Questions and Answers
What action do the antagonist muscles of the gluteus medius produce and on which side of the hip joint are they located?
Hip adductors produce adduction and are located on the medial side of the hip joint.
What do the names of the muscles adductor brevis, quadriceps femoris, tibialis anterior, and iliacus indicate?
Adductor brevis is a small muscle for adduction; quadriceps femoris has four heads; tibialis anterior lies in front of the tibia; iliacus overlies the iliac bone.
How do you identify whether a muscle is convergent, circular, fusiform, parallel, or pennate?
Which of the three lever systems involved in muscle mechanics is the fastest?
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When using a lever to pry an old fence post out of the ground, should the fulcrum be closer to you or the post?
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What facial muscles did Mario use to raise his eyebrows and wink?
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How can the deltoid muscles both extend and flex the arm?
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Which thenar muscle does not have an insertion on the bones of the thumb?
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What muscles contract to make a 'sad clown's face'?
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What are prime movers?
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What is an agonist?
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What is an antagonist?
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What is a synergist?
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What are fixators?
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What is a power lever?
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What is mechanical advantage?
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What are speed levers?
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What is mechanical disadvantage?
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What is a first-class lever?
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What is a second-class lever?
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What is a third-class lever?
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Study Notes
Muscle Action and Antagonism
- The gluteus medius, located laterally, abducts the thigh while its antagonists, the hip adductors, are positioned on the medial side to produce adduction.
Muscle Naming Criteria
- Adductor brevis: Indicates a small muscle responsible for thigh adduction.
- Quadriceps femoris: Named for its four heads, aligning with the femur.
- Tibialis anterior: Located in front of the tibia.
- Iliacus: Positioned above the iliac bone.
Muscle Identification Types
- Understand the differences in muscle types: convergent, circular, fusiform, parallel, and pennate based on structure and function.
Lever Systems in Muscle Mechanics
- Third-class levers operate the fastest among the three types—first, second, and third-class levers.
Lever and Mechanical Advantage
- For prying an old fence post, position the fulcrum closer to the post for mechanical advantage, requiring less force to lift the load.
Facial Muscles in Expression
- The frontal belly of the epicranius raises eyebrows; the orbicularis oculi is responsible for winking.
Deltoid Muscle Actions
- The deltoid muscle can both flex and extend the arm due to its broad origin and distinct anterior and posterior fiber contractions.
Thenar Muscles
- The opponens pollicis is the only thenar muscle that does not attach to the thumb bones.
Facial Expression Muscles
- To create a "sad clown's face," engage the platysma, depressor anguli oris, and depressor labii inferioris.
Functional Muscle Roles
- Prime movers: Major force producers for specific movements.
- Agonist: Binds to receptors to stimulate a response.
- Antagonist: Opposes or reverses a prime mover's action.
- Synergist: Assists a prime mover while preventing unwanted motion.
- Fixators: Stabilize bone or muscle origins during movement.
Lever Types and Mechanical Advantage
- Power lever: Operates with mechanical advantage, requiring less effort to move a load.
- Mechanical advantage: Output force to input force ratio in a machine.
- Speed lever: Operates at mechanical disadvantage for rapid movement.
- Mechanical disadvantage: The load is further from the fulcrum than the effort applied, necessitating greater effort to move the load.
- First-class lever: Muscle and resistive forces act on opposite sides of the fulcrum.
- Second-class lever: The load is positioned between the fulcrum and input force, not changing the input force's direction.
- Third-class lever: The effort lies between the fulcrum and the resistance, providing quicker movements.
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Description
This quiz explores key concepts related to muscle action, naming criteria, types of muscle identification, and lever systems in muscle mechanics. Understand the roles of various muscles and how their functions relate to movement and mechanical advantage.