Muscle Actions quiz #1 Flashcards
Muscle Actions quiz #1
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What is the role of the agonist (prime mover) in muscle actions?
The agonist, or prime mover, is the main muscle responsible for producing a specific movement. During elbow flexion, which muscle acts as the agonist?
The biceps brachii acts as the agonist during elbow flexion. What is the function of the antagonist muscle during movement?
The antagonist muscle opposes the action of the agonist, relaxing to allow the movement to occur. Which muscle serves as the antagonist during elbow flexion?
The triceps brachii serves as the antagonist during elbow flexion. How do agonist and antagonist muscles interact during movement?
Agonist and antagonist muscles work in opposition; as the agonist contracts, the antagonist relaxes to allow movement. What is a synergist muscle?
A synergist muscle aids the prime mover by working together to enhance or assist the movement. Give an example of a synergist during elbow flexion.
The brachialis acts as a synergist during elbow flexion, assisting the biceps brachii. What is the role of a fixator muscle?
A fixator muscle stabilizes the origin of the prime mover to ensure effective movement. Which muscle group acts as a fixator during arm movements?
The rotator cuff muscles act as fixators by stabilizing the humerus during arm movements. Why is it important for the fixator to stabilize the origin of the prime mover?
Stabilizing the origin allows the prime mover to act efficiently and prevents unwanted movement at the origin. Can a muscle act as both a prime mover and a synergist? Explain.
Yes, a muscle can act as both a prime mover and a synergist depending on the movement and the muscles involved. What happens to the antagonist muscle when the agonist contracts?
The antagonist muscle relaxes to allow the movement initiated by the agonist. How do synergists contribute to muscle movement?
Synergists contribute by adding force, stabilizing joints, or preventing unwanted movements during the action. What is the main difference between a synergist and a fixator?
A synergist assists the prime mover in performing the movement, while a fixator stabilizes the origin of the prime mover. Describe the role of the triceps brachii during elbow extension.
During elbow extension, the triceps brachii acts as the agonist (prime mover). What is meant by the term 'prime mover' in muscle actions?
The 'prime mover' refers to the main muscle responsible for generating a specific movement. How do fixators help maintain posture during movement?
Fixators stabilize certain body parts, allowing other muscles to move efficiently and helping maintain posture. Why is it important for antagonists not to relax completely during movement?
Partial contraction of antagonists helps control and stabilize the movement, preventing injury and ensuring smooth motion. What is the origin and insertion of a muscle, and how do they relate to movement?
The origin is the fixed attachment point, and the insertion is where the muscle attaches to the moving bone; contraction pulls the insertion toward the origin. How does the rotator cuff function as a fixator during lifting movements?
The rotator cuff stabilizes the humerus, allowing the arm muscles to lift objects effectively. What would happen if fixator muscles did not function properly during movement?
If fixators did not function, the origin of the prime mover would move, leading to inefficient or uncontrolled movement. Explain the relationship between the biceps brachii and triceps brachii during elbow movements.
During elbow flexion, the biceps brachii is the agonist and the triceps brachii is the antagonist; during extension, their roles reverse. Can a muscle act as an agonist in one movement and an antagonist in another? Give an example.
Yes; for example, the biceps brachii is the agonist during elbow flexion and the antagonist during elbow extension. What is the benefit of having multiple synergists during a movement?
Multiple synergists increase force, improve control, and reduce the risk of injury by sharing the workload. How do muscles work together to produce smooth and coordinated movements?
Muscles work together as agonists, antagonists, synergists, and fixators to balance forces and stabilize joints for smooth movement. What is the main function of the brachialis muscle during elbow flexion?
The brachialis acts as a synergist, assisting the biceps brachii in flexing the elbow. Why is it sometimes difficult to distinguish between a prime mover and a synergist?
Some muscles contribute equally to a movement, making it hard to label one as the prime mover and the other as a synergist. How does understanding muscle roles help in learning body mechanics?
Understanding muscle roles clarifies how movements are produced and controlled, aiding in the study of body mechanics. What is the effect of muscle contraction on the insertion and origin?
Muscle contraction pulls the insertion toward the origin, causing movement at the joint. How do antagonists contribute to joint stability?
Antagonists provide resistance and control, helping stabilize joints during movement. What is the significance of the rotator cuff in shoulder stability?
The rotator cuff stabilizes the shoulder joint, preventing dislocation and allowing effective arm movement. Describe a scenario where a fixator muscle is essential for movement.
When lifting an object overhead, fixator muscles stabilize the scapula, allowing the arm muscles to lift efficiently. How do synergists prevent unwanted movements during an action?
Synergists stabilize joints and neutralize extra movements, ensuring the desired action occurs smoothly. What is the role of the triceps brachii during elbow extension?
The triceps brachii acts as the agonist (prime mover) during elbow extension. How does the biceps brachii function during elbow extension?
During elbow extension, the biceps brachii acts as the antagonist, relaxing to allow the movement. Why do muscles need to work in groups rather than individually?
Muscles work in groups to produce coordinated, controlled, and efficient movements. What is the importance of muscle relaxation in movement?
Muscle relaxation allows opposing muscles to contract and produce movement without resistance. How do fixators differ from other synergists?
Fixators specifically stabilize the origin of the prime mover, while other synergists assist with the movement itself. What is the function of the rotator cuff during arm abduction?
The rotator cuff stabilizes the humerus, allowing the deltoid to abduct the arm effectively. How does the concept of agonist and antagonist apply to knee flexion and extension?
During knee flexion, the hamstrings are agonists and the quadriceps are antagonists; during extension, their roles reverse.
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