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: 3 : The Skeleton: Muscles: Skin
The Skin
The 206 bones of the average adult skeleton work together with the muscles and connective tissues to move, support and protest the vital organs making up the human body. It enables us to run, jump and control overselves with a freedom unknown amongst our mechanical creations. Each individual bone is carefully designed to fulfil its role. Ranging in size from the powerful thigh bone (femur) about 500 mm long and 25 mm across-to the smallest of the wrist bones found at the base of the little finger and shaped like a split-pea. The former must withstand 1200 lbs per square rich during walking; hence it is filled with crosshatching internally for great resistance to pressure. Protection of the brain is one of the most important functions. The skull is made up of eight pieces of bone.
Spine or vertebral column is a marvel of efficient engineering and functionalism. Its vertebrae are formed to compose a cylindrical column strong enough to provide support for the body, yet flexibly articulated to provide for bending, stooping, twisting and a variety of other body motions.
An intervertebral disc of compressible fibrous cartilage is sandwiched between each two adjacent vertebrae cushioning the joint. With this structure, the vertebral column can withstand forces of compression many times the weight of the body.
It prot
The rib cage is an excellent example of the versatilty of joints and the protective function of skeleton. ects two delicate organs-lungs and heart, while being able to expand and contract to bring in fresh supplies of air. Cartilage joins the ribs to the breastbone, providing a
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