Lecture on the Muscular System

Overview

• Discussion on the muscular system and muscle contraction processes.
• Introduction to the classification of muscles and their names.

Muscle Classification by Function

• Prime Movers (Agonists):
  • Primary responsibility for producing motion.
• Antagonists:
  • Oppose particular movements.
  • Provide resistance and enable delicate motions.
• Synergists:
  • Assist prime movers.
  • Contribute additional force or reduce undesirable movements.
  • Can act as stabilizers.
• Fixators:
  • Type of synergists that immobilize bones, aiding in posture maintenance.
• A muscle can exhibit multiple roles depending on the motion.

Naming of Skeletal Muscles

• Muscle Location:
  • Example: Temporalis muscle near the temporal bone.
• Muscle Shape:
  • Example: Trapezius muscle is trapezoidal.
• Muscle Size:
  • Terms like maximus (large), minimus (small), longus (long), and brevis (short).
  • Examples: Gluteus maximus and gluteus minimus.
• Direction of Muscle Fibers:
  • Rectus (parallel), transversus (perpendicular), and oblique (angled).
  • Example: Rectus femoris muscle.
• Number of Origins:
  • Biceps (two), triceps (three), quadriceps (four).
• Location of Attachment:
  • Points of origin and insertion, e.g., sternocleidomastoid muscle.
• Type of Motion:
  • Flexor, extensor, adductor, etc.

Muscle Shapes and Arrangements

• Circular Muscles:
  • Concentric rings, e.g., muscles around eyes and mouth.
• Convergent Muscles:
  • Spread out but converge on a tendon, e.g., pectorals.
• Fusiform Muscles:
  • Taper to a tendon on both ends, e.g., biceps.
• Parallel Arrangement:
  • Fascicles parallel to long axis, e.g., sartorius muscle.
• Pennate Muscles:
  • Fascicles at oblique angles, various types:
    • Unipennate: Muscle on one side of tendon.
    • Bipennate: Muscle on both sides, resembling a feather.
    • Multipennate: Several feathers into the same tendon.

Muscle Motion

• Skeletal muscles contract by about 30%.
• Parallel fibers: Shorten most, but with less power.
• Oblique fibers: Shorten less, but generate more power.

Conclusion

• Overview of important muscles in the body using images.
• Encouragement to memorize muscles if needed, especially for medical fields.
• Transition to learning about neurons and the nervous system next.