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The occipital bone overlies the occipital lobes of the cerebrum. At the base of the skull in the occipital bone, there is a large oval opening called the foramen magnum, which allows the passage of the spinal cord. Like the other cranial bones, it is classed as a flat bone. Due to its many attachments and features, the occipital bone is ...
The base of the cranium is formed from a ring of bones surrounding the foramen magnum and a median bone lying further forward; these are homologous with the occipital bone and parts of the sphenoid in mammals. Finally, the lower jaw is composed of multiple bones, only the most anterior of which (the dentary) is homologous with the mammalian ...
The full complement of bones of the tetrapod skull roof, as seen in the temnospondyl Xenotosuchus. The skull roof or the roofing bones of the skull are a set of bones covering the brain, eyes and nostrils in bony fishes and all land-living vertebrates. The bones are derived from dermal bone and are part of the dermatocranium.
1 occipital bone; 2 parietal bones; 1 sphenoid bone; 2 temporal bones; The ossicles (three on each side) are usually not included as bones of the neurocranium. [6] There may variably also be extra sutural bones present. Below the neurocranium is a complex of openings and bones, including the foramen magnum which houses
The facial bones usually form into pairs and then fuse together. As the cranium fuses, sutures are formed that resemble stitching between bone plates. In a newborn, the junction of the parietal bones with the frontal and occipital bones, form the anterior (front) and posterior (back) fontanelle, or soft spots.
The fusion of the skull's bones before birth is known as craniosynostosis. The term " fontanelle " is used to describe the resulting "soft spots". The relative positions of the bones continue to change during the life of the adult (though less rapidly), which can provide useful information in forensics and archaeology .
Most bones of the calvaria consist of internal and external tables or layers of compact bone, separated by diploë. The diploë is cancellous bone containing red bone marrow during life, through which run canals formed by diploic veins. The diploë in a dried calvaria is not red because the protein was removed during preparation of the cranium.
Facial bones of the skull are not included in the cranial cavity. There are only eight cranial bones: The occipital, sphenoid, frontal, ethmoid, two parietal, and two temporal bones are fused together by the ossification of fixed fibrous sutures. The frontal and sphenoid bones are towards the front middle of the skull and in front of the ...