Types of Muscles Flashcards
What are muscles that produce a particular movement called?
Muscles that are most responsible for producing a particular movement are called prime movers, or agonists.
What are muscles that oppose or reverse a movement called?
Muscles that oppose or reverse a movement are called antagonists.
What happens to antagonist fibers when a prime mover is active?
When a prime mover is active, the fibers of the antagonist are stretched and in the relaxed state.
Can antagonists also be prime movers?
Yes, antagonists can be prime movers in their own right.
Give an example of a prime mover and its antagonist.
The biceps muscle of the arm is a prime mover of flexion at the elbow, while the triceps is the antagonist, a prime mover of extension at the elbow.
Example: Biceps (flexion) vs. Triceps (extension)
What are synergists?
Synergists aid the action of agonists either by assisting with the same movement or by reducing undesirable or unnecessary movement.
What role do synergists play in muscle contraction across multiple joints?
Synergists stabilize joints to prevent unwanted movement when a muscle crosses two or more joints.
Provide an example of synergists stabilizing a joint.
The muscles that flex the fingers cross both the wrist and finger joints, but you can make a fist without bending at the wrist because synergist muscles stabilize the wrist joint.
Example: Finger flexors and wrist stabilization
What are fixators?
Fixators, or fixation muscles, are specialized synergists that immobilize the origin of a prime mover.
What is the function of fixators?
Fixators ensure that all the tension is exerted at the insertion of a prime mover.
What types of muscles are considered fixators?
Muscles that help maintain posture and muscles of the back that stabilize or ‘fix’ the scapula during arm movements are considered fixators.
