ANA1 L7 Muscular

• What do skeletal muscles generate, modulate, and transmit force for?


  To stabilize or move skeletal structures
• What is the definition of posture?


  Balanced competing forces
• What is the definition of movement?


  Unbalanced competing forces
• What are the three types of muscle tissue?

  • Skeletal Muscle
  • Cardiac Muscle
  • Smooth Muscle
• How are skeletal muscles classified in terms of striation?


  Skeletal and cardiac muscles are striated, while smooth muscle is unstriated
• What type of control is skeletal muscle under?


  Voluntary control (somatic nervous system)
• What type of control is cardiac muscle under?


  Involuntary control (autonomic nervous system)
• What type of control is smooth muscle under?


  Involuntary control (autonomic nervous system)
• What is the structure of skeletal muscle fibers?


  Large, long, unbranched, cylindrical fibers
• What is the structure of cardiac muscle fibers?


  Branching, anastomosing shorter fibers connected end to end by complex junctions
• What is the structure of smooth muscle fibers?


  Single or agglomerated small, spindle-shaped fibers
• What is the primary function of skeletal muscle?


  To move or stabilize bones and other structures
• What is the primary function of cardiac muscle?


  To pump blood
• What is the primary function of smooth muscle?


  To move/propel substances or restrict flow
• What are the parts of skeletal muscle and their descriptions?


  • Composed of thousands of muscle fibers
  • Enclosed by epimysium
  • Fasciculi: Bundles of muscle fibers, enclosed by perimysium
  • Muscle fiber: A.k.a muscle cell, enclosed by endomysium
• What is the length range of muscle fibers?


  From a few mm to 1-50 cm
• What is the diameter range of muscle fibers?


  10-100 micrometers
• What is the sarcolemma?


  The cell membrane of the muscle fiber
• What is the function of the sarcoplasmic reticulum?


  It has a relatively high concentration of Ca$^{2+}$, which plays a major role in muscle contraction
• What are myofibrils and their composition?


  • Threadlike structures in muscle fibers
  • Composed of actin myofilaments and myosin myofilaments
• What are sarcomeres?


  They are the smallest portion of skeletal muscle capable of contracting
• What happens when sarcomeres shorten?


  The myofibrils shorten, causing muscle fiber contraction
• What are the components of actin myofilaments?


  • Actin
  • Troponin
  • Tropomyosin
• What do myosin myofilaments resemble?


  Bundles of minute golf clubs
• What is a cross-bridge in muscle contraction?


  It is formed when myosin binds to actin
• What are the parts of a sarcomere?


  • Z Line: Boundaries for the sarcomere
  • A Band: Extends over myosin and part of actin
  • I Band: Areas with only actin
  • H Zone: Central portion of myosin without actin overlap
  • M Line: Central portion of H zone connecting myosin filaments
• What are contractile proteins in a sarcomere?


  Actin and myosin
• What are non-contractile proteins in a sarcomere?


  Titin and desmin
• What are the classifications of skeletal muscle based on fasciculi arrangement?

  • Fusiform
  • Pennate
  • Circular or sphincteral
  • Multi-headed
  • Flat/parallel
  • Quadrate
• What is the characteristic of fusiform muscles?


  Fibers running parallel to one another and to the central tendon
• What is the characteristic of pennate muscles?


  Fibers approach their central tendon obliquely
• What is an example of a fusiform muscle?


  Rectus abdominis
• What is an example of a unipennate muscle?


  Flexor pollicis longus (FPL)
• What is an example of a bipennate muscle?


  Gastrocnemius
• What is an example of a multipennate muscle?


  Deltoid
• What is an example of a circular or sphincteral muscle?

  Orbicularis oris
• What is a multi-headed muscle?


  A muscle with more than one head or attachment
• What is an example of a multi-headed muscle?

  Biceps brachii
• What is an example of a flat/parallel muscle?

  External oblique
• What is an example of a quadrate muscle?


  Pronator quadratus