The skull is part of the skeleton, houses and protect the brain and the major sense organs.Important features include the nasal passages, containing the turbinals, which are delicate scrolls of paper thin bone, the orbits or eye sockets, the teeth bearing maxilla, or upper jaw, and mandible, or lower jaw, the zygomatic, arches, or cheekbones, the auditory bulla (in mammals), housing the bones of the middle ear; the formen magnum, a large opening through which the brain connects with the spinal cord; and mainly minute passage for nerves and blood vessels.

The deep skull bones that develop from cartilage are known as endochondrial bones, the superficial bones, including those of the face, develop directly from connective tissue membrane and are called dermal bones, or membrane bones. Most human skull bones are united, often across a wavy sufure, by connective fibrous tissue; a few are united by cartilage. Primitive land vertebrates had more than 50 paired skull bones, only 26 of these bones persist in humans and other mammals. In adult humans the braincase has a capacity of about 1,400 cm3 (85 in3) of soft tissue.


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