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Muscular System - Anatomy & Physiology

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Terms in this set (29)

  • What is a lever in the context of skeletal muscle movement?
    A lever is a rigid bar (bone) that moves around a fixed point called the fulcrum to produce movement.
  • Define the components of a lever system in the body.
    Effort is the applied force from muscle contraction, fulcrum is the joint, and load is the resistance such as bone or weight.
  • What is a first-class lever and give a body example?
    A first-class lever has the fulcrum between the effort and load. Example: lifting the head off the chest.
  • Describe a second-class lever and provide a body example.
    A second-class lever has the load between the fulcrum and effort. Example: standing on tiptoe.
  • What characterizes a third-class lever and give a common example?
    A third-class lever has the effort applied between the load and fulcrum. Most skeletal muscles are this type, e.g., biceps brachii.
  • What are fascicles in skeletal muscles?
    Fascicles are bundles of muscle fibers arranged in different patterns that influence muscle action.
  • Name the four types of fascicle arrangements.
    Parallel, convergent, pennate (uni-, bi-, multipennate), and circular.
  • What is the function of circular muscles?
    Circular muscles, or sphincters, surround body openings and control their opening and closing, e.g., orbicularis oris.
  • From which embryonic layer do muscles develop?
    Muscles develop from the mesoderm layer during embryonic development.
  • What are myotomes?
    Myotomes are groups of muscles innervated by a single spinal nerve, corresponding to embryonic somites.
  • List the four muscle groups based on embryonic development.
    Visceral organ musculature, pharyngeal arch muscles, axial muscles, and limb muscles.
  • What is the role of axial muscles?
    Axial muscles lie around the body axis and function to move the trunk and maintain posture.
  • Define prime mover (agonist) in muscle function.
    The prime mover is the muscle with the major responsibility for producing a specific movement.
  • What is an antagonist muscle?
    An antagonist opposes or reverses the action of the prime mover.
  • What is a synergist muscle?
    A synergist assists the prime mover by adding extra force or reducing unwanted movements.
  • What is a fixator muscle?
    A fixator is a type of synergist that stabilizes the origin of the prime mover by holding a bone firmly in place.
  • How are limb muscles organized in compartments?
    Limb muscles are divided into compartments by dense connective tissue; each compartment contains muscles with similar actions and is innervated by a single nerve.
  • What are the main actions of the anterior and posterior compartments of the arm?
    Anterior compartment muscles flex the shoulder or arm; posterior compartment muscles extend the shoulder or arm.
  • Name the four criteria used in naming skeletal muscles.
    Location, shape, relative size, and direction of fascicles or muscle fibers.
  • What does the term 'biceps' indicate about a muscle?
    'Biceps' indicates the muscle has two origins or heads.
  • Which cranial nerve innervates muscles of facial expression?
    Cranial nerve VII, the facial nerve, innervates muscles of facial expression.
  • Name the prime movers of mastication.
    The masseter and temporalis muscles are the prime movers of jaw closure.
  • Which nerve innervates the muscles of mastication?
    The mandibular division of cranial nerve V (trigeminal nerve) innervates mastication muscles.
  • What is the most important muscle of respiration?
    The diaphragm is the most important muscle of respiration.
  • Name the four flat muscles forming the lateral and anterior abdominal wall.
    External oblique, internal oblique, transversus abdominis, and rectus abdominis.
  • What is the function of the pelvic floor muscles?
    Pelvic floor muscles support pelvic organs and form the pelvic diaphragm.
  • Which muscles form the rotator cuff?
    Supraspinatus, infraspinatus, teres minor, and subscapularis.
  • What are the main muscles crossing the elbow joint for flexion?
    Biceps brachii, brachialis, and brachioradialis.
  • Which muscles are the powerful knee extensors?
    The quadriceps femoris group: rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius.