The bones теми 250стр The bone as an organ

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I. The bone as an organ - structure, development and growing.

Bone is d calcified, jiving, connective tissue that forms the majority of the skeleton. It consists of an intercellular calcIHed matrix, which also contains collagen fibers, and several types of cells within the matrix. c,.-£. i

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1) supportive structures for the body, , A ;

2) protectors of vital organs,

3) reservoirs of calcium and phosphorus,

4) levers on which muscles act to produce movement,

5) containers for blood-producing cells.

There are two types of bone, compact and spongy (trabecular or cancellous). Compact bone is dense bone that forms the outer shell of all bones and surrounds spongy bone. Spongy bone consists of spicules of bone enclosing cavities containing blood-forming cells (marrow).

Classification of bones: Cs^

1) Long bones are tubular (e.g., humerus in upper limb; femur in lower limb)

2) Short bones are cuboidal (e.g., bones of the wrist and ankle)

3) Flat bones consist of two compact bone plates separated by spongy bone (e.g., skull)

4) Irregular bones are bones with various shapes (e.g., bones of the face)

5) Sesamoid bones are round or oval bones that develop in tendons

periosteum will not survive. Nerves accompany the vessels that supply the bone and the periosteum. Most of the nerves passing into the internal cavity with the nutrient artery are vasomotor fibers that regulate blood flow. Bone itself has few sensory nerve fibers. On the other hand, the periosteum is supplied with numerous sensory nerve fibers and is very sensitive to any type of injury, .te^jpevelopmentally, all bones come from mesenchyme by either intramembranous ossification, in which mesenchymal models of bones undergo ossification, or endochondral ossification, in which caftilaginoiis models of bones form from mesenchyme and undergo ossification.

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Bones are vascular and are innervated. Generally, an adjacent artery gives off a nutrient artery. usually one per bone, that directly enters the internal cavity of the bone and supplies the marrow, spongy bone, and inner layers of compact bone. In addition, all bones are covered externally, except in the area of a joint where articular cartilage is present, by a fibrous connective tissue membrane called thbperiosteum, |yhich has the unique capability of forming new bone. This membrane receives blood vessels whose "branches supply the outer layers of compact bone. A bone stripped of its

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2. Bones of vertebral column. .(j

The major bones of the back are the 33 vertebrae.

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