L4;C6 Flashcards
What are muscles comprised of?
- muscle fibres
Wha do muscle fibres consist of?
Myofibrils
What are myofibrils?
These are the contractile elements and consist of myosin and actin that are arranged in sarcomeres
What are the three types of connective tissue?
Epimysium- surrounds entire muscle
Perimysium- surrounds fascicles (msuclar fibre)
Endomysium- surrounds entire muscle fibre
Muscles develop ____ and _____ when they contract
Force, stiffness
Stiffness is resistance to ______ ______
Changed length
Stiffness and force are ______ and ______ functions to controlling body segmental position and motion.
Direct, indirect
Bones ______ and ______
While joints _______ and ______
Bend, deform
Compress, shear
It takes longer for what kind of fibre to reach peaks tension? Fastest?
Slow twitch, fast twitch
What are motor units?
These are single motor neurons and all the fibres it innervates
When would you have fewer muscle fibres?
For more precise movements, such as extra ocular muscles
What are the five factors affecting muscle force production in the Muscle Tendon Complex?
Motor unit recruitment Motor unit discharge rate Motor unit discharge pattern Mechanical structural factors Temporal factors
Describe the motor unit recruitment factor
This is the size principle (Henneman). MUs are usually activated in orderly fashion (smallest to largest)
Describe the motor unit discharge rate factor
As MU stimulation frequency increases, muscle force increases. More activation means more force, we can vary with discharge.
Describe the five mechanical structural factors
Muscle length, muscle shortening/length velocity, muscle fibre arrangement physiological cross sectional area Properties of fibres (FT vs ST)
Describe the temporal factors
This is a time factor:
- force enhancement after stretching (SS cycle)
- stretching and force prior to movement produces most force
What is active insufficiency?
This is when force production is limited when multi articular muscles are shortened. you are are unable to produce full RoM at all joints crossed simultaneously.
What is passive insufficiency?
RoM at all joints crossed is simultaneously limited when multi articular muscles are fully stretched
What are two rate limiting factors with regards to force velocity relations?
- Cross bridges form, its harder for them to break
- rate of length of the actual muscle will determine force
For concentric, as velocity _______ force _______
For eccentric, as velocity __________ force _________
Increases, decreases
Increases, increases to a plateau
What is power defined as? When is peak power usually hit with regards to force? Does high force mean lots of power?
Power is defined as High rates of force
Peak power is usually hit around 30% force
High force does not equal high rates of power
Name the two fibre arrangements and their descriptions?
Parallel- every time they shorten the entire muscle shortens (biceps)
Pennate- more pennate muscles together is a stronger muscle, we can pack more of these in a space.
Name the four behavioural properties of muscles
Extensibility-muscles have the ability to be stretched
Elasticity- muscles recoil and return to normal length after being stretched
Irritability- muscles respond to mechanical and electrical stimuli
Contractibility- muscles have the ability to develop tension
What is the net muscle torque?
the force produced by muscles to move the object
What does muscle visoelasticity allow?
This enables it to progressively lengthen over time when stretched.
Pennate fibres produce more ______ parallel fibres ________ muscle shortening
Force, facilitate
