Bone Function and Classification Structure of a Long Bone Pg. 116 - 121

1. Bone Function and ClassificationStructure of a Long BonePg. 116 - 121 September 24, 2012

2. 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

3. What type of tissue is bone? • Connective! Bone is also called OSSEOUS tissue. How many bones are in the human body? • 206

4. 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

5. 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.

6. 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

7. 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

8. 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

9. 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

10. 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

11. 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