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Bone Function and Classification Structure of a Long Bone Pg. 116 - 121. September 24, 2012. Bone Functions. Support Supports and anchors all soft organs Protection Protection of soft body organs Movement Skeletal muscles use the bones as levers to move the body and its parts Storage
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Bone Function and ClassificationStructure of a Long BonePg. 116 - 121 September 24, 2012
Bone Functions • Support • Supports and anchors all soft organs • Protection • Protection of soft body organs • Movement • Skeletal muscles use the bones as levers to move the body and its parts • Storage • Fat is stored in the internal cavities of bones • Bone itself serves as a storehouse for calcium, phosphorus, and other minerals • Blood cell formation • Hematopoiesis – formation of blood cells from the bone marrow cavities of certain bones
What type of tissue is bone? • Connective! Bone is also called OSSEOUS tissue. How many bones are in the human body? • 206
Classification of Bones • Two basic types • Compact bone • Dense, looks smooth and homogenous • Spongy bone • Small, needlelike pieces of bone with lots of open space
What’s the smallest bone in the body? • Pisiform bone of the wrist – it is the size and shape of a PEA! • What’s the largest bone in the body? • Femur (thigh bone) – it is almost 2 feed long and has a large, ball-shaped head.
Classification…Shape • Long bones – longer than they are wide • Shaft with heads at ends, mostly compact bone • All bones of the limbs except wrist and ankle bones • Short bones – cube-shaped, mostly spongy bone • Wrist and ankle bones • Sesamoid bones (form inside of tendons, like the patella) are a special type of short bone • Flat bones – thin, flattened, usually curved • 2 thin layers of compact bone sandwiching spongy bone • Most bones of the skull, ribs, and sternum • Irregular bones – do not fit other 3 categories • Vertebrae, hip bones
Structure of a Long Bone – Gross Anatomy • Diaphysis – shaft of the bone, makes up most of the length • Periosteum – covers and protects diaphysis • Epiphyses – ends of the long bone • Articular cartilage – covers epiphyses • Epiphyseal line – thin line of bony tissue between the epiphysis and the diaphysis • Remnant of epiphyseal plate, a flat plate of hyaline cartilage that is seen in young, growing bones
Structure of a Long Bone – Gross Anatomy • The cavity of the diaphysis is used for storage of adipose tissue. • It is called the yellow marrow cavity • Red marrow is found in this cavity in infants – it makes blood cells • In adults, red marrow is found in cavities of spongy bone in flat bones and in the epiphyses of some long bones
Structure of a Long Bone – Gross Anatomy • Bones are not smooth – if you look closely, you will see several grooves and indentations • These are places where muscles, tendons, and ligaments attach to the bones • Include processes and depressions • Tuberosity, crest, trochanter, line, tubercle, epicondyle, spine, process, head, facet, condyle, ramus, meatus, sinus, fossa, groove, fissure, and foramen
Structure of a Long Bone – Microscopic Anatomy • Osteocytes are mature bone cells found within lacunae, which are arranged in concentric circles called lamellae around central (Haversian) canals • An osteon, or Haversian system, consists of the central canal and matrix rings • Run lengthwise through the bone, carrying blood vessels and nerves to all areas of the bone • Canaliculi are tiny canals that radiate from central canals to all lacunae – these connect all bone cells to the nutrient supply through the hard bone • Because of this, bone injuries heal quickly and efficiently • Perforating (Volkmann’s) canals run into the compact bone at right angles to the shaft and provide a communication pathway from the outside of the bone to the inside
Bone is one of the hardest materials in the body • Lightweight • Resists tension and other forces • Extremely strong while exceptionally simple • Calcium salts give hardness whereas organic parts provide flexibility and strength