Questions and Answers
__________ are muscles that serve as the primary promoters of a movement.
Which class of muscle has the major responsibility for a specific movement?
When the term biceps, triceps, or quadriceps forms part of a muscle's name, what does it tell you about the muscle?
A muscle group that works with and assists the action of a prime mover is a(n) ________.
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Which generalization concerning movement by skeletal muscles is not true?
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Which of the following is not used as a criterion for naming muscles?
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Choose the false statement.
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Which of the following muscles is named for its origin and insertion?
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What are the muscles that are found at openings of the body collectively called?
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Which of these is not a way of classifying muscles?
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Muscles are only able to pull, they never push.
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Muscles that help to maintain posture are often called synergists.
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Which of the following is correctly matched?
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Most skeletal muscles of the body act as:
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Which of the following movements demonstrates a first-class lever?
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Which type of lever is demonstrated by using scissors?
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What is the major factor controlling how levers work?
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Which of the following describes fascicle arrangement in a pennate muscle?
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What is the main factor that determines the power of a muscle?
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If a lever operates at a mechanical disadvantage, it means that the ________.
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What type of muscle assists an agonist by causing a like movement or by stabilizing a joint over which an agonist acts?
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In a pennate muscle pattern ________.
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What are the levers that operate at a mechanical advantage called?
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First-class levers ________.
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If L = load, F = fulcrum, and E = effort, what type of lever system is described as LEF?
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Both first- and second-class levers operate at a mechanical disadvantage.
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Although all skeletal muscles have different shapes, the fascicle arrangement of each muscle is exactly the same.
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Regardless of type, all levers follow the same basic principle: effort farther than load from fulcrum = mechanical advantage; effort nearer than load to fulcrum = mechanical disadvantage.
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Study Notes
Muscle Classification and Function
- Agonists are the primary muscles responsible for initiating and promoting specific movements.
- Synergists assist agonists in performing a movement and help stabilize joints during the action.
- Antagonists are muscles that oppose the action of agonists, providing balance and control.
- Fixators stabilize an origin of a prime mover by preventing unwanted movement.
Muscle Naming Criteria
- Muscles can be named based on location, attachment points, shape, and the number of origins.
- The number of origins indicated by terms like biceps (two), triceps (three), or quadriceps (four).
- Muscle names are not determined by whether they are controlled by the involuntary or voluntary nervous system.
Muscle Movement and Leverage
- Bones act as levers in movement; muscles pull on bones for movement, not push.
- During muscle contraction, the two articulating bones do not move equally; they experience different ranges of motion.
- Most skeletal muscles function as third-class levers, where effort is between the fulcrum and load.
Fascicle Arrangements
- Pennate muscles have short fascicles that attach obliquely to a central tendon, resembling a feather.
- Convergent muscles have a broad origin with fascicles converging towards a single insertion point, appearing fan-shaped.
- Circular muscles are found at the openings of the body, controlling the passage of substances.
Lever Systems
- First-class levers have the load at one end, the fulcrum at the opposite end, and effort in the middle, such as in raising the head.
- Second-class levers have the load between the fulcrum and effort, while third-class levers have effort between the fulcrum and load.
- Power levers operate at a mechanical advantage, enabling greater load lifting with less effort.
Mechanical Advantage and Disadvantage
- Mechanical advantages occur when the effort is farther from the fulcrum compared to the load.
- Factors determining muscle power include the total number of muscle cells available for contraction.
- False statements: Not all muscles operate at a mechanical disadvantage, and all skeletal muscles do not share the same fascicle arrangement.
Classification Summary
- Classification does not consider muscle fiber type as a categorization criterion.
- True or False: Muscles are only capable of pulling, indicating the nature of muscle contraction and movement.
- Postural muscles are not necessarily classified as synergists, challenging traditional perceptions of muscle roles.
Key Facts
- The hamstring muscles cross both the hip and knee joints, but do not promote knee rotation.
- Sternocleidomastoid muscles are named for their specific origin and insertion points.
- Fascicular arrangement in muscles greatly influences their function and efficiency during movement.
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Description
Test your knowledge on muscle classification, including agonists, synergists, antagonists, and fixators. Explore how muscles are named and their functions regarding movement and leverage. This quiz will help you understand the science behind muscle actions and their roles in the human body.
