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Anatomy & Physiology: Skeletal Muscle Structure and Function

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Terms in this set (31)

  • Skeletal muscle fiber
    Specialized long, thin, multinucleated cells that compose skeletal muscles.
  • Endomysium
    Thin layer of extracellular matrix surrounding each muscle fiber.
  • Fascicle
    Bundle of 10–100 muscle fibers surrounded by perimysium.
  • Epimysium
    Connective tissue sheath surrounding all fascicles in a muscle.
  • Fascia
    Most superficial connective tissue sheath, continuous with epimysium.
  • Tendon
    Connective tissue attaching muscle to bone, transmitting force for movement.
  • Parallel fascicle pattern
    Fascicles run parallel to the muscle’s length, e.g., Sartorius.
  • Pennate fascicle pattern
    Fascicles attach to tendon at an angle, resembling a feather; includes unipennate, bipennate, multipennate.
  • Agonist (Prime Mover)
    Main muscle responsible for producing a specific movement.
  • Antagonist muscle
    Muscle that opposes the action of the agonist, allowing controlled movement.
  • Synergist muscle
    Assists the agonist by stabilizing and guiding movement.
  • Fixator muscle
    Stabilizes the origin of the agonist to increase movement efficiency.
  • Muscle origin
    Fixed attachment point of a muscle, usually proximal.
  • Muscle insertion
    Moveable attachment point of a muscle; moves toward origin during contraction.
  • First-class lever in the body
    Fulcrum is between load and force, e.g., atlanto-occipital joint.
  • Second-class lever in the body
    Load is between fulcrum and force, e.g., metatarsophalangeal joints.
  • Third-class lever in the body
    Force is between fulcrum and load, e.g., elbow joint.
  • Mechanical advantage
    Small force moves a large load when fulcrum is close to load.
  • Muscle naming by size
    Terms like brevis (short), longus (long), vastus (large) describe muscle size.
  • Muscle naming by function
    Names like flexor, extensor, adductor describe muscle action.
  • Epicranius muscle action
    Elevates eyebrows and forehead.
  • Orbicularis oculi action
    Closes the eyelids.
  • Masseter muscle action
    Elevates the mandible for chewing.
  • Diaphragm muscle function
    Contracts to increase thoracic volume during inspiration.
  • Rectus abdominis action
    Flexes the trunk and forms the 'six-pack'.
  • Levator ani muscle function
    Supports the pelvic floor.
  • Serratus anterior action
    Protracts and rotates the scapula.
  • Deltoid muscle action
    Abducts, flexes, and extends the arm at the shoulder.
  • Biceps brachii action
    Flexes and supinates the forearm.
  • Triceps brachii action
    Extends the forearm at the elbow.
  • Tibialis anterior action
    Dorsiflexes and inverts the foot.