Bone - Overview

• Functions of bones


  • Support
  • Protection
  • Allow movement
  • Storage
  • Blood cell formation
• Compact bone


  • Dense and looks smooth and homogenous
• Spongy bone


  • Has a spiky, open appearance like sponge
• Types of bones by shape

  • Long bones
  • Flat bones
  • Short bones
  • Irregular bones
• Long bones


  Typically longer than they are wide, have a shaft with enlarged ends, mostly compact bone but also contain spongy bone at the ends
• Flat bones


  Thin, flattened, and usually curved, have two thin layers of compact bone sandwiching a layer of spongy bone between them
• Short bones


  Generally cube-shaped and contain mostly spongy bone with an outer layer of compact bone
• Irregular bones


  Bones that do not fit one of the preceding categories, the vertebrae are an example
• Structures of a long bone

  • Diaphysis
  • Periosteum
  • Perforating fibers
  • Epiphyses
  • Articular cartilage
  • Epiphyseal line
  • Epiphyseal plate
  • Endosteum
  • Medullary cavity
  • Bone markings
• Diaphysis


  The shaft of the bone, composed of compact bone
• Periosteum


  A connective tissue membrane that covers and protects the diaphysis
• Perforating fibers


  Connective tissue fibers that secure the periosteum to the underlying bone
• Epiphyses


  The ends of long bones, each consisting of a thin layer of compact bone enclosing an area filled with spongy bone
• Articular cartilage


  A glassy hyaline cartilage that provides a smooth surface to decrease friction at the joint
• Epiphyseal line


  A thin line of bony tissue spanning the epiphyses, a remnant of the epiphyseal plate
• Epiphyseal plate


  A flat plate of hyaline cartilage in young, growing bone that causes lengthwise growth
• Endosteum


  A delicate connective tissue that covers the inner bony surface of the shaft
• Medullary cavity


  The cavity of the shaft, a storage area for red marrow in infants and yellow marrow in adults
• Bone markings


  Reveal where muscles, tendons, ligaments, blood vessels, and nerves attach
• Microscopic anatomy of compact bone

  • Osteocytes
  • Lacunae
  • Lamellae
  • Central canals
  • Osteons
  • Canaliculi
  • Perforating canals
• Bone is one of the hardest materials in the body, and although relatively light in weight, it has a remarkable ability to resist tension and other forces acting on it
• The calcium salts deposited in the matrix give bone its hardness, which resists compression. The organic parts (especially the collagen fibers) provide for bone's flexibility and great tensile strength (ability to be stretched without breaking)