The Skeleton and Muscles

Functions of the skeleton
1. Support: skeleton supports the body and keeps it upright
2. Protection: skull protects the brain, backbone protects spinal cord, ribs protect the lungs
3. Manufacture of blood cells: red cells, white cells and platelets are made in bone marrow of the long bones
4. Movement: bones provide rigid levers against which the muscles can pull
The Axial Skeleton
1. Composed of the skull (cranium), facial bones, vertebral column (spine), rib cage and sternum (breastbone)
2. Spine
  1. A pad of fluid enclosed by cartilage, called a disk act as shock absorbers and protect the vertebrae from rubbing each other
The Appendicular Skeleton
1. Consists of the pectoral and pelvic girdles, and their attached limbs
2. Pectoral (shoulder) girdle
  1. Consists of scapula (shoulder blade) and clavicle (collar bone)
  2. Function is to give upper body mobility and strength
3. Pelvic (hip) girdle
  1. Consists of the pelvis (made up of three fused bones called innominate bones)
  2. Gives strength and support to the body and allows mobility of lower limbs
Structure of a Long Bone
1. Compact Bone
  1. The inorganic material gives strength to the bone
  2. The organic material gives the bone flexibility
  3. Contains blood vessels and nerve fibres
2. Medullary Cavity
  1. Contains a soft material called bone marrow
  2. Red marrow is active in making blood cells
  3. Yellow marrow is inactive and contains numerous fat-storage cells
    1. Can convert to red marrow if needed
3. Spongy Bone
  1. Consists of a mixture of compact bone with pockets of bone marrow
  2. Function is to give strength and rigidity to bones without making them too heavy
4. Cartilage
  1. It protects the end of long bones and acts as a shock absorber
  2. Made of collagen
Bone Growth
1. Osteoblasts produce and lay down new bone
2. Osteoclasts digest and remove old bone
3. Cartilage slowly converted to bone (ossification)
4. In growth plate, osteoblasts form bone matrix to extend the length of bones
Joints
1. A joint is where two or more bone meet
2. Immovable Joints: allow no movement between the bones. Their function is strength and protection
3. Slightly Movable Joints: allow a small amount of movement between bones. e.g. joints between vertebrae
4. Freely Movable Joints: contain synovial fluid in joint cavity which allows greater friction-free movement
  1. Hinge Joints: allow movement in one direction only
  2. Ball and Socket: allow movement in all direction
Muscles
1. Cardiac muscle: located in the heart
2. Voluntary (skeletal) is the muscle that cause body movement. They work as antagonistic pairs
  1. Antagonistic muscle pairs are composed of two muscles that have opposite effects to each other
3. Involuntary (smooth) muscle is located in the intestines, bladder and blood vessels
4. Muscles can only contract
Arthritis
1. Caused by swelling of joints
2. Prevention: reducing wear and tear
3. Treatment: rest; surgery to repair damage in severe cases

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The Skeleton and Muscles

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	Created by james liew over 8 years ago