biomechanics of movement Flashcards
(22 cards)
what are the 4 basic components to a lever system?
- lever arm (rigid bar)
- fulcrum (point of rotation)
- resistance
- applied force
what serves as the lever arm in vertebrates?
skeletal components (bones)
what serves as the fulcrum in vertebrates?
joint, or at the ground surface
what serves as the resistance in vertebrates?
- gravity, inertia
- placement of body parts against a relatively immovable object
what serves as the applied force in vertebrates?
muscle contraction
where is the fulcrum positioned in a first class lever system/
between the force and the resistance
-e.g. cubital joint extension by triceps brachii
how is a second class lever system positioned?
the resistance is positioned between the fulcrum and the force
-e.g. the tarsal joint extension by gastrocnemius
what class of lever system is it if the limb is free to swing?
first class
what class of lever system is it if the limb is planted on the ground?
second class
how is a third class lever system positioned?
the force is between the resistance and the fulcrum
-e.g. cubital joint flexion by biceps brachii
what class of lever describes the pull of the gluteal mm on the greater trochanter when the femur is free to swing caudally?
first class
extension of the carpal joint(s) by the extensor carpi radialis m. is an example of which class of lever?
third class
the appied force necessary to cause (or prevent) movement depends on the ____ distance of the forces from the fulcrum and is subject to change throughout the range motion.
perpendicular
T/F: All movement is produced by lever systems.
false
there will be increased tension but no movement when resistance force ____ the applied force.
resistance force EQUALS the applied force.
a muscle that produces a certain referenced effect or movement
agonist
a muscle capable of actively opposing a movement
antagonist
a muscle that may neither facilitate nor directly oppose the movement but may modify the action of the agonist, perhaps eliminating an unwanted side effect?
synergist
a muscle that is employed to stabilize a joint rather than promote its movement
fixator
contraction of what muscle would prevent extension of the humeral joint during flexion of the cubital joint by the biceps brachii m.?
deltoideus m.
in what phase of the stride is the limb in contract with the ground?
stance phase
in what portion of the stride is the limb not in contact with the ground?
swing phase
