Muscular system Flashcards
What is an agonist/prime mover?
The muscle that is shortening with force to initiate or cause the movement
What is the antagonist?
Muscle lengthening in opposition to the agonist
What is the fixator?
Muscle static, stabilises joint to make movement more efficient
What is a contraction?
When a muscle changes in length with a force
What are the 3 types of contraction?
Concentric
Eccentric
Isometric
What is a concentric contraction?
When the muscle shortens while exerting a force
What is an eccentric contraction?
When the muscle lengthens while exerting a force
What is an isometric contraction?
No change in muscle length but it is exerting a force
What are the pairs of muscles that work together to make movement called?
Antagonistic pairs (normally, the agonist concentrically shortens and the antagonist lengthens in opposition)
What are the 4 stages of answering a movement analysis question?
- Muscle length (shortening/static/lengthening)
- Muscle function (agonist)
- Type of muscle contraction
- Plane of movement
What 3 muscles are in your hamstring?
What 3 muscles cause flexion at the knee?
Biceps femoris
Semitendinosus
Semimembrinosus
What 4 muscles are in your quadricep?
What 4 muscles cause extension at the knee?
Rectus femoris
Vastus medialis
Vastus lateralis
Vastus intermedialis
What causes flexion at the hip?
Illiopsoas
What causes extension at the hip?
Gluteus maximus
What causes abduction at the hip?
Gluteus medius
What causes adduction at the hip?
Adductor longus
Adductor brevis
Adductor magnus
What causes medial rotation at the hip?
Gluteus medius
Gluteus minimus
What causes lateral rotation at the hip?
Gluteus maximus
What causes flexion of the spine?
Rectus abdominus
What causes extension of the spine?
Erector spinae group
Sacrospinalis
What causes lateral flexion of the spine?
External/internal obliques
What causes plantar flexion?
Gastrocnemius and soleus
What causes dorsiflexion?
Tibialis anterior
What causes flexion at the wrist?
Wrist flexors
What causes extension at the wrist?
Wrist extensors
What causes flexion at the elbow?
Biceps brachii
What causes extension at the elbow?
Triceps brachii
What causes flexion at the shoulder?
Anterior deltoid
What causes extension at the shoulder?
Posterior deltoid
What causes abduction at the shoulder?
Medial deltoid
What causes adduction at the shoulder?
Latissimus dorsi
What causes horizontal flexion at the shoulder?
Pectoralis major
What causes horizontal extension at the shoulder?
Trapezius
What causes medial rotation at the shoulder?
Teres major
Subscapularis
Anterior deltoid
What causes lateral rotation at the shoulder?
Teres minor
Infraspinatus
Posterior deltoid
What causes pronation at the radioulnar joint?
Pronator teres
What cause supination at the radioulnar joint?
Supinator
What do you include in an eccentric contraction question?
Eccentric Antagonist Lengthening Acting as a break Control movement Termed negative work as lengthening but agonist
What is your body’s core?
The area around your trunk and pelvis where your centre of mass is located.
What is the role of the core?
Act as stabilisers/fixators for the trunk/pelvis/lower vertebrae to support the forces from your arms/legs during physical activity
What are the 2 main core stability muscles?
Transverse abdominis
Multifidus
What are the benefits of a strong core?
More stable centre of mass
Reduced risk of lower back pain
Improved posture/spine alignment
More stable platform, more efficient movement of arms/legs
How do you train the core muscles?
Swiss ball training and pilates are two common methods of increasing the muscle tone/strength of the core stability muscles.
Eg the plank
What are the rotator cuff muscles roles?
They work together to provide the shoulder joint with dynamic stability, helping control the joint during rotation.
What are the 4 rotator cuff muscles? (SITS)
Supraspinatus
Infraspinatus
Teres minor
Subscapularis
What sports are rotator cuff muscles important in?
Throwing sports
They stabilise the shoulder joint when releasing the ball, despite the massive forces involved in slowing the arm down after release.
What are the common injuries for rotator cuff muscles?
Tears of tendons/muscles and inflammation of structures in the joint are common problems as they are put under a lot of stress in sports that involve lots of shoulder rotation
When do rotator cuff muscles need to be strengthened?
When athletes need to repeatedly produce vigorous overhead movements or are involved in contact sports.
What makes up the central nervous system?
Brain and spinal chord
How does the motor division of the brain transmit information from the CNS to the muscles?
Via efferent motor neurons which are part of the somatic nervous system
What are motor neurons made of?
Dendrites, cell body, axon, myelin sheath, nodes of ranvier and axon terminals/motor end plates.
What are neuromuscular junctions?
Where motor end plates meet muscle fibres
What are motor units?
Motor neurone and the muscle fibres it innervates
How many muscle fibres can a motor neuron innervate?
Between 15 and 2000 muscle fibres
What is the term given to an inactive neuron?
Polarised
Negative charge inside the cell
Positive charge outside the cell
What is a polarised neuron waiting for?
It is awaiting the next action potential to be generated. The neuron is ready to fire.
What does a neural impulse cause?
Depolarisation
Positive charge inside cell
Negative charge outside cell
What is the threshold level that needs to be reached?
-55mV
What happens when the threshold level is reached?
Neuron fires a full action potential
Impulse passes down neuron over the myelin sheath.
What happens at the motor end plates?
It turns the action potential into a chemical neurotransmitter which passes the message to next motor neuron/muscle fibre across the synapse.
What does the myelin sheath do?
Insulates the axon and speeds up the transmissions of an action potential.
Where do depolarisation and action potentials occur?
Depolarisation and action potentials can only occur at the nodes of Ranvier.
Action potential travels along axon of motor neuron over the myelin sheath jumping from one node of Ranvier to another.
What is the method of propagation termed as?
Saltatory conduction
How much quicker is action potential in myelinated axons compared to unmyelinated axons.
5-150 times quicker
What is different about fast twitch fibres?
The neurons have a larger diameter which means they present less resistance to current flow which conducts the nerve impulses faster.
How is the nerve impulse transmitted along a motor neuron?
AP=Action potential
Named propagation, termed saltatory conduction
CNS transmits AP to the muscles via efferent motor neurons
Neural impulse causes depolarisation positive in negative out of cell
Dendrites receive impulse, conduct through cell body, AP transmitted along axon, over myelin sheath, jumping from one node of Ranvier to another.
How do neurons communicate with each other?
By releasing neurotransmitters across synapses.
What is a synapse?
Junction between 2 neurons.
The site where a nerve impulse is transmitted between 2 neurons.
How is an impulse transmitted between neurons?
An impulse travels to a pre-synaptic axon terminal causing synaptic vesicles on the terminal to release neurotransmitters into the synaptic cleft. Neurotransmitters bind to post synaptic receptors on an adjacent neuron (dendrites)
What occurs at a neuromuscular junction?
AP=Action Potential
An impulse is transmitted between a motor neuron and a muscle fibre. Motor end plate stimulates synaptic vesicles which release neurotransmitters which travel across the synaptic cleft and bind to receptors on a muscle fiber causing depolarisation and possibly an AP which spreads across the sarcolemma into the T tubules causing the muscle fiber to contract.
What are the 2 neurotransmitters?
Acetylcholine
Norepinephrine
What is the all or none law?
If the stimulus causes the depolarisation threshold to be reached it fires off the action potential.
All muscle fibres innervated by that motor unit contract maximally with equal force.
If threshold not reached none of muscle fibres innervated by motor unit contract
How do you increase the force of a contraction?
Recruit more motor units (more muscle fibres)
More fast twitch muscle fibres
Increase the frequency of stimulation (wave summation)
What is the difference between slow and fast twitch fibres?
Slow have motor units that only have small numbers of muscle fibres (100 fibres per unit)
Fast have motor units that have large numbers of muscle fibres (10,000 per unit)
What is the structure of Slow Oxidative Type 1 - slow twitch muscle fibres?
Red and small Lots of mitochondria and capillaries High myoglobin levels Low glycogen stores Thin myelin sheath
What is the structure of Fast Oxidative Glycolytic Type 2a muscle fibres?
Red/white and intermediately sized Moderately high number of mitochondria Moderate number of capillaries and myoglobin levels High glycogen stores Thick myelin sheath
What is the structure of Fast Glycolytic Type 2b muscle fibres?
White and large Few mitochondria/capillaries Low myoglobin levels High glycogen stores Thickest myelin sheath
What is the function of Slow Oxidative Type 1 - slow twitch muscle fibres?
Slow contractile speed
Low contractile strength
High fatigue resistance and aerobic capacity
Low anaerobic capacity
What is the function of Fast Oxidative Glycolytic Type 2a muscle fibres?
Fast contractile speed Moderate contractile strength Moderate fatigue resistance Moderate aerobic capacity High anaerobic capacity
What is the function of Fast Glycolytic Type 2b muscle fibres?
Fast contractile speed High contractile strength Low fatigue resistance Low aerobic capacity High anaerobic capacity
In what order are fibre types recruited?
ST type 1 fibres are always recruited first then as the intensity/force required increases, FT type 2a fibres are recruited. At maximum work FT type 2b fibres are also recruited.
What is muscle fibre recruitment dependent on?
The force required
What is the principle of orderly recruitment?
The motor units are activated in a fixed order, based on their ranking in the muscle.
What is the size principle?
Order of recruitment is directly related to their motor neuron size.
Why are slow twitch fibres recruited first?
They have smaller motor neurons which have a lower activation threshold.
They stimulate fewer muscle fibres, slow speed, low force, high fatigue resistance.
Why are fast twitch fibres recruited second?
They have larger motor neurons which have a higher activation threshold. They stimulate more muscle fibres, produce a larger speed/force, but have a lower fatigue resistance.
What is the work:relief ratio of slow twitch fibres?
1:1 OR 1:0.5
What is the work:relief ratio of fast twitch fibres?
1:3+
Why can slow twitch fibres recover quickly?
They share the workload by contracting intermittently with a lower force of contraction without fatiguing by-products. They are ready for contraction again in about 90 seconds.
Can aerobic or anaerobic training be repeated regularly?
Aerobic as there is less muscle damage
When are fast twitch fibres recruited?
Last 2-20 seconds near exhaustion with a maximum force/speed of contraction with lactic acid as a by product.
What stores do fast twitch fibres use?
Immediate stores of ATP and PC which takes 2/3 minutes for full recovery during exercise.
What is DOMS?
Delayed onset muscle soreness.
Occurs 24-48 hours after exercise (due to microscopic muscle tears)
How long does DOMS take to recover?
Much longer than with aerobic training, 4-7 days)
