverse direction; and its anterior part is concealed to a large extent by the vomer and pterygoid bones. The =cerebral surface= (Facies cerebralis) presents the following features: (1) In front is a raised, flattened part which is subdivided by a median elevation into two slightly concave lateral areas; this part has a posterior, thin, free margin (Limbus sphenoidalis), which overlies the entrance to the optic foramina. (2) Just behind this and at a lower level is a smooth transverse depression, the =optic groove= (Sulcus chiasmatis), on which the optic chiasma rests. (3) From each end of this groove the =optic foramen= passes forward and outward to terminate in the posterior part of the orbital fossa.[9] (4) Near the posterior end is a central depression, the =hypophyseal= or =pituitary fossa= (Fossa hypophysea), which lodges the hypophysis cerebri or pituitary body. On each side of this is an ill-defined groove for the internal carotid artery and the cavernous sinus. The =anterior end= is expanded, and is excavated to form the =sphenoidal sinuses.= These cavities extend back as far as the optic groove, and are usually continuous in front with the cavities in the vertical parts of the palate bones; they are separated by a complete septum which is not always median.[10] The =posterior end= is flat and is joined to the basilar part of the occipital; at the line of junction there is dorsally a transverse elevation, the =spheno-occipital= crest (Crista sphenooccipitalis).