Muscle Tissue Types and Structures
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Questions and Answers

What type of muscle contraction occurs when the length of the muscle changes while the tension remains constant?

  • Eccentric contraction
  • Isotonic contraction (correct)
  • Isometric contraction
  • Concentric contraction
  • Which muscle is considered the agonist during forearm extension?

  • Biceps brachii
  • Deltoid
  • Pectoralis major
  • Triceps brachii (correct)
  • What is the role of an antagonist muscle?

  • To produce the same movement as the agonist
  • To assist the agonist
  • To oppose the action of the agonist (correct)
  • To stabilize joints
  • Which connective tissue surrounds an entire muscle?

    <p>Epimysium</p> Signup and view all the answers

    Where is the insertion point of the muscle that has its origin in the thoracic vertebrae and extends to the humerus?

    <p>Humerus</p> Signup and view all the answers

    Which of the following actions is performed by the superior fibers of a muscle that originates from the occipital bone?

    <p>Elevation of the scapula</p> Signup and view all the answers

    What action does the pectoralis major muscle primarily perform?

    <p>Medial rotation of the arm</p> Signup and view all the answers

    Which feature distinguishes the origin from the insertion of a muscle?

    <p>Insertion is typically less stable</p> Signup and view all the answers

    What is the primary action of the triceps brachii?

    <p>Extend the forearm</p> Signup and view all the answers

    What is the origin of the long head of the triceps brachii?

    <p>Scapula</p> Signup and view all the answers

    Which muscle shares the same insertion point as the iliacus?

    <p>Psoas major</p> Signup and view all the answers

    Which head of the quadriceps femoris is responsible for flexing the thigh?

    <p>Rectus femoris</p> Signup and view all the answers

    What action does the biceps brachii perform as a prime mover?

    <p>Flexion of the forearm</p> Signup and view all the answers

    Which muscle primarily extends the leg at the knee?

    <p>Rectus femoris</p> Signup and view all the answers

    Which muscle originates from the os coxae and is involved in thigh flexion?

    <p>Psoas major</p> Signup and view all the answers

    What is the common insertion point for all heads of the quadriceps femoris?

    <p>Patella and tibia</p> Signup and view all the answers

    What is the main function of smooth muscle tissue?

    <p>To move substances along internal passageways</p> Signup and view all the answers

    Which connective tissue layer surrounds individual muscle fibers?

    <p>Endomysium</p> Signup and view all the answers

    How are skeletal muscle fibers characterized?

    <p>Multinucleate and striated</p> Signup and view all the answers

    What defines the sliding filament theory?

    <p>Myosin heads of thick filaments slide thin filaments along</p> Signup and view all the answers

    Which statement about skeletal muscles is correct?

    <p>They allow for body movement and posture maintenance</p> Signup and view all the answers

    What roles do tendons serve in the muscular system?

    <p>Attach muscles to bone or skin</p> Signup and view all the answers

    Which component is mainly involved in muscle contraction?

    <p>Myofilaments</p> Signup and view all the answers

    What does muscle tone refer to?

    <p>The constant tension in a resting muscle</p> Signup and view all the answers

    Which type of muscle tissue is responsible for the involuntary propulsion of blood?

    <p>Cardiac muscle</p> Signup and view all the answers

    What defines the function of myofibrils within muscle fibers?

    <p>They facilitate muscle contraction through interaction of thick and thin filaments</p> Signup and view all the answers

    Study Notes

    Muscle Tissue

    • There are three types of muscle tissue: smooth, cardiac, and skeletal
    • Smooth and cardiac muscle tissue are found in other organ systems
    • Skeletal muscles form the muscular system

    Smooth Muscle

    • Found in hollow organs
    • Responsible for movement of substances along internal passageways
    • Description: Elongated, single nucleus, arranged in a sheet-like structure, no striations

    Cardiac Muscle

    • Found in the walls of the heart
    • Responsible for pumping blood
    • Description: Branching cells separated by intercalated discs, striated, single nucleus

    Skeletal Muscle

    • Attached to bones, cartilage, and skin
    • Responsible for voluntary movement
    • Description: Long, cylindrical, multinucleate, striated

    ### Skeletal Muscle: Structure

    • Muscle fibers are organized into bundles called fascicles
    • Muscle fibers contain myofibrils
    • Myofibrils are composed of myofilaments

    Connective Tissue Coverings

    • There are three layers of connective tissue that surround muscles: endomysium, perimysium, and epimysium
    • Endomysium: Surrounds each muscle fiber
    • Perimysium: Surrounds fascicles
    • Epimysium: Surrounds the entire muscle

    Myofilaments

    • Composed of thick and thin filaments
    • Thick filaments: Comprised of myosin molecules with heads and tails; myosin heads bind to thin filaments
    • Thin filaments: Mainly two strands of filamentous actin (F-actin) twisted around each other; contain myosin binding sites
    • Sarcomere: the functional unit of thick and thin filaments

    Neuromuscular Junction

    • One motor neuron controls each muscle fiber
    • Nerve impulses travel from the nervous system to the muscle

    Sliding Filament Theory

    • Myosin heads of thick filaments slide along thin filaments
    • This shortens the sarcomere, not the filaments themselves

    Muscle Attachments

    • Tendons: Merge connective tissues at muscle ending and attach bones, skin, or other muscles
    • Aponeurosis: Thin, flattened connective tissue attachment
    • Muscles generally cross joints
    • Insertion: Bone which moves the most
    • Origin: Bone which moves the least

    Muscle Function

    • Muscle tone: Constant tension in resting muscle; motor units are stimulated randomly
    • Isometric contraction: Length remains constant; tension changes
    • Isotonic contraction: Tension remains constant; length changes

    Muscle Groups

    • Agonist: Produces movement; also known as the "prime mover"
    • Antagonist: Opposes the action of the agonist
    • Synergist: Assists the agonist in performing its action; includes stabilizing fixators

    Specific Muscles

    • Trapezius:
      • Origin: Occipital bone, C7, and thoracic vertebrae
      • Insertion: Scapula and clavicle
      • Action: Elevates, retracts, or depresses the scapula depending on fiber contraction
    • Pectoralis Major:
      • Origin: Clavicle, sternum, and cartilage of ribs
      • Insertion: Humerus
      • Action: Adducts arm, medially rotates, and aids in flexion and pull ribs upwards
    • Latissimus Dorsi:
      • Origin: Thoracic, lumbar vertebrae, and illium
      • Insertion: Humerus
      • Action: Extends, adducts, and medially rotates arm
    • Deltoid:
      • Origin: Clavicle and scapula
      • Insertion: Humerus
      • Action: Abducts arm (prime mover), flexes and extends arm depending on fiber contraction
    • Biceps Brachii:
      • Origin: Two heads on the scapula
      • Insertion: Radius
      • Action: Flexes forearm (prime mover) and supinates forearm
    • Triceps Brachii:
      • Origin: Long head on scapula, lateral and medial heads on humerus
      • Insertion: Ulna
      • Action: Extends forearm (prime mover); stabilizes shoulder joint

    Hip Flexors

    • Iliacus:
      • Origin: Os coxae (ilium) and sacrum
      • Insertion: Femur
      • Action: Flexes thigh (prime mover)
    • Psoas Major:
      • Origin: Lumbar vertebrae and T12
      • Insertion: Femur
      • Action: Flexes thigh (prime mover)
      • Other actions: Flexes vertebral column laterally, maintains posture
    • Gluteus Maximus:
      • Origin: Os coxae (ilium), sacrum, coccyx
      • Insertion: Femur
      • Action: Extends thigh (prime mover)
      • Other actions: Abducts and laterally rotates thigh
    • Biceps Femoris:
      • Origin: Long head: os coxae (ischium); Short head: femur
      • Insertion: Fibula and tibia
      • Action: Flexes leg at the knee (prime mover)

    Knee Extensors

    • Quadriceps femoris:
      • Origin:
        • Rectus femoris: os coxae (ilium)
        • Vastus lateralis: femur
        • Vastus medialis: femur
        • Vastus intermedius: femur
      • Insertion: Patella and tibia
      • Action:
        • All heads: Extends leg at knee (prime mover)
        • Rectus femoris only: Flexes thigh

    Walking Muscles

    • Muscles work together to produce opposing movements, allowing for walking forward
    • Hip Flexors: Initiate forward movement of the leg
    • Knee Extensors: Push off and extend the leg back
    • Hip Extensors: Keep the thigh extended
    • Knee Flexors: Prepare the leg for the next step

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    Description

    Explore the three types of muscle tissue: smooth, cardiac, and skeletal. This quiz will cover their characteristics, structures, and functions within the human muscular system. Test your knowledge on the unique roles and structures of each muscle type.

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