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Questions and Answers
What is the main characteristic that distinguishes intrinsic muscles from extrinsic muscles?
What is the main characteristic that distinguishes intrinsic muscles from extrinsic muscles?
What is the term for the result of muscle contraction at a joint?
What is the term for the result of muscle contraction at a joint?
What is the purpose of antagonistic muscles in aggregate muscle action?
What is the purpose of antagonistic muscles in aggregate muscle action?
What is the importance of innervation in muscle function?
What is the importance of innervation in muscle function?
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What is the term for the range of muscle fiber length from fully stretched to fully contracted?
What is the term for the range of muscle fiber length from fully stretched to fully contracted?
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What is the purpose of tendons in the muscle structure?
What is the purpose of tendons in the muscle structure?
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What is the term for the part of the muscle containing contractile fibers?
What is the term for the part of the muscle containing contractile fibers?
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What is an example of muscles sharing common tendons?
What is an example of muscles sharing common tendons?
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What is the main function of an aponeurosis?
What is the main function of an aponeurosis?
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What is the term for fascia that holds tendons in place to prevent bowstringing?
What is the term for fascia that holds tendons in place to prevent bowstringing?
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What occurs when fascia compartments in the lower leg become too tight?
What occurs when fascia compartments in the lower leg become too tight?
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What is the proximal attachment of a muscle called?
What is the proximal attachment of a muscle called?
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What happens when a muscle contracts without voluntary control?
What happens when a muscle contracts without voluntary control?
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What is the result of the biceps brachii contraction when the scapula is stabilized?
What is the result of the biceps brachii contraction when the scapula is stabilized?
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What is the purpose of stabilizing muscles in the body?
What is the purpose of stabilizing muscles in the body?
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What is the characteristic of the insertion of a muscle?
What is the characteristic of the insertion of a muscle?
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Study Notes
Intrinsic and Extrinsic Muscles
- Intrinsic muscles: small muscles located within the same body region, e.g. muscles in the hands and feet.
- Extrinsic muscles: muscles that originate in one body part and end in another, often crossing multiple joints and performing multiple actions.
Muscle Actions and Joint Actions
- Muscle action: the result of muscle contraction at a joint, e.g. the bicep brachii flexes the elbow.
- Joint actions: movements such as flexion, extension, abduction, adduction, internal rotation, and external rotation.
- Aggregate muscle action: multiple muscles working together to produce movement, including stabilization by antagonistic muscles, e.g. wrist flexion.
Muscle Innervation and Amplitude
- Innervation: the nerve supply to a muscle, crucial for muscle function, especially during injuries or diseases.
- Amplitude: the range of muscle fiber length from fully stretched to fully contracted.
Muscle Structure and Tendons
- Gaster (belly/body): the part of the muscle containing contractile fibers.
- Tendons: dense, fibrous connective tissue that connects muscle to bone, non-contractile, providing attachment points.
Aponeurosis and Fascia
- Aponeurosis: a flattened tendon, e.g. plantar fascia, IT band, binding, wrapping, and connecting muscles to other structures.
- Fascia: connective tissue that organizes, separates, or groups muscles and other structures, forming retinaculum around joints.
Origin and Insertion
- Origin: the proximal attachment of a muscle (closest to the midline), least movable part or attachment of the muscle.
- Insertion: the distal attachment of a muscle (farthest from the midline), most movable part.
Contraction Mechanics
- Contraction: muscles contract toward the center, pulling both ends.
- Stabilization: stabilizing muscles prevent unwanted movement, allowing specific joint actions.
- Electrical Stimulation: muscles contract toward the center when stimulated electrically without voluntary control.
- Stabilization Importance: other muscles stabilize parts of the body to direct movement efficiently.
When a Muscle Contracts
- Pulls both ends toward the gaster.
- If neither bone is stabilized, both bones move toward each other.
- Typically, one bone is more stabilized, and the less stabilized bone moves toward the more stabilized bone.
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Description
Learn about the different types of muscles, including intrinsic and extrinsic muscles, their definitions, characteristics, and examples.
