MNSR 6 - Skeletal Lever Systems Flashcards
Explain what happens to muscle with age.
As a person ages, there’s a gradual decrease in the number of muscle fibers, muscle converts to intramuscular fat, and muscle and bone lose their elasticity which hinders joint movement.
What is maximum tension dependent on?
Maximum tension is dependent on 2 factors:
- cross-sectional area of muscle at its widest point
- Length of the muscle (max force is generated when the muscle is stimulated from its relaxed state)
What are the two types of muscle?
There are two types of muscle:
- Fusiform muscle: fibers run parallel to the length of the muscle.
- Pennate muscle: fibers insert into a central tendon, are at an angle to the force-generating axis & generate more force than the fusiform muscles BUT smaller range of motion. There are three types:
- unipennate: forearm
- bipennate: thigh
- multipennate: shoulder joint
Differentiate between Agonist & Antagonist Muscles.
- Agonist/Primer mover/Normal: carry out the desired movement
- Antagonist muscles: assist agonist in controlled relaxation
What can a lever do?
A lever can be used to magnify a force or change its direction.
Define Mechanical Advantage.
MA = Fi/Fa
Fa < Fi = efficient –> mechanical advantage
Fa > Fi = inefficient –> mechanical disadvantage
Discuss Class I Levers.
Fi fulcrum Fa
Fa < Fi OR Fa > Fi OR MA = 1 (EFFICIENT OR INEFFICIENT)
Head lift
Discuss Class II Levers.
Fa Fi Fulcrum
Fa < Fi OR MA > 1 (EFFICIENT)
Calf Extension
Discuss Class III Levers
Fi Fa Fulcrum
Fa > Fi OR MA < 1 (INEFFICIENT)
Bicep Curl
Define Torque.
Torque is a force which causes rotational motion about a fixed point. Toure = Force x Perpendicular Distance
Under what 2 conditions does equilibrium occur?
- Net force = zero
2. Net torque = zero
State the formula for Equilibrium and Torque.
Sum of Clockwise torque = Sum of Anti-clockwise torque
