Base of the skull. Upper surface. (Middle cranial fossa is the centermost of the three indentations, in pink and yellow.)
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|Latin
|colspan="2"|fossa cranii media
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|colspan="2"|[subject #47 ]
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|System
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|Precursor
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|MeSH
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|Dorlands/Elsevier
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The middle fossa, deeper than the anterior cranial fossa, is narrow in the middle, and wide at the sides of the skull.
It is bounded in front by the posterior margins of the small wings of the sphenoid, the anterior clinoid processes, and the ridge forming the anterior margin of the chiasmatic groove; behind, by the superior angles of the petrous portions of the temporals and the dorsum sellæ; laterally by the temporal squamæ, sphenoidal angles of the parietals, and great wings of the sphenoid. It is traversed by the squamosal, sphenoparietal, sphenosquamosal, and sphenopetrosal sutures.
Behind the tuberculum sellæ is a deep depression, the sella turcica, containing the fossa hypophyseos, which lodges the hypophysis, and presents on its anterior wall the middle clinoid processes.
The sella turcica is bounded posteriorly by a quadrilateral plate of bone, the dorsum sellæ, the upper angles of which are surmounted by the posterior clinoid processes: these afford attachment to the tentorium cerebelli, and below each is a notch for the abducent nerve.
On either side of the sella turcica is the carotid groove, which is broad, shallow, and curved somewhat like the italic letter f.
It begins behind at the foramen lacerum, and ends on the medial side of the anterior clinoid process, where it is sometimes converted into a foramen (carotico-clinoid) by the union of the anterior with the middle clinoid process; posteriorly, it is bounded laterally by the lingula.
The lateral parts of the middle fossa are of considerable depth, and support the temporal lobes of the brain.
They are marked by depressions for the brain convolutions and traversed by furrows for the anterior and posterior branches of the middle meningeal vessels.
These furrows begin near the foramen spinosum, and the anterior runs forward and upward to the sphenoidal angle of the parietal, where it is sometimes converted into a bony canal; the posterior runs lateralward and backward across the temporal squama and passes on to the parietal near the middle of its lower border.
The following apertures are also to be seen.
In front is the superior orbital fissure, bounded above by the small wing, below, by the great wing, and medially, by the body of the sphenoid; it is usually completed laterally by the orbital plate of the frontal bone.
Medial to the foramen ovale is the foramen Vesalii, which varies in size in different individuals, and is often absent; when present, it opens below at the lateral side of the scaphoid fossa, and transmits a small vein.
Lateral to the foramen ovale is the foramen spinosum, for the passage of the middle meningeal vessels, and a recurrent branch from the mandibular nerve.
Medial to the foramen ovale is the foramen lacerum; in the fresh state the lower part of this aperture is filled up by a layer of fibrocartilage, while its upper and inner parts transmit the internal carotid artery surrounded by a plexus of sympathetic nerves.
