• Diverse means of locomotion have evolved – swimming, hopping, walking, running, crawling, flying, gliding.
• All of these are based on one of two contractile systems – microtubules and microfilaments.  
• 3 main types of skeletons
     - hydrostatic: created by fluid in a closed body compartment
     - exoskeleton: a rigid external skeleton
     - endoskeleton: hard or leathery internal skeleton within the soft tissues

Human Skeleton
• axial skeleton – skull, backbone, rib cage
• appendicular skeleton – arms, shoulder girdle, legs, pelvic girdle
Joints
     1) fibrous - held together by collagenic fibers; usually immovable (synarthrotic)
     2) cartilaginous – usually have some movement (amphiarthrotic)
     3) synovial – moveable joints (diarthrotic) 
    1) plane - like the ankle & wrist bones
    2) hinge - like the knee & elbow
    3) pivot - between the atlas & axis
    4) condyloid - where a condyle fits in a depression; ie. the jaw
    5) saddle - like the thumb
    6) ball and socket - like the shoulder & hip
Injuries
 1) sprain - ligaments are stretched/torn
 2) cartilage injury
 3) dislocation - a bone is moved out of its proper position
 4) fracture – a break in a bone
Diseases
 1) arthritis - inflammation and/or degeneration of the joints
     a) osteoarthritis - "wear & tear" arthritis; gets worse as you get older
     b) rheumatoid arthritis - most severe type; causes severe inflammation of the joints
 2) osteoporosis – loss of calcium leads to porous, brittle bone; most common in older women
Cartilage
     1) hyaline – smooth, collagenic; ex. nose, larynx, ribs
     2) elastic – ex. ear, epiglottis
     3) fibrocartilage – ex. intervertebral discs, knee joints
Ligaments – connect bones to bones
Marrow
1) yellow marrow – mostly stored fat
2) red marrow – produces blood cells
Bone Functions
1) support
2) protection
3) movement
4) mineral storage
5) blood cell formation
Bones you need to be able to label:
Cranium, mandible, vertebrae, clavicle, scapula, sternum, rib, humerus, radius, ulna, carpals, metacarpals, phalanges, pelvis, femur, patella, tibia, fibula, tarsals, metatarsals

Muscles
• Bones & muscles work together for support and movement.  
• Muscles are connected to bones by tendons.
• Muscle tissue works by contracting and relaxing; one muscle contracts while opposing muscle(s) relaxes.
• Muscle tissue is made up of muscle fibers.
• Muscle fibers are made up of myofibrils.
• A myofibril is made up of a series of sarcomeres end to end.
• Thin and thick filaments in each sarcomere slide against each other to contract.
• A motor unit is a neuron and the muscle fibers it controls. 
• Acetylcholine is released to cause the muscle to contract.
• Aerobic exercise requires more oxygen and increases the efficiency and fatigue resistance of muscles.
• Anaerobic exercise builds larger, stronger muscles.