BIO10004 WK 4

• Joints are where the appendicular skeleton moves
• Articulations


  Another term for joints
• Joint strength/stability reduces with range of motion
• Joint categories by range of motion

  • Synarthrosis (no movement)
  • Amphiarthrosis (little movement)
  • Diarthrosis (free movement)
• Joint categories by structure

  • Bony
  • Cartilaginous
  • Fibrous
• Synovial joints


  Freely moveable joints with synovial fluid
• Structures of a synovial joint

  • Joint capsule (or articular capsule)
  • Synovial fluid
  • Fat pads
  • Ligaments
  • Tendons
  • Bursa(e)
• Synovial fluid


  Lubricates, provides nutrients, absorbs shocks
• Movement types


  • Flexion
  • Extension
  • Abduction
  • Adduction
  • Circumduction
  • Rotation
• Flexion


  Movement in anterior plane that decreases angle
• Extension


  Movement in anterior plane that increases angle
• Abduction


  Movement away from midline
• Adduction


  Movement toward midline
• Circumduction


  Circular motion
• Rotation types


  • Lateral (external) rotation
  • Medial (internal) rotation
  • Supination
  • Pronation
• Elbow joint


  • Complex hinge joint
  • Flexion, extension
  • Some rotation
• Knee joint


  • Hinge joint
  • Flexion, extension
  • Small amount of rotation
• Shoulder joint


  • Ball and socket joint
  • Flexion, extension
  • Adduction, abduction
  • Circumduction, rotation
• Hip joint


  • Ball and socket joint
  • Flexion, extension
  • Adduction, abduction
  • Circumduction, rotation
• Joint degeneration conditions


  • Rheumatism
  • Arthritis
  • Osteoarthritis
  • Rheumatoid arthritis
  • Gouty arthritis
• Regular exercise and movement assist with joint degeneration symptoms
• Types of muscle tissue

  • Skeletal
  • Cardiac
  • Smooth
• Skeletal muscle


  • Required to move, circulate blood, push solids and fluids in digestive tract and other organs
• Functions of skeletal muscle

  • Produce skeletal movement
  • Maintain posture and position
  • Support soft tissues
  • Guard body entrances and exits
  • Maintain body temperature
  • Store nutrients
• Skeletal muscle structure


  Muscle tissue, Connective tissue, Blood vessels, Nerves
• Skeletal muscle fibres


  Each muscle fibre has ~100-1000s of myofibrils, 1-2 µm in diameter, same length as muscle cell
• Myofibrils


  Protein bundles or myofilaments (thin actin, thick myosin)
• Sarcomere


  Interactions between sarcomeres create contractions, I band, A band, H band (M line)
• Muscle action


  1. Muscle shortening (contraction is the active process)

  2. Muscles lengthening (passive by being pulled externally)
• Nervous/muscular


  1. Axon contains neurotransmitter (ACh)

  2. Action potential travels along axon

  3. Triggers release when reaches terminal

  4. ACh diffuses across synaptic cleft

  5. Na+ inrush triggers muscle action potential
• Cardiac muscle tissue


  • Found only in the heart, excitable tissue, short small cells, striated appearance, conductive ends (intercalated disks), aerobic metabolism
• Cardiac muscle action


  Intercalated disks make electric continuity, cells are spontaneously active, rate modulated by action of nervous system
• Smooth muscle


  • Different to skeletal & cardiac muscle, regulatory role, no striations (sarcomeres), contractions spontaneous, very little nervous innervation, mainly hormonal control
• Comparison of muscle types

  • Skeletal
  • Cardiac
  • Smooth
• Muscles


  • Fascicles (bundles of muscle fibres) + connective tissue + nerves + blood vessels
• Fascicle arrangements


  • Parallel
  • Convergent
  • Pennate
  • Circular
• Parallel muscles


  Muscle fibres parallel to long axis of muscle, large proportion of muscles are this type, most have tendons at each end, contraction shortens and fattens the muscle
• Convergent muscles


  Fan shaped, narrow attaching to tendon at one end, broad attachment at other end
• Pennate muscles


  Form a common angle with tendon, direction of pull of fibres is not parallel to muscle body, generate less movement but more force
• Circular muscles


  Arranged circumferentially, also known as sphincter muscles, contraction closes the opening