levers Flashcards
what is a lever?
a mechanical device in which effort force causes the rotation of bones about a fixed point (joints)
what’s a first class lever?
fulcrum lies between the effort and the load
what’s a second class lever?
load lies between the effort and fulcrum
what’s a third class lever?
effort lies between the load and fulcrum
in the human body, what represents the effort, load and fulcrum?
effort= muscles
load= bones
fulcrum= joints
what is the effort arm in a lever system?
the distance between the fulcrum and the effort in a lever system
what is the load arm in a lever system?
the distance between the fulcrum and the load in a lever system
what are the two examples of a first class lever?
extension at the neck
extension at the elbow
what’s the mechanical advantage of a lever system?
when the effort arm is longer then the load arm enabling it to overcome heavy loads
what’s the mechanical disadvantage of a lever system?
when the load arm is longer then the effort arm allowing the lever to move quicker
what’s the only example of a second class lever?
ankle during plantar flexion
