The frontal sinuses lie deep to the brow ridges. It lies superior to the nasion and between the superciliary ridges. The glabella is a key midline landmark of the frontal bone. It is composed of the sphenoid and ethmoid bones (which have their associated air sinuses) and parts of the frontal, temporal, and occipital bones.Īnteriorly, the frontal bone forms the superior aspect of the orbits. Finally, the skull base allows the passage of various neurovascular structures. The asterion is the articulation of the parietal, temporal, and occipital bones. The pterion is the articulation of the frontal, parietal, temporal, and sphenoid bones just superior to the pinna. The sagittal suture lies along an anterior-posterior axis and is the articulation of the two parietal bones. The parietal bones articulate with the temporal bones inferiorly via the squamosal sutures and the occipital bone posteriorly via the lambdoid suture. The coronal suture is the transverse mid-anterior junction of the frontal bone and the two parietal bones. It is composed of the frontal bone, parietal bones, temporal bones, and occipital bone. The calvaria, the uppermost part of the skull, protects the cerebral cortex, cerebellum, and orbital contents. In addition, it supports the muscles of the face and scalp by providing muscular and tendinous attachments, protects neurovascular structures, and houses various sinuses to accommodate increases in pressure. The skull will harden and fuse through development to protect its inner contents: the cerebrum, cerebellum, brainstem, and orbits. The function of the skull is both structurally supportive and protective. It contains a small opening for passage of the stalk of the pituitary gland.The skull consists of 22 bones in most adult specimens, which come together via cranial sutures. Diaphagma sellae - covers the hypophysial fossa of the sphenoid bone.Falx cerebelli - separates the right and left cerebellar hemispheres.It contains a space anteromedially for passage of the midbrain - the tentorial notch. Tentorium cerebelli - separates the occipital lobes from the cerebellum.Falx cerebri - projects downwards to separate the right and left cerebral hemispheres.These reflections project into the cranial cavity, dividing it into several compartments - each of which houses a subdivision of the brain. It is innervated by the trigeminal nerve (V1, V2 and V3). The dura mater receives its own vascular supply - primarily from the middle meningeal artery and vein. It is continuous with the dura mater of the spinal cord. Meningeal layer - located deep to the periosteal layer.Periosteal layer - lines the inner surface of the bones of the cranium.Fig 1 - Overview of the meninges, and their relationship to the skull and brain. It contains a small opening for passage of the stalk of the pituitary gland. Diaphagma sellae – covers the hypophysial fossa of the sphenoid bone.Falx cerebelli – separates the right and left cerebellar hemispheres.It contains a space anteromedially for passage of the midbrain – the tentorial notch. Tentorium cerebelli – separates the occipital lobes from the cerebellum.Falx cerebri – projects downwards to separate the right and left cerebral hemispheres.These reflections project into the cranial cavity, dividing it into several compartments – each of which houses a subdivision of the brain. The meningeal layer of dura mater folds inwards upon itself to form four dural reflections. The dura mater receives its own vascular supply – primarily from the middle meningeal artery and vein. They are responsible for the venous drainage of the cranium and empty into the internal jugular veins. The dural venous sinuses are located between the two layers of dura mater. Meningeal layer – located deep to the periosteal layer.Periosteal layer – lines the inner surface of the bones of the cranium.The dura mater consists of two layered sheets of connective tissue: The dura mater is the outermost layer of the meninges and is located directly underneath the bones of the skull and vertebral column.
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