Muscle Action Flashcards
How do muscles reverse the action it produced?
-they can’t
-there are corresponding muscles/groups that can do the opposite action
What are the functional types of muscle action?
agonist (prime mover)
antagonist
synergist
fixators
Describe agonist action
contraction is mainly responsible for generating a specific movement
example of agonist
biceps brachii in elbow flexion
Describe antagonist action
-action opposes agonist
-stretches and controls extent and speed of movement
-can also be prime movers in own right
Example of antagonist
triceps brachii in elbow flexion
Describe synergist action
-assists agonist in generating movement
-provides additional pull on the insertion or stabilizes structures near the origin
example of synergist
teres minor helping initial downward movement of arm by latissimus dorsi
describe fixator action
-agonists and antagonists contract together to stabilize the proximal end of a structure while the action occurs at the distal end
example of fixator
wrist joint is fixed during flexion of fingers
What are levers?
-rigid systems moving around a fixed point, the fulcrum(a joint)
What is the applied force?
-produces the movement
-force exerted by muscle contraction
What is the resistance?
-opposes the movement
-weight of the body part that you are moving
How many classes of levers are there?
3
Describe a first-class lever
-applied force and resistance are on opposite sides of fulcrum
-can change the amount of force transmitted to the resistance and alter the direction and speed of movement
e.g. nodding your head
