Bones Skeleton= dried up. Skeleton is made of bones, joints, cartilage and ligaments. Ligament= join bones. Tendon= join bone to muscle. Two subdivisions: 1. axial = form longitudinal to body 2. appendicular= limbs, and girdles.

Functions „

Support : Support and anchors organs

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Protection: Protect organs

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Movement: walk, swim, dance…

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Storage: Minerals.

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Blood cell Formation: Hematopoiesis.

Classification „

206 bones

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Two basic types „

Compact bone: dense, smooth and homogeneous

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Spongy bone: small needlelike and lots of open space.

Types of Bones

Compact Bone

Classification by Shape „

According to shape bones can be classified as Long bone „ Short bone „ Flat bone „ Irregular bone „

Long Bone „ „

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They are longer than wider. Long bones have a long shaft with heads at both ends. They are formed by compact bone. Limb bones are long bones.

Short bone „ „ „

Generally cubed shaped. Made mostly of spongy bone. Bones from wrist and ankle.

Flat Bones „ „

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They are thin, flattened, and usually cured. They have two thin layers of compact bone sandwiching a layer of spongy bone between them. Most bone of skull, ribs and sternum are flat bones.

Irregular Bones „

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Bones that do not fit in any of the preceding categories are called irregular bones. Hip bones and the vertebrae are considered irregular bones.

Bone markings „ „ „

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Surfaces in bones are not smooth. Bones are full of holes, ridges and bumps. These features create bone markings, and show where tendons, muscles and ligaments were attached, and where blood vessels and nerves passed. Example : sinuses in your face.

Bones markings „

Two categories of bone markings: „

1. projections or processes : grow from bone surface. Example: The head of the femur.

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2. Depressions or cavities: They are indentations in the bone. Example : Foramen magnum, which is the baby’s soft spot in the top of the head.

Structure of a Long Bone Gross Anatomy epiphysis

diaphysis

Distal epiphysis

Structure of Long Bone Gross Anatomy „

Diaphysis: It is called shaft too. „ It makes most of bone’s length. „ Composed of compact bone „ It is covered by a fibrous connective tissue called periosteum. „ Sharpey’s fibers, secure the periosteum to the underlying bone. „

Structure of Long Bone Gross Anatomy „

Epiphysis They are the ends of a long bone „ Consist of a thin layer of compact bone filled with spongy bone. „ Articular catilage covers the external surface „ Articular cartilage is glassy hyaline cartilage, and provides a smooth and slippery surface that decrease friction at joint surfaces. „

Ephyseal Line and Plate „

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Epiphyseal Line is a line found in the epiphysis of the bone in adults. Epiphyseal Plate is an area in the ephiphysis that allows the bone to grow. Epiphyseal Plate is found in young people because the bone is still growing.

Yellow/Red Marrow „

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The cavity of the shaft is primary storage for fat or yellow marrow. In infants this area forms blood cells, that is why is called red marrow. Red marrow is found in the cavities of spongy bone of flat bones, and the epiphysis of some long bones.

Microscopic Anatomy „

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Bones have a lot of passages that carry nerves, blood vessels, these passages provide the living bone cells with nutrients and waste for disposal. Osteocytes= mature bone cells. Lacunae= tiny cavities in the matrix, where osteocytes are located. Lamellae= concentric circles in the lacunae Central canals in the bone= Harvesian canals

Microscopic Anatomy „ „

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Each complex consisting of a central canal and matrix rings is called osteon or Harvesian system. Central canals run lenghtwise through the bony matrix, carrying blood vessels and nerves to all areas of the bone. Tiny canals, called canliculi radiate outward from the central canal to all lacunae. The canaliculi form a transportation system. Connects all the bone cells to the nutrients of the matrix. The communication between the outside of the bone, and the inside is completed by Volkman’s canals.

Microscopic Bone