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*Bone is a type of connective tissue where the matrix is hard and calcified. The matrix contains many collagen fibers. The term for these layers of the matrix is Lamellae.
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Each of these dark spots in the graphic is an osteocyte within a lacuna. |
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In the center of each osteon is a passageway called the Haversian canal. Within this canal are the blood vessels that supply nutrients to the osteocytes by way of the canaliculi. |
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Radiating out from the Haversian canal, like spokes on a wheel, are the canaliculi. |
This model shows the microscopic structure of bone.
A- Compact Bone
B - Perforating (Volkmann's) canal
C - Periosteum
D - Spongy bone
E - Haversian System (Osteon)
Osteocytes are not the only types of cells found in bone:
Osteoblast: Cells that lay down new bone.
Osteoclast: Cells that destroy old bone so that growth can occur. Osteoclasts also begin to destroy bone when the body is deficient of calcium, as well as when bone is not used.
Other terms to know:
Spongy bone: Spongy bone has no Haversian systems. Instead the arrangement is like a web (Trabeculae).
Diaphysis: The shaft of a long bone.
Epiphysis: The end or head of a long bone.
Periosteum: a covering over the surface of the bone. Made of dense connective tissue.
Articular Cartilage: Hyaline cartilage which covers the epiphyseal surface where a bone form a joint with another bone. Epiphyseal surfaces which are not part of an articulating surface are covered by the periosteum.
The markings on bones (such as tuberosities, lines, crests, and spines) serve as sites of attachment for muscles and/or ligaments.
Openings in bones (such as foramen, fossa, fissures, etc.) serve as passageways for blood vessels and/or nerves.
Projections on bones (like heads and condyles) take part in forming joints.
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