Bone is a type of connective tissue and like all tissues it is composed of cells actively engaged in physiologic pursuits. Some of these cells produce the rocklike bone substance, while others bring about the dissolution of this substance for the purpose of supplying calcium to the blood. Furthermore, certain cells in the red bone marrow manufacture blood corpuscles at a prodigious rate. It is estimated that about 1 million worn-out red blood corpuscles are destroyed every second, and quite obviously new ones must be produced to replace them. Failure of the red marrow to comply leads to anemia and, if nonreversible, ultimately to death. Finally, the skeletal system brackets all the other systems, and in so doing it serves as a logical introduction to the human body.

The skeletal system consists of bones and articulations. Articulation are the joints between the bones; bands of fibrous tissue, called ligaments, serve to support and strengthen joints. The system performs or is associated with five functions; support, protection, movement, calcium metabolism, and blood cell formation.

Bones serve as the supporting framework of the body in much the same way as steel girders function in supporting a building. As bony "boxes" they protect delicate structures within. In conjunction with joints (which act as fulcrums) and muscles, bones allow movement. Bone serve as the major reservoir into which calcium is deposited or from which it is withdrawn, the nature of the shift depending on body needs. Finally, the red marrow within the bones manufactures blood cells. In the adult, this activity, called hemopoiesis, is most prominent in the ribs, sternum, vertebrae, and cranial bones.

The Names of The Bones
The anatomic name of a bone is of Latin or Greek origin. Just who did the naming is probably lost to the past, but oe thing remains quiue clear- they had imagination. Coccyx, for example, the small bone at the base of the spinal column, derives from" kokkux", the Greek word for cuckoo. And this bone does indeed look like a cuckoo's beat. A great many bones have acquired common names: breastaone for sternum; shinbone for tibia; heel bone for calcaneus; shoulder blade for scapula, and so on.Some anatomic names refer to a skeletal part rather than a specific bone. For example, carpus -the wrist-is composed of 8 carpal bones, each with its own special name.