Skull Notes

Osteology Skull Bones Frontal, Occipital, Parietal, Squamous and petrous temporal, External acoustic meatus, Zygomatic, Greater and lesser wings of sphenoid, Cribriform plate, Clinoid processes, The pituitary fossa Temporal Bone Sphenoid bone Clinoid process Cribiform plate: Pituitary fossa Core: anterior cranial fossa -The anterior cranial fossa (frontal, ethmoid, sphenoid bones) supports the frontal lobes of the brain. - It is limited anteriorly and laterally by the frontal bone. Anterior wall of the fossa has the frontal air sinus - In the midline of the floor of the anterior cranial fossa is body of the sphenoid and the ethmoid bone- midline there is a sharp ridge- crista galli- provides attachment for the falx cerebri. In depression on either side of crista galli- cribiform plates of the ethmoid- these accomadate the olfactory bulbs -Bone of the cribriform plates has small perforations through which fascicles of olfactory nerve enter cranial cavity from nasal cavity to attach to the olfactory bulb -Laterally, the fossa is bordered by the orbital part of the frontal bone and the lesser wing of the sphenoid. -The anterior clinoid process arises from the medial aspect of the sphenoid. Core: middle cranial fossa -The middle fossa is much deeper than the anterior fossa. The middle cranial fossa supports the temporal lobes of the brain, the hypothalamus and the pituitary. -Curving ventrally from the lesser wing and separated from it by the superior orbital fissure, the greater wing of the sphenoid is deeply concave and forms the anterior part of the middle cranial fossa. -The greater wing of the sphenoid articulates with the anterior borders of the squamous temporal bone laterally and the petrous part postero-medially. -The body of the sphenoid is cubical and forms the floor of the middle cranial fossa in the midline. Anteriorly is articulates with the cribriform plate; posteriorly the chiasmatic sulcus leads laterally to the optic canal. -Behind the chiasmatic sulcus, the elevation, the tuberculum sellae descends into the hollow, the sella turcica, the deepest part of which forms the pituitary fossa. Posteriorly, the sella turcica is limited by a square plate of bone, the dorsum sellae which gives rise to two tubercles, the posterior clinoid processes. 

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