Muscular System

• The agonist contracts/shortens to create the movement
• The antagonist relaxes/lengthens to co-ordinate the action
• The fixator is a muscle that stabilises one part of the body while another causes the movement.
• Isotonic contraction is a change in length during the contraction
• Concentric contraction is when a muscle shortens producing tension. Produces the force to pull two bones together, causing a joint movement.
• Eccentric contraction is when a muscle lengthens producing tension. This resists forces such as gravity, to control joint movement.
• Isometric contraction is when the muscle contracts but does not change length. The muscle creates tension as it pulls on the tendon attachment; however no movement is created.
• The three muscles at the ankle joint are the tibialis anterior, gastroscemius and soleus.
• At the wrist joint there are wrist flexors and wrist extensors.
• At the elbow joint there is the bicep branchii and the tricep branchii.
• The shoulder joint includes anterior deltoid, posterior deltoid, lattisimus dorsi, middle dorsi and the pectoral major
• The rotator cuff is made of the teres major, subsacpularis, teres minor and infraspinatous
• The hip joint consists of the adductor brevis, adductor longus, adductor magnus, gluteus medius, gluteus minimus and the gluteus maximus
• The agonist for flexion in the shoulder joint is the anterior deltoid
• The agonist for extension in the shoulder is the posterior deltoid
• The agonist for adduction in the shoulder joint is the latissimus dorsi
• The agonist for abduction in the shoulder joint is the middle deltoid
• The agonist for horizontal flexion in the shoulder joint is the pectoral major
• The agonist for horizontal extension in the shoulder joint is the posterior deltoid
• The agonist for medial rotation in the shoulder joint is the teres major and subscapularis
• The agonist for lateral rotation in the shoulder joint is the teres minor and infraspinatous
• The agonist for flexion in the hip joint is the iliopsoas
• The agonist for extension in the hip joint is the gluteus maximus
• The agonist for adduction consists of three muscles the adductor brevis, adductor longus and adductor magnus
• The agonist for abduction in the hip joint consists of two muscles the gluteus minimus and gluteus medias
• The agonist for lateral rotation in the hip joint is the gluteus maximus
• The agonist for medial rotation in the hip is the gluteus medias and minimus
• A motor neuron is a nerve cell which conducts a nerve impulse to a group of muscle fibres
• A motor unit is a motor neuron and the muscle fibre stimulated by its axon
• The motor neuron's function is to carry nerve impulses from the brain and spinal cord to the muscle fibres
• Action potential cannot cross the synaptic cleft without a neurotransmitter
• A neurotransmitter is a chemical (acetylcholine) produced and secreted by a neuron which transmits the nerve impulse across the synaptic cleft to the muscle fibre
• 1. Nerve impulse initiated in the motor neuron cell body
  2. Nerve impulse conducted down the axon of the motor neuron by a nerve action potential to the synaptic cleft
  3. Neurotransmitter called acetylcholine is secreted into synaptic cleft to conduct the nerve impulse across the gap
  4. If the electrical charge is above the threshold the muscle fibre will contract
  5. This happens in an all or none fashion
• Slow oxidative is used as an endurance athlete which is aerobically
• Slow oxidative = type 1
• Slow oxidative is designed to store oxygen in myoglobin and process oxygen in mitochondria
• Slow oxidative produce small amount of force over a long period of time
• Fast oxidative glycolytic = type 2a
• Fast oxidative glycolytic is designed to produce a large amount of force quickly. Capacity to resist fatigue. High intensity e.g 800m
• Fast glycolytic = type 2b