Skeletal System

• Long bones


  are longer and wide. Most of the bones of the upper and lower limbs
• Short bones


  are approximately as broad as they are long, such as the bones of the wrist and ankle.
• Flat bones


  have relatively thin, flattened shape. examples: skull, bones, ribs, scapulae, and the sternum.
• Irregular bones


  include the vertebrae and facial bone, with shapes that don't fit readily into other 3 categories
• Diaphysis


  The shaft of the long bone
• Epiphysis


  The two expanded ends of a bone.
• Articular Cartilage


  covers the ends of the epiphysis where the bone articulates with other bone.
• Epiphyseal plate/growth plate


  A long bone that is still growing..
• Large medullar cavity


  Bones that contain cavities
• Marrow


  The soft tissue in the medullar cavities of the bone
• Red Marrow


  consists of blood-forming cells and the only site of blood formation in cells
• Yellow marrow


  consists mostly of fat.
• Periosteum


  The dense connective tissue that covers most of the outer surface of the bone.
• Endosteum


  contains blood vessels with a thinner connective tissue membrane.
• Osteoblasts


  which function in the formation of bone, as well as in the repair and remodelling of the bone.
• Lamellae


  bone is formed in thin sheets of extracellular matrix.
• Osteocytes


  are bone cells located between the lamellae
• Lacunae


  the osteocytes are located within spaces
• Canaliculi


  Cell processes extends from the osteocytes across the cellular matrix of the lamellae with tiny canals
• Compact bone


  Mostly solid matrix and cells; forms most of the diaphysis of long bone.
• Haversian canal


  sets of concentric rings, with each set sorrounding.
• Haversian system 


  each central canal, with lamellae and osteocytes surrounding it.
• Cancellous/Trabecular/Spongy bone


  consists of lacy network of bone with many small, marrow-filled spaces
• Trabeculae


  Delicate interconnecting rods or plates of bones
• Ossification


  the formation of bone by osteoblasts
• Intramembranous ossification


  occurs when osteoblasts begin to produce bone.

  
  

  occurs in the early embryo to create flat bones such as the skull and clavicle.
• Endochondral ossification


  is the process by which growing cartilage is systematically replaced by bone to form the growing skeleton.

  
  

  forms ossified tissue to replace areas of cartilage.
• Zone of reserve or resting cartilage


  the chondrocytes exhibit no division or active matrix production
• Zone of proliferation


  The chondrocytes undergo cell division and arrange themselves in distinct columns
• Zone of Hypertrophy


  the chondrocytes enlarge and compress the cartilage matrix surrounding them
• Zone of Calcification


  the enlarged cells begin to degenerate as the matrix become calcified
• Zone of Resorption or Ossification


  The cavities left by dead chondrocytes are invaded by blood vessels
• Articulation/Joint


  a place where two bones come together
• Synarthrosis


  non-movable joint; skull sutures, articulations of bony sackets and teeth in facial skeleton
• Amphiarthrosis


  slightly movable joint; distal joint between the tibia and the fibula and the pubic symphysis
• Diarthrosis


  Freely movable joint; elbow, shoulder, ankle
• Fibrous joints


  consists of two bones that are united by fibrous tissue and that exhibit little to no movement.
• Sutures


  are fibrous joints between the bones of the skull
• Fontanels


  Some parts of the sutures are quite wide, called as soft spot
• Syndesmoses


  are fibrous joints in which the bones are separated by some distance and are held together by ligaments