- Body of sphenoid bone
Name = Body of sphenoid bone
Latin = corpus ossis sphenoidalis
GraySubject = 35
GrayPage = 147
Caption = Figure 2:
Sphenoid bone, anterior and inferior surfaces.
Caption2 = Figure 3: Sphenoid bone, upper and posterior surfaces.
DorlandsPre = c_56
DorlandsSuf = 12260702
The body of the
sphenoid bone, more or less cubical in shape, is hollowed out in its interior to form two large cavities, the sphenoidal air sinuses, which are separated from each other by a septum.
The superior surface of the body [Fig. 1] presents in front a prominent spine, the
ethmoidal spine, for articulation with the cribriform plateof the ethmoid bone; behind this is a smooth surface slightly raised in the middle line, and grooved on either side for the olfactory lobes of the brain.
This surface is bounded behind by a ridge, which forms the anterior border of a narrow, transverse groove, the
prechiasmatic groove, above and behind which lies the optic chiasma; the groove ends on either side in the optic foramen, which transmits the optic nerveand ophthalmic arteryinto the orbital cavity.
Behind the chiasmatic groove is an elevation, the
tuberculum sellae; and still more posteriorly, a deep depression, the sella turcica(the Turkish saddle), the deepest part of which lodges the pituitary glandand is known as the hypophyseal fossa.
The anterior boundary of the
sella turcicais completed by two small eminences, one on either side, called the middle clinoid processes, while the posterior boundary is formed by a square-shaped plate of bone, the dorsum sellae, ending at its superior angles in two tubercles, the posterior clinoid processes, the size and form of which vary considerably in different individuals.
The posterior clinoid processes deepen the sella turcica, and give attachment to the
On either side of the dorsum sellae is a notch for the passage of the
abducent nerve, and below the notch a sharp process, the petrosal process, which articulates with the apex of the petrous portion of the temporal bone, and forms the medial boundary of the foramen lacerum.
Behind the dorsum sellae is a shallow depression, the clivus, which slopes obliquely backward, and is continuous with the groove on the basilar portion of the
occipital bone; it supports the upper part of the pons.
The lateral surfaces of the body are united with the
greater wings of the sphenoidand the medial pterygoid plates.
Above the attachment of each greater wing is a broad groove, curved something like the italic letter f; it lodges the
internal carotid arteryand the cavernous sinus, and is named the carotid sulcus.
Along the posterior part of the lateral margin of this groove, in the angle between the body and greater wing, is a ridge of bone, called the
The posterior surface, quadrilateral in form [Fig. 3] , is joined, during infancy and adolescence, to the basilar part of the occipital bone by a plate of cartilage.
Between the eighteenth and twenty-fifth years this becomes ossified, ossification commencing above and extending downward.
The anterior surface of the body [Fig. 2] presents, in the middle line, a vertical crest, the sphenoidal crest, which articulates with the perpendicular plate of the
ethmoid, and forms part of the nasal septum.
On either side of the crest is an irregular opening leading into the corresponding
sphenoidal air sinus.
These sinuses are two large, irregular cavities hollowed out of the interior of the body of the bone, and separated from one another by a bony
septum, which is commonly bent to one or the other side.
They vary considerably in form and size, are seldom symmetrical, and are often partially subdivided by irregular bony laminae.
Occasionally, they extend into the
basilarpart of the occipital bonenearly as far as the foramen magnum. They begin to be developed before birth, and are of a considerable size by the age of six.
They are partially closed, in front and below, by two thin, curved plates of bone, the
sphenoidal conchae, leaving in the articulated skull a round opening at the upper part of each sinus by which it communicates with the upper and back part of the nasal cavity and occasionally with the posterior ethmoidal air cells.
The lateral margin of the anterior surface is serrated, and articulates with the
lamina papyraceaof the ethmoid, completing the posterior ethmoidal cells; the lower margin articulates with the orbital process of the palatine bone, and the upper with the orbital plate of the frontal bone.
The inferior surface presents, in the middle line, a triangular spine, the
sphenoidal rostrum, which is continuous with the sphenoidal crest on the anterior surface, and is received in a deep fissure between the alæ of the vomer.
On either side of the rostrum is a projecting
lamina, the vaginal process, directed medialward from the base of the medial pterygoid plate, with which it will be described.
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