skeletal system

• Bones (osseous tissue, is a hard, dense connective tissue)
• Joints (where two or more bones meet to create mobility)
• Tendons (muscle-bone)
• Ligament (bone-bone)
• Cartilage (semi-rigid connective tissue, provides flexibility)
• functions of skeletal system

  support

  protection

  storage of mineral

  helping in movement

  chemical storage

  production of red blood cells
• Compact Bone

  – denser, stronger of the two types

  – found under the periosteum and in the diaphyses of long bones

  – microscopic structural unit: osteon/Haversian system
• Spongy bone (cancellous)

  – has open spaces and supports shifts in weight distribution

  – consists of plates (trabeculae) and bars of bone adjacent to small, irregular cavities that contain red bone marrow
• epiphyseal plate (growth plate) layer of hyaline (transparent) cartilage in a growing bone = When the bone stops growing in early adulthood (approximately 18–21 years) =cartilage to osseous tissue = epiphyseal line
• medullary cavity has a delicate membranous lining called the endosteum (end- = “inside”; oste- = “bone”), where bone growth, repair, and remodeling occur
• articulation - where two bone surfaces come together (articulus = “joint”)
• projection - area of a bone that projects above the surface of the bone; attachment points for tendons and ligaments; their size and shape is an indication of the forces exerted through the attachment to the bone
• hole - opening or groove in the bone that allows blood vessels and nerves to enter the bone
• tuberosity - large, rounded projection, may be roughened
• crest - narrow ridge of bone usually prominent
• trochanter - very large, blunt irregular shaped process
• line - narrow ridge of bone, less prominent than a crest
• head - bony expansion carried on a narrow neck
• facet - smooth nearly flat articular surface
• osteogenic (osteoprogenitor) cells are undifferentiated with high mitotic activity found in periosteum and the endosteum.
• Osteoblast - Bone forming cells (for ossification)
• Osteocytes - Mature bone cells
• Osteoclast - Bone destroying cells (for bone resorption)
• Ossification – process of bone formation
• Bone Resorption – process of bone destruction
• 2 main divisions of bones

  • axial (80)
  • appendicular (126)
• AXIAL SKELETON - Make up the longitudinal axis of the body
• AXIAL SKELETON Includes bones of the:

  • Skull

  • Vertebral Column

  • Thoracic Cage
• Appendicular Skeleton

  • Make up the bones of the limbs & Bones that connect to the:

  o Pectoral Girdle (shoulder girdle)

  o Pelvic Girdle (hip girdle)
• Vertebral Bones

  • Cervical (7 bones)

  • Thoracic (12 bones)

  • Lumbar (5 bones)

  • Sacrum (5 fused bones)

  • Coccyx (4 fused bones)
• Articulations = joints

  hold bones together while usually allowing some movement
• Functional: degree of movement

  • synarthroses - immovable
  • amphiarthroses - slightly movable
  • diarthroses - freely movable
• Fibrous Joint – articular surface of both bones joined by fibrous connective tissue; immovable joint
• Cartilaginous Joints – articular surface joined by some kind of cartilage (eg. fibrous or hyaline) ; slightly movable
• Synovial Joints – articulation is surrounded by joint capsule and synovial membrane joint capsule articular cartilage joint cavity synovial membrane synovial fluid periosteum; freely movable
• sutures – only in skull
• gomphoses -teeth in socket
• syndesmoses - fibrous bands between two bones - distal tibiofibular joint
• symphyses -fibrocartilage pad or disc – symphysis pubis – intervertebral discs
• synchondroses -hyaline cartilage joins two bones

  – epiphyseal discs;

  – temporary -costal cartilage between ribs and sternum