Skeletal and muscular systems

• What are the two main components of the skeletal system?

  Axial skeleton and appendicular skeleton
• What are the common features of a synovial joint?

  • Ligament: Connects bone to bone and stabilizes joints
  • Synovial fluid: Lubricates and nourishes articular cartilage
  • Articular cartilage: Smooth tissue covering articulating bones
  • Joint capsule: Encloses and strengthens the joint
  • Bursa: Reduces friction between tendons and bones
• What is the function of synovial fluid in a joint?


  It reduces friction and nourishes articular cartilage
• What is a joint?


  A joint is an area where two or more bones articulate to create movement
• What are the three planes of movement in the anatomical position?


  • Sagittal plane: Divides the body into left and right
  • Frontal plane: Divides the body into anterior and posterior
  • Transverse plane: Divides the body into upper and lower
• What movement occurs in the sagittal plane?


  Flexion and extension
• What is an example of flexion in the sagittal plane?


  Bending the arm at the elbow
• What is the movement pattern for the frontal plane?


  Abduction and adduction
• What type of joint is the shoulder joint?


  Ball and socket joint
• What are the movement patterns possible in a ball and socket joint?


  • Sagittal plane: Flexion and extension
  • Frontal plane: Abduction and adduction
  • Transverse plane: Horizontal flexion, horizontal extension, medial and lateral rotation
• What is the agonist muscle for flexion at the shoulder joint?


  Anterior deltoid
• What is the role of the posterior deltoid during shoulder adduction?


  It acts as an agonist muscle
• What type of joint is the elbow joint?

  Hinge joint
• What are the articulating bones of the elbow joint?


  Humerus, radius, and ulna
• What is the agonist muscle for extension at the elbow joint?


  Triceps brachii
• What type of joint is the knee joint?


  Hinge joint
• What are the articulating bones of the knee joint?

  Femur and tibia
• What is the role of the biceps femoris during knee flexion?


  It concentrically contracts to flex the knee joint
• How does the knee joint contribute to a penalty shot in football?


  • Flexion: Biceps femoris contracts in preparation phase
  • Extension: Rectus femoris contracts in execution phase
  • Creates power and large force to apply to the football
• What is the term for the movement that involves pointing the toes downwards?

  Plantar flexion
• How do contemporary dancers use plantar flexion?


  They use it to shape bodily movements and create a fully extended position in a split leg or when rising to the toes.
• What are the functional roles of muscles during movement?

  • Agonist: muscle responsible for creating movement
  • Antagonist: muscle that opposes the agonist
  • Fixator: muscle that stabilizes one part of the body while another part moves
• What is the process called when muscles shorten to produce movement?

  Muscle contraction
• What happens to muscle fibers during contraction?


  Groups of muscle fibers shorten in length, causing the muscle to shorten and produce movement.
• What is the relationship between the number of muscle fibers contracting and muscle action?


  The more muscle fibers that contract together, the more powerful the muscle action produced.
• What are the three main roles of muscles in movement?

  1. Agonist
  2. Antagonist
  3. Fixator
• What are common antagonistic muscle pairings for elbow flexion and extension?

  • Flexion of elbow: Agonist - Biceps Brachii, Antagonist - Triceps Brachii
  • Extension of elbow: Agonist - Triceps Brachii, Antagonist - Biceps Brachii
• What type of contraction occurs when a muscle shortens to produce tension?

  Concentric contraction
• What is an example of an eccentric contraction?


  During the downward phase of a biceps curl, the biceps brachii eccentrically contracts to lower the weight.
• What is the term for a muscle that contracts but does not change length?

  Isometric contraction
• What is the role of acetylcholine in muscle contraction?


  Acetylcholine helps the nerve impulse cross the synaptic cleft to initiate muscle contraction.
• What is the process that occurs at the neuromuscular junction?


  1. Nerve impulse initiated in the motor neurone cell body
  2. Conducted down the axon to the synaptic cleft
  3. Acetylcholine secreted into the synaptic cleft
  4. If electrical charge is above threshold, muscle fiber contracts
  5. Follows the all-or-none law
• What is the small gap between the motor end plates and muscle fibers called?

  Synaptic cleft
• How does the strength of muscle contraction relate to motor units?


  The greater the number of motor units recruited, the greater the strength of contraction.
• What are the characteristics of slow oxidative muscle fibers?


  • Small fiber size
  • High capillary density
  • High myoglobin density
  • High mitochondria density
  • High fatigue resistance
  • Used for endurance activities
• What are the characteristics of fast glycolytic muscle fibers?


  • Large fiber size
  • Low capillary density
  • Low myoglobin density
  • Low fatigue resistance
  • Recruited for maximal efforts quickly
• What is delayed onset muscle soreness (DOMS)?


  It is pain and stiffness felt in the muscle which peaks 24-72 hours after exercise.
• What is the recommended recovery time for fast glycolytic fibers after maximal weight training?


  • 4-10 days to recover
  • 48 hours before using the same muscle group again
• What is the significance of the all-or-none law in muscle contraction?


  • If the stimulus is above threshold, all muscle fibers will contract completely.
  • If the stimulus is below threshold, no contraction occurs.