Muscles Flashcards
Contractibility
Ability of a muscle to shorten with force
Excitability
Capacity of muscles to respond to a stimulus
Extensibility
Muscles can be stretched to its normal resting length and beyond to limit degree
Elasticity
Ability of muscles to recoil to its original resting length after being stretched
What are the 3 main types of muscle ?
Skeletal, smooth and cardiac muscle
What is the function of a tendon ?
Connects bone to muscle
Helps prevent muscle injury by absorbing some of the impact
What is the function of the fascia ?
Provides support for the surrounding tissue and helps reduce friction
What is the function of a muscle ?
Responsible for movement - contraction and relaxation
What is the function of the myotendinous junction
The interface between muscle and tendon where the force is transmitted between two tissue
What is the function of the osteotendinous junction ?
Site of connection between the bone and is also the tendon insertion site
-> provides gradual transition from tendiunous to bone
What is the function of the tendon sheath ?
Protects tendons and allow target to move smoothly and freely
Also helps anchor the tendon to the muscle
What are the 4 ways muscle contraction can be stopped - explain in a sentence?
Energy systems fatigue
- no more ATP left in muscle cells so it can’t keep contracting
Nervous system fatigue
- nervous system is unable to create impulses sufficiently enough to maintain the stimulus and cause calcium to be released
Voluntary system control
- the nerve that tells the muscle to contract stops sending the signal because the Brain tells it to, no more calcium ions can enter = contraction stops
Involuntary nervous system
Involuntary nervous system control
sensory neurone (nerves that detect stimuli such as pain) provides feedback to the brain indicating that the muscle is injured while you are trying to lift a heavy weight = the impulse telling the muscle to contact is stopped
What are muscle spindles and their role?
act as stretch receptors controlling the length of the muscle
They sense how far and how fast the muscle is being stretched
Contraction = reflex hammer
What are Golgi tendons organs and their role ?
- Nerve fibres that weave between the collagen fibres of the tendon (proprioreceptors)
- Sensitive to change in muscle tension
- Muscle contracts the nerve, fibres are compressed triggering a stimulus
- Monitors extent of a muscle contraction and force exerted
- Inhibition of muscle
Muscle tone
Constant tension by the muscles for long periods of time / acting against gravity
Isotonic contraction
Change in length but tension is constant (dynamic)
-> CONCENTRIC AND ECCENTRIC
Concentric contraction
The muscle shortens
The internal force generated is greater than the external force applied
Eccentric contraction
The muscle lengthens, whilst maintaining tension
External force applied is greater than the internal force generated
Isometric contraction
No change in length but tension increases
External force = internal force
Isokinetic contraction
Occurs when the velocity of a muscle contraction remains constant while the length of the muscle changes
The force exerted in an isokinetic contraction is not fixed and varies depending on what 3 factors
Position
ROM of the joint
Effort applied
What factors affect the strength of muscle contraction
Recruitment - past experience, muscle fibres, frequency of neural stimulation of motor unit
Type of muscle fibre - fast and slow twitch
Length and tension relationship - best in mid range , maximum overlap
Age - older = slower
Height - taller = further impulses have to travel
When muscle is in the outer range what does this mean for muscle length
Muscle is at its longest
( from full stretched to mid point of the full range)
When muscle is in the inner range what does this mean for muscle length
Muscle is at its shortest
(From the midpoint to full contraction)
What is force
An influence that can change the velocity of a body
Lever
A simple machine made of a rigid beam and fulcrum
-> most joints in the body act as a lever
Fulcrum
The point around which a lever pivots
Moment
The turning effect of a force
The further away the lever is the easier it is to move ( think of a door the Handle is further away from the hinge)
Moment equation
Moment = force x distance
Varus
Bowing of the knees - point out
Valgus
Knock knees - point in
Centre of gravity
Moments acting on a body are in equilibrium
Muscle origin
Refers to one end of a muscle generally at the location where it attaches to a bone
Muscle insertion
The end of the muscle furthest away from the torso
(A muscles distal attachment)
Kinematics
Deals with just the movement of the body
Moment example of holding a weight in your hand
there are two moments
-> weight of the forearm
-> the weight of the weight in the hand
There are two forces trying to pull down these two moments.
The effort of the bicep is creating a moment in the opposite direction (anti-clockwise).
To be in equilibrium you need to have a moment pulling anticlockwise equal to the moment pulling clockwise. If moments aren’t equal then flexion can occur.
Ground reaction force
When we apply force into the ground (weight and when pushing ie walking) the ground pushes back in an equal and opposite reaction
Viscosity
Measure of resistance to flow
When muscles are working stress builds up, as load is taken off there is little lag / lingering whilst strain remains for a while
If there is a higher temperature what does this mean for viscosity
There is a lower velocity for higher temperature
-> if you warm up (ie before exercise) you can manipulate the muscles better and can overload more as you become more flexible
Creep
Progressive deformation of structure overtime when it is under constant load
-> the stress is the same throughout, with gradual deformation overtime
-> if in a constant position over time = valgus
Stress relaxation
Gradual decrease in stress without any change in the strain
Why is stress relation important
Don’t want to over stretch or overload
Tensile
Pulling on something
Hysteresis
Load increases as elongation increases
What happens if the loading occurs in a stressful way during hysteresis
It wont return to the same point of the beginning each time, some energy is lost as heat as the muscles are stretched
-> increase in heat from hysteresis = increase in velocity
Stress
Tension or exertion on a body part
Strain
Stretched or torn muscle (elongation)
