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Outline

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  • Skeletal Muscle Structure

    Properties of Muscular Tissue

    The Muscle Fiber

    Slow- and Fast-Twitch Fibers

    Muscular Attachment

    Structural Classification of Muscles on the Basis of Fiber Arrangement

    Effect of Muscle Structure on Force and Range of Motion

  • Skeletal Muscle Function

    Line of Pull

    Types of Contraction

    Influence of Gravity

    Length-Tension Relationship

    Force-Velocity Relationship

    Stretch-Shortening Cycle

  • Coordination of the Muscular System

    Roles of Muscles

    Cocontraction

    Action of Biarticular Muscles

    Types of Bodily Movements

  • Methods of Studying the Actions of Muscles

    Conjecture and Reasoning

    Dissection

    Inspection and Palpation

    Models

    Muscle Stimulation

    Electromyography (EMG)

    Imaging

  • Muscular Analysis

  • Laboratory Experiences

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Objectives

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At the conclusion of this chapter, the student should be able to:

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  1. Describe the structure and properties of the whole muscle, fast- and slow-twitch muscle fiber, and the myofibril.

  2. Explain how the relationship of the muscle's line of pull to the joint axis affects the movement produced by the muscle.

  3. Describe the relationship between the skeletal muscle's fiber arrangement and its function.

  4. Define the roles a muscle may play (agonist, antagonist, and synergist), and explain the cooperative action of muscles in controlling joint actions by naming and explaining the muscle roles in a specified movement.

  5. Define the types of muscular contraction (concentric, eccentric, and static), and name and demonstrate each type of action.

  6. Demonstrate an understanding of the influence of gravity and other external forces on muscular action by correctly analyzing several movement patterns in which these forces influence the muscular action.

  7. Describe the various methods of studying muscle action, citing the advantages and disadvantages of each method.

  8. State the force-velocity and length-tension relationships of muscular contraction, and explain the significance of these relationships in static and dynamic movements.

  9. Identify the muscle groups active in a variety of motor skills.

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Body parts are moved by external or internal forces. The internal force responsible for the movement and positioning of the bony segments of the body is the action of skeletal muscles. These muscles are able to serve this function because they can contract, they are attached to the bones, and they cross a joint. In addition, they are constructed of bundles of striated muscle fibers, which differ in both structure and function from the highly specialized cardiac muscle and from the smooth muscle of blood vessels, digestive organs, and urogenital organs.

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Skeletal Muscle Structure

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Properties of Muscular Tissue

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The properties of striated muscle tissue are extensibility, elasticity, and contractility. The first two enable a muscle to be stretched like an elastic band and, when the stretching force is discontinued, to return again to its normal resting length. Tendons, which are simply continuations of the muscle's connective tissue, also possess these properties. Contractility, the ability to shorten and produce tension at its ends, is a unique property possessed by muscle tissue only. The average muscle fiber can shorten to approximately one-half its resting ...

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