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The skeletal system
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The skeletal system


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The Skeletal System......Bones......Joints.....Joints Types......Bone Structure.

The Skeletal System......Bones......Joints.....Joints Types......Bone Structure.

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  • 1. By Muhammad Iqbal Khan SS Biology Email ID: 0923135448175 The Skeletal System
  • 2. Function  Support  Internal framework of body  Ex: Legs support body trunk, rib cage supports chest wall  Protection  Protects soft body organs (skull protects brain, ribs protect heart and lungs, etc)  Movement*  Muscles use bones as levers to move body  NOT a function skeletal system can do on it’s own  Storage  Fat storage  In yellow marrow  Mineral storage  Calcium, phosphorus, and others.  Blood cell formation  Hematopoeisis  Occurs in bone marrow of long bones
  • 3. Bones 206 bones in the adult skeleton Two types of bone Compact bone Homogeneous appearance Dense, looks smooth Spongy bone Small needle-like pieces Lots of open spaces (Looks like a sponge, hence the name)
  • 4. Bone Classification Long Bones Longer than wide Contain shaft with head at each end Mostly compact bone Limbs (not ankle or wrist bones) Short Bones Cube-shaped Mostly spongy bone Wrist and ankle bones Patella (kneecap) Flat Bones Thin, flat, usually curved Two layers of compact bone with spongy bone in between Skull, ribs, breastbone Irregular Bones Don’t fit into the other categories Vertebrae, hip bones
  • 5. Bone Classification
  • 6. Long Bone Anatomy Diaphysis Shaft Made of compact bone Epiphyses Ends of long bone Made of compact bone surrounding spongy bone Covered with articular cartilage Smooth, glassy, decreases friction at joints
  • 7. Long Bone Anatomy Epiphyseal Line Line of bone tissue that looks different from rest of bone Remnant of epiphyseal plate Hyaline cartilage Causes long bones to grow lengthwise
  • 8. Long Bone Anatomy Periosteum Outer covering of shaft Like “skin” on chicken bone Sharpey’s fibers Attach periosteum to bone Arteries Supply nutrients to bone cells
  • 9. Long Bone Anatomy Medullary Cavity In shaft Contains yellow marrow (adipose) in adults Contains red marrow in infants (for blood cell formation)
  • 10. Microscopic Anatomy of Bone Osteon (Haversian system) A “unit” of bone Central (Haversian) canal Opening in center of osteon Contains blood vessels Perforating (Volkman’s) canal Perpendicular to central canal Contains blood vessels and nerves
  • 11. Microscopic Anatomy of Bone
  • 12. Microscopic Anatomy of Bone Lacunae Cavities that contain osteocytes (bone cells) Arranged in concentric rings (like tree rings) Lamellae Rings around the central canal Where the lacunae can be found
  • 13. Microscopic Anatomy of Bone Canaliculi Tiny canals Radiate from central canal to lacunae Transport nutrients to bone cells
  • 14. Other Facts Bone is one of the hardest parts of the body Very lightweight Can resist tension Calcium salts make it hard Collagen fibers make it strong and flexible
  • 15. Bone Formation In embryos… Skeleton made of hyaline cartilage Gets replaced by bone with age Cartilage remains in a few places… Bridge of nose Parts of ribs Joints
  • 16. Bone Growth Epiphyseal plates allow for growth of long bone during childhood New cartilage is continuously formed Older cartilage becomes ossified Cartilage is broken down Bone replaces cartilage Bones remodeled, lengthened until growth stops Bones change shape somewhat Bones grow in width
  • 17. Long Bone Growth
  • 18. Long Bone Growth
  • 19. Types of Bone Cells Osteocyte Mature bone cell Osteoblast “Bone builders” Osteoclast “Bone destroyers” Break down bone matrix to remodel and/or release calcium
  • 20. Bone Remodeling Bone remodeling is done by osteoblasts and osteoclasts Essential for bones to keep normal proportions and strength Bones get larger/thicker when… Large muscles are attached to them Need more bone to attach the large muscle to Bones get smaller/weaker when… Physical inactivity Non-use of musclesatrophy Small muscles don’t need large bones to attach to  Bones remodeled to become smaller
  • 21. Fractures A break in a bone Types of Fractures Simple (closed) fracture Bone breaks cleanly, does not penetrate skin Compound (open) Fracture When bone ends penetrate through skin Treated by reduction and immobilization Realignment of bone ends
  • 22. Common Fractures
  • 23. Bone Repair Hematoma forms Blood vessels rupture when bone breaks Blood filled swelling Cells without nutrients die Fibrocartilage callus forms Made of connective tissue Splints the break Phagocytes dispose of dead tissue Bony callus forms Osteoblasts/clasts move in, create callus of spongy bone Remodeling Osteoblasts/clasts remodel in response to stress on the bone Helps strengthen bone Creates a permanent “patch” at the site Often, a healed fracture can be stronger than the rest of the bone
  • 24. Bone Repair
  • 25. Axial Skeleton Makes up longitudinal part of the body Three parts Skull Vertebral column Bony thorax **Note: notes on specific bones are not included. Make sure you are using your textbook to help identify shapes/functions of bones!!
  • 26. Axial Skeleton **Shown in green
  • 27. Skull Formed by two sets of bones Cranium Encloses/protects brain Facial bones Holds eyes forward (anterior position) Allow facial muscles to show feelings Sutures Interlocking, immovable joints holding most skullbones together Mandible-only freely movable bone in skull
  • 28. Skull
  • 29. Skull
  • 30. Paranasal Sinuses Hollow portions of bone around nasal cavity Named for bones they are found in Lighten skull Amplify sounds when speaking/ give resonance
  • 31. Fetal Skull Large in comparison to body length of infant Contains fontanelles Soft fibrous membranes connecting cranial bones “Soft Spots” Usually convert to bone around 24 months after birth
  • 32. The Vertebral Column Vertebrae named for their location 7 cervical vertebrae  C1 = Atlas  C2 = Axis 12 thoracic vertebrae 5 lumbar vertebrae Sacrum  5 fused vertebrae Coccyx  4 fused vertebrae Vertebrae separated by fibrocartilage discs Cushions/absorbs shock
  • 33. Vertebrae Structure
  • 34. Regional Characteristics
  • 35. Regional Characteristics
  • 36. Bony Thorax Forms a cage to protect organs Three parts Sternum  Flat bone  3 fused bones  Manubrium  Body  Xyphoid process  Attached to first 7 pr of ribs Rib Cage  12 pairs  True Ribs= 7 pr  False Ribs = 5 pr  Floating Ribs = 2 pr Thoracic vertebrae
  • 37. Appendicular Skeleton Limbs (appendages) Pectoral girdle Pelvic girdle **shown in yellow
  • 38. Pectoral Girdle (shoulder) Two bones Clavicle-collarbone Scapula-shoulder blade
  • 39. Upper Limb (arm) Arm bone- humerus Forearm bones- Radius (thumb side) Ulna Hand bones Carpals-wrist Metacarpals-palm Phalanges-fingers
  • 40. Pelvic Girdle (hip bones) Three pairs of fused bones Ilium Ischium Pubic bone Carries total weight of upper body Protects Reproductive organs Bladder Part of large intestine
  • 41. Gender Differences in Pelvis Female inlet larger/more circular Female pelvis is shallower, bones lighter/thinner Female hip bones flare wider Female sacrum is shorter/less curved Female pubic arch is more rounded/angle is greater
  • 42. Lower Limb (leg) Thigh bone-femur Two leg bones Tibia (larger, medial bone) Fibula (smaller, lateral bone) Foot Tarsals-ankle Metatarsals-sole Phalanges-toes
  • 43. Joints Articulations of bones Functions Hold bones together Mobility Classified by structure/function **we’ll use structural classification Fibrous joints Immovable EX: sutures of skull Cartilaginous joints Immovable OR slightly movable EX:Pubic symphysis and Vertebrae Synovial joints Freely movable **Be familiar with types of synovial joints (illustrations to follow)
  • 44. Synovial Joints Articulating bones separated by joint cavity Articular cartilage covers bone ends Joint surfaces enclosed by fibrous capsule Cavity contains synovial fluid Ligaments help reinforce the joint Associated Joint Structures Bursae  Flat fibrous sacs  Lined with synovial membrane  Contains synovial fluid  Common where ligaments, muscles, skin, tendons rub together Tendon sheath  Elongated bursa wrapping around a tendon that deals with lots of friction  Like a bun around hot dog
  • 45. Synovial Joints
  • 46. Types of Synovial Joints by Shape
  • 47. Types of Synovial Joints by Shape