Classification of Bones

• Bones are classified into five (5)

  • Long bone
  • Short bone
  • Flat bone
  • Irregular bone
  • Sesamoid bone
• Long bone

  • is cylindrical in shape, being longer than it is wide.
  • these are found only in the appendicular skeleton.
  • found in the arms, legs, finger, and toes.
  • they function as levers; they move when muscles contract.
• Compact bone (cortex)


  a hard and dense bone tissue that makes up the outer shell (diaphysis) of most bones.
• Body (shaft)


  contains a thicker layer of compact bone that help resist the stress of the weight placed on them.
• Spongy (Cancellous) bone


  highly porous and usually contains red bone marrow
• Medullary cavity


  the hollow portion of the bone that usually contains fatty yellow marrow.
• Periosteum


  a dense fibrous membrane that covers bone except at the articulating surfaces.

  it is essential for bone growth, repair, and nutrition.
• Articular (Hyaline) cartilage


  covers the articulating surfaces.

  reduces friction and acts as a shock absorber.
• Hyaline (gristle)


  means glassy or clear, a common type of cartilage or connecting tissue
• Nutrient artery


  passes obliquely though the compact bone via a nutrient foramen into the medullary cavity.
• Short bones


  are roughly cuboidal and are found only in the wrists and ankles.

  consists mainly of cancellous tissue with a thin outer covering of compact bone.
• examples of short bones:

  eight (8) carpal bones of each wrist;

  seven (7) tarsal bones of each foot
• Flat bones


  consist of two plates of compact bone with cancellous bone and marrow between them.

  serves as points of attachment for muscles.
• Flat bones example

  calvaria (skull cap)

  sternum

  ribs

  scapulae
• Irregular bones


  bones that have peculiar shapes

  examples: vertebrae, facial bones, base of cranium, pelvic bones
• diploe


  the narrow space between the inner and the outer table of flat bones within the cranium