Movement & Muscle Actions Flashcards
Musculoskeletal System (10 cards)
Explain how paired muscles work together to create movement
Muscles can only contract meaning they can pull bones together, but they cannot push them apart.
If muscles contract, pulling a bone in one direction, another set of muscles must contract to pull the bone in the opposite direction.
What are the stabiliser muscles?
Synergists and Fixators
What are synergists?
Muscles that help the prime mover.
May produce the same movement as the prime mover or steady a joint during a particular movement so that unwanted movement is prevented, and the agonist can function more efficiently.
Provide an example of a synergist muscle?
The wrist would flex every time the fist was clenched if it were not for synergist muscles, because the muscles that curl the fingers also pass across the wrist.
Synergist muscles immobilise the wrist and stop it from flexing.
What is the fixator muscle?
When a synergist immobilises a joint in this way it is called a fixator.
A fixator muscle acts as a stabiliser of one part of the body during movement of another part.
Provide an example of a fixator muscle
The many muscles that attach the scapula to the axial skeleton.
How do antagonists muscles provide movement?
Coordination of the paired muscles provides body movement, with one of the pair producing movement of bones in one direction and the other producing movement in the opposite direction.
Antagonists have opposite actions.
Provide an example of antagonist muscles
The muscles of the upper arm.
1. The front part of the bicep is fixed to the scapula, while the other end is attached to the radius.
2. The triceps is fixed to the scapula and to the humerus on one end, and to the ulna at the other end.
3. To move the forearm about the elbow joint, these two muscles must cooperate.
4. When the bicep (agonist) contracts to bend the arm, the triceps must relax.
5. The opposite occurs when the arm is straightened, and the roles are reversed.
What is an agonist?
A muscle that causes a desired action.
Provide an example of agonist muscles
While the biceps are contracting, the triceps is relaxing.
In this situation the bicep is the agonist, because it moves the forearm; the triceps is the antagonist because it has an effect that is opposite to that of the agonist
