skeletal system

• Major functions of the skeletal system

  • Supports our body
  • Allows movement
  • Protection of organs
  • Stores minerals
  • Makes new blood cells
• Components of the skeletal system

  • Bones
  • Cartilage
  • Joints
  • Ligaments (join bone to bone)

  
• Adult skeleton has 206 bones
• Bone tissue components

  • Cells
  • Bone matrix

  
• Osteoblasts

  Bone forming cells

  
• Osteoclasts

  Bone-destroying cells
• Osteocytes

  Bone-maintaining cells

  
• Bone is constantly remodelled i.e. bone is being broken down and rebuilt. This is important in the homeostasis of the minerals stored in bone

  
• Types of bone tissue

  • Compact bone
  • Spongy bone

  
• Compact bone is solid and homogeneous

  
• Spongy bone is sponge-like in shape with many open spaces
• Compact bone

  Stronger than spongy bone

  
• Advantage of spongy bone

  Lighter weight
• Osteon

  Functional unit of bone containing a central canal and rings of bone matrix

  
• Parts of an osteon

  • Central canal-for nerves & blood vessels
  • Perforating canal-for nerves & blood vessels
  • Lamellae-rings around central canal
• More parts of an osteon

  • Lacunae- cavities containing bone cells
  • Canaliculi – tiny canals going from central canal to lacunae carry nutrients

  
• Anatomy of a long bone

  • Diaphysis-Shaft-Compact bone
  • Epiphysis-Ends of the bone-Mainly spongy bone
  • Periosteum –fibrous connective tissue layer
  • Medullary cavity – contains bone marrow

  
• Axial Skeleton

  Comprised of skull, vertebrae and rib cage

  
• Bones of the Skull

  • Parietal bone
  • Occipital bone
  • Frontal bone
  • Temporal bone
  • Mandible

  
• Vertebral column

  33 vertebrae named according to their location: 7 Cervical, 12 Thoracic, 5 Lumbar, 5 Sacral, 4 Coccyx

  
• Vertebrae have cartilage discs in between them

  
• Vertebrae

  • Have a vertebral foramen, a main body and a number of bony processes
  • Depending on their location, can have quite different shapes

  
• Ribs

  • True ribs (pairs 1-7)
  • False ribs (pairs 8-12)
  • Floating ribs (also false, pairs 11-12)
• The job of the rib cage is to protect the thoracic organs
• Appendicular Skeleton

  Comprised of limbs, pectoral and pelvic girdle

  
• Pectoral girdle

  • 2 x clavicle (collarbone)
  • 2 x scapula (shoulder blade)
• Pelvic girdle

  • 2 coxal bones (formed from ilium, ischium & pubis)

  
• The two largest tarsals are the talus and calcaneus
• Joints

  Hold bones together where they meet and allow us to move
• Joint classification by structure

  • Fibrous
  • Cartilaginous
  • Synovial
• Joint classification by function

  • Immovable/slightly movable
  • Freely movable
• Connective tissues of joints

  • Ligaments
  • Tendons
  • Cartilage
• Osteoporosis

  Imbalance between bone formation and bone resorption, occurs 2.5 times more frequently in women
• Risk factors for osteoporosis

  • Age
  • Vitamin D or calcium deficiency
  • Malabsorption
  • Smoking
  • Excessive alcohol
  • Underweight/inactive
  • Medical conditions
  • Certain medicines