Body Organs

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...

The human skeletal system is composed of individual bones and cartilage that receive a supply of blood and are held together by fibrous connective tissue, ligamens, and tendons. The three main fuctions of the skeletal system are protection, motion, and support. The system protect the body by enclosing the vital organs, it permits locomotion by responding at certain joints to the contractile activities of skeletal muscles, and it supports the body by serving as a framework to which tendons and fascia are attached, enabling skeletal muscles as a depot for calcium, which is vital to proper functioning of cell membranes, and for phosporus, which is needed in intermediary metabolism. In addition, the skeletal system is important because bone produce blood cells. A birth the human body has about 275 bones, but as the body develops many of these bones fuse together. In the adult human the skeleton consist of 206 name bearing bones and a variable number of largely unnamed sesamoid bones. Ses...