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SKELETAL SYSTEM

SKELETAL SYSTEM. SKELETAL SYSTEM FUNCTIONS. Support (Primary function) Movement (Passive) Protection of Vital Organs Mineral Storage Blood Cell Formation (Hematopoiesis or Hemopoiesis). OSSEOUS C.T. Compact (dense) Bone Hard & heavy Forms surface & diaphysis Osteons = building blocks

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SKELETAL SYSTEM

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  1. SKELETAL SYSTEM

  2. SKELETAL SYSTEM FUNCTIONS • Support (Primary function) • Movement (Passive) • Protection of Vital Organs • Mineral Storage • Blood Cell Formation (Hematopoiesis or Hemopoiesis)

  3. OSSEOUS C.T. • Compact (dense) Bone • Hard & heavy • Forms surface & diaphysis • Osteons = building blocks • Cancellous (spongy) Bone • Lightweight • Fills epiphyses, Contains red marrow • Trabeculae = building blocks • Matrix • Mineral Salts (hardness) • Collagen (strong & flexible)

  4. Bone Cells • Osteoblasts – Secrete to form bone • Osteocytes • Mature bone cells • “Trapped” osteoblasts • Osteoclasts – destroy bone • Enzymes digest protein • Acids dissolve minerals • Forms Marrow Cavity; Involved in Remodeling

  5. Osteoblasts & Osteocytes

  6. Osteoclast

  7. SKELETAL DIVISIONS • Axial • Appendicular

  8. Classification: Shape & Location • Long • Short • Flat • Irregular • Sesamoid (develop in tendons; patella) • Sutural (between cranial bones)

  9. LONG BONE ANATOMY • Diaphysis = shaft made of compact bone • Epiphyses = ends filled with spongy bone containing red marrow • Articular cartilage covers epiphyses • Epiphyseal line indicates earlier location of epiphyseal (growth) plate

  10. LONG BONE ANATOMY • Periosteum is C.T. covering bone • Nutrient Foramina – holes allowing for penetration of arteries • Medullary cavity contains yellow marrow • Endosteum is C.T. lining medullary cavity

  11. BONE DEVELOPMENT • Ossification = replacement of other connective tissue with bone • Begins during the 2nd month of gestation • Size increases until late teens (females) to mid-twenties (males) • Ossification processes include: • Intramembranous bone formation • Endochondral bone formation

  12. INTRAMEMBRANOUS OSSIFICATION • Occurs in flat bones of skull, clavicles, mandible • Begins with fibrous C.T. membrane • Membrane calcifies & ossifies into bone • Fontanels • “Soft spot”, not yet ossified • Allows for birth & brain growth

  13. ENDOCHONDRAL OSSIFICATION • Occurs in remainder of skeleton • Begins with hyaline cartilage model • Cartilage is replaced by bony tissue • Steps include: • Bone collar forms • Cartilage in shaft calcifies • Primary Ossification center forms in shaft • Secondary Ossification centers in epiphyses

  14. Formation of Bone Collar & Primary Ossification Center

  15. Formation of Secondary Ossification Centers

  16. Epiphyseal Plates & Articular Cartilage

  17. APPOSITIONAL GROWTH • Bone Widens • Osteoclasts enlarge medullary cavity • Osteoblasts add bone to surface of diaphysis

  18. BONE REMODELING • Replacement of old bone with new bone • Involves resorption (osteoclasts) & deposition (osteoblasts) • Allows for growth • Removes injured bone • Alters bone shape in response to stress

  19. FRACTURES AND THEIR REPAIR • Definition: Any break in a bone • Repair may take months • Types include • Simple (skin not broken) • Compound (bone protrudes through skin) • Greenstick (shaft bent/broken) • Spiral (twisting force, ragged break) • Comminuted (shattered into fragments)

  20. STEPS IN FRACTURE REPAIR • Broken blood vessels form a hematoma (blood clot) • C.T. and Capillaries invade site; C.T. cells form fibrocartilage callus • Bony callus of spongy bone replaces fibrocartilage callus • Bony callus is remodeled

  21. BONES AS LEVERS • Lever: A rigid rod that moves about a fixed point • Fulcrum: The fixed point around which a lever moves (joints) • Forces: Act to move levers at two points • Resistance: Force to be overcome • Effort or Work: Force required to overcome resistance; supplied by skeletal muscles

  22. CLASSES OF LEVERS • First Class: The fulcrum is between the effort/force and the resistance • Seesaw • Tilting head backward

  23. R R R R R R R F E E E E E E E FIRST CLASS LEVER

  24. CLASSES OF LEVERS CONTINUED • Second Class: Resistance is between the fulcrum and the effort/force • Wheelbarrow • Rising up on one’s toes

  25. R R R R R R R R F E E E E E E E E SECOND CLASS LEVER

  26. CLASSES OF LEVERS CONTINUED • Third Class: The effort/force is between the fulcrum and the resistance • Most common type in the human body • Flexing the elbow

  27. R R R R R R R R F E E E E E E E E THIRD CLASS LEVER

  28. CLASSIFICATION OF JOINTS • Structural • Based on what tissues or structures are found between the bones • Fibrous, Cartilagenous, Synovial • Functional • Based on amount of movement (& amount of movement is determined by structures found between bones) • Freely movable, Slightly movable, Immovable

  29. ARTICULATIONS: CLASSIFICATION BY STRUCTURE

  30. ARTICULATIONS: CLASSIFICATION BY FUNCTION

  31. Pubic symphysis Functional: AmphiarthrosisStructural: Cartilagenous Knee Functional: DiarthrosisStructural: Synovial Sutures Functional: SynarthrosisStructural: Fibrous ARTICULATIONS: EXAMPLES

  32. STRUCTURE OF A SYNOVIAL JOINT • Articular cartilage – covers bone ends • Synovial membrane – lines joint capsule • Synovial fluid – lubricates & nourishes cartilage • Synovial cavity – space between the bones • Joint capsule – fibrous C.T. • Ligaments – reinforce joint • Bursae – synovial sacs at other sites of friction

  33. TYPES OF SYNOVIAL JOINTS Classified based on shape of articular surfaces • Gliding (plane) • Hinge • Pivot • Ellipsoidal (condyloid) • Saddle • Ball-and-socket

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