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25 Cards in this Set
- Front
- Back
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What are three types of bone?
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Woven, cortical, trabecular.
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Where is woven bone found?
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The bones of fetuses, young children (< 4 y.o.), and initial stages of bone repair.
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What is so special about woven bone structurally?
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It has coarse collagen fibers which are oriented randomly (ie. not due to experienced stress loading)
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What are some synonyms for cortical bone?
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Compact, dense.
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Where is compact bone found?
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The outer shell or cortex of bones.
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What is cortical bone composed of?
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Lamellar bone arranged in osteons.
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How is lamellar bone different than woven bone?
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Lamellar bone's collagen fibers are oriented in parallel concentric sheets making it much stronger. It also contains fewer osteocytes.
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What is an osteon?
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Aka Haversian canal. It is a cylindrical unit usually oriented in the long axis with about 4-20 concentric lamellae surrounding a central Haversian canal containing small blood vessels and nerves.
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Where are the osteocytes found in lamellar bone?
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Found in lacunae which are arranged circumferentially around the central canal.
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In relation to osteons what are canaliculi?
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Fine passages through the lamellae which contain the slender osteocyte processes (allow for cellular communication)
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What are Volkman canals?
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Transverse passages connecting neighboring Haversian canals and penetrate from the periosteal surface to carry blood vessels from one osteon to another.
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What are some synonyms for trabecular bone?
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Spongy, cancellous.
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What is trabecular bone composed of ?
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Lamellar or woven bone (in the young or healing) arranged into interconnecting trabeculae that forms a three dimensional latticework.
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Where is trabecular bone found?
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In the internal areas of bone.
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How does remodelling occur in trabecular bone?
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Remodels along internal lines of stress with osteoblasts laying down bone on one part of trabecula while osteoclasts resorb another part.
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What are some functions of trabecular bone?
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Strength (its latticework adapts to experienced stresses), provides a large surface area for marrow metabolic activities, protects the marrow cells.
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What is the diaphysis?
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It is the main or mid section(shaft) of a long bone.
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What is the diaphysis composed of?
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An outer layer of cortical bone surrounding a medullary cavity of bone marrow and adipose tissue.
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What is the metaphysis?
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The portion of long bone between the epiphyses and the diaphysis. Histologically it is the zone of ossification containing the primary and secondary spongiosa. In adults it may refer to the bone ends.
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What is the metaphysis composed of?
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Primary spongiosa and secondary spongiosa. Where primary spongy bone is formed and resorption of calcified cartilage with secondary remodelling of spongy bone are performed respectively.
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What is the periosteum?
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A tough fibrous, highly specialized connective tissue covering the outer surface of bones (except where there are joints)
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What is the outer layer of the periosteum composed of?
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Dense irregular connective tissue consisting mostly of fibroblasts with type I collagen fibers and a small proportion of elastic fibers. Also contains many large blood vessels, nerves and lymphatics.
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What is the inner layer (cambium) composed of?
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Layer of loose richly vascularized connective tissue with osteogenic cells and osteoblasts in direct contact with the bone. Blood vessels of small caliber give rise to branches that supply Volkman and Haversian canals.
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How is the periosteum attached to the bone?
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Bundles of collagen (Sharpey) fibers originating in the outer layer penetrate underlying bone at regular intervals.
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Where are Sharpey fibers especially prominent?
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Attachment sites of tendons and ligaments.
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