Muscle Function Terminology

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Questions and Answers

Which type of muscle is characterized as involuntary and striated, found in the walls of the heart?

Cardiac muscle (correct)

Voluntary muscle

Smooth muscle

Skeletal muscle

What is the main distinction between one joint muscles and two joint muscles?

One joint muscles are always voluntary, whereas two joint muscles are always involuntary.

One joint muscles affect only one joint, while two joint muscles affect two joints. (correct)

One joint muscles do not exert force.

One joint muscles are typically larger than two joint muscles.

What role does the brachialis muscle play when performing a bicep curl?

Antagonist during elbow flexion

Agonist during elbow flexion (correct)

Stabilizer during elbow extension

Prime mover for forearm supination

Smooth muscles are controlled by which part of the nervous system?

Autonomic nervous system Signup and view all the answers

Which classification of muscles primarily facilitates the motion of moving a joint in the opposite direction?

Antagonist Signup and view all the answers

What is the correct order of muscle attachment in relation to movement?

Origin to insertion Signup and view all the answers

What type of muscle provides the force needed to move the skeletal levers?

Skeletal muscles Signup and view all the answers

Which of the following is not a characteristic of skeletal muscle?

Involuntary control Signup and view all the answers

What is the primary role of synergist muscles during movement?

To assist, stabilize, and neutralize around a joint. Signup and view all the answers

Which of the following describes an eccentric contraction?

Muscle lengthens while generating tension against resistance. Signup and view all the answers

In the context of muscle roles, which example best illustrates a neutralizer action?

Internal rotators of the hip acting during hip flexion. Signup and view all the answers

Which contraction type occurs when holding a weight in a fixed position with no movement at the joint?

Isometric Signup and view all the answers

During knee extension, which part of the quadriceps primarily shortens to create movement?

All quadriceps muscles act concentrically. Signup and view all the answers

Which of the following defines an isokinetic contraction?

Muscle contractions occur at a constant speed. Signup and view all the answers

Which scenario exemplifies a situation where co-contraction occurs?

Biceps and triceps firing simultaneously while holding an arm extended. Signup and view all the answers

What is the key characteristic of isotonic contractions?

Muscle tension does not change while the muscle length varies. Signup and view all the answers

Study Notes

Muscle Function Terminology

Muscle Roles: Muscles can be classified based on their role in movement
- Agonist/Prime Mover: Muscle causing the desired movement
- Antagonist: Muscle opposing the movement caused by the agonist
- Synergist: Assists the agonist by either:
  - Enhancing the movement
  - Neutralizing unwanted movements
  - Stabilizing a joint during movement
- Co-contraction: Simultaneous activation of agonist and antagonist muscles
Muscle Types: Muscles can be classified by the type of movement they produce
- Isotonic: Muscle tension remains constant while the muscle length changes
  - Concentric: Muscle shortens as it contracts (origin and insertion move closer)
  - Eccentric: Muscle lengthens as it contracts (origin and insertion move farther apart)
- Isometric: Muscle contracts but there is no change in length
- Isokinetic: Muscle contracts at a constant speed. Requires specialized equipment

Muscle Classification

Skeletal Muscle: Voluntary, striated muscles responsible for moving bones
- Origin: Attachment point that moves the least, usually more proximal
- Insertion: Attachment point that moves the most, usually more distal
Cardiac Muscle: Involuntary, striated muscle found in the heart (myocardium)
- Self-contracting but its rhythm is regulated by pacemaker cells
Smooth Muscle: Involuntary, non-striated muscle found in internal organs (bowels, vessel walls)
- Controlled by the autonomic nervous system

Muscle Classifications by Joint Involvement

One-Joint Muscle: Affects a single joint only (e.g., vastus medialis)
Two-Joint Muscle: Affects two joints (e.g., rectus femoris, biceps)
Multi-Joint Muscle: Affects multiple joints (e.g., finger flexors)

Examples of Muscle Roles and Movements

Brachialis: Originates on the humerus, inserts on the ulna
- Agonist: Elbow flexion
- Antagonist: Elbow extension
Biceps Brachii: Prime mover for elbow flexion when the forearm is supinated
- Synergist: Muscles that might assist include the brachialis and brachioradialis
Rotator Cuff: Stabilizes the shoulder during movements involving the deltoid
- Fixator: Contracts to maintain the position of the humerus while other muscles move it
Abdominals vs. Back Extensors:
- Bending down and touching toes involves a combination of both muscle groups
- Abdominals flex the torso, while the back extensors extend it.

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Description

This quiz explores the terminology and classifications related to muscle functions. Learn about the roles of agonist, antagonist, synergist, and the types of muscle contractions including isotonic, isometric, and isokinetic. Test your understanding of how muscles work together to produce movement.