MUSCULOSKELETAL SYSTEM AND LEVERS Flashcards
What kind of structure is the lever?
Rigid structure
How does a lever move?
Moves on a fixed point known as fulcrum (Fc)
What does the lever move?
A weight (W)
What is requried to move weight generated by muscle contraction?
Force (F)
What is first-class lever?
Fulcrum (Fc) located between muscle force (F) and weight (W)
What happens during first-class lever?
Increases range and speed of movement, but requires larger force
What is an example of first-class lever?
Skull; not many examples in the body
Which way is the force being pushed in first-class lever?
Down
What is second-class lever?
Weight (W) is located between muscle force (F) and fulcrum (Fc)
What happens during second-class lever?
Increases force, but at the expense of range and speed of movement
What is an example of second-class lever?
In the foot/calf; not many examples in the body
Which way is the force being pushed in second-class lever?
Up
What is third-class lever?
Force (F) is applied between weight (W) and fulcrum (Fc)
What happens during third-class lever?
Increase range and speed of movement, but at the expense of force
What is an example of third-class lever?
In the arm/forearm; most common in the body
Which way is the force being pushed in third-class lever?
Up
What is the action of lesser gluteal muscles?
Abduction of thigh at hip joint
What is the function of the lesser gluteal muscles?
Keep the pelvis from titling down on unsupported side (side of swinging leg) during walking
