Lecture: The Muscular System

Overview

• Completion of muscle tissue and contraction mechanisms.
• Introduction to the muscular system and its components.

Classification of Muscles

• Prime Movers (Agonists): Responsible for primary movement.
• Antagonists: Oppose movements, provide resistance, and refine motions.
• Synergists: Assist prime movers by adding force or reducing undesirable movements.
• Fixators: A type of synergist that immobilizes bones, aiding posture.
• Muscles can fulfill multiple roles depending on the motion.

Naming Criteria for Skeletal Muscles

1. Location: Example: Temporalis near the temporal bone.
2. Shape: Example: Trapezius is trapezoidal.
3. Size: Examples include gluteus maximus (large) and gluteus minimus (small).
4. Direction of Fibers:
   • Rectus: Parallel (e.g., rectus femoris).
   • Transversus: Perpendicular.
   • Oblique: Angled.
5. Number of Origins:
   • Biceps (two origins), Triceps (three), Quadriceps (four).
6. Location of Attachments: Origin to insertion (e.g., sternocleidomastoid).
7. Action: Examples include flexors, extensors, and adductors.

Muscle Shapes and Arrangements

• Circular Muscles: Concentric rings (e.g., around eyes and mouth).
• Convergent Muscles: Spread over a region, converge to a tendon (e.g., pectorals).
• Fusiform Muscles: Tapered at both ends (e.g., biceps).
• Parallel Muscles: Straight line, parallel to muscle's long axis (e.g., sartorius).
• Pennate Muscles: Oblique angles;
  • Unipennate: Muscle on one tendon side.
  • Bipennate: Muscle on both sides, feather-like.
  • Multipennate: Several feathers on the same tendon.
• Range of motion and power depend on muscle arrangement.
  • Parallel: Greater shortening, less power.
  • Oblique angles: Less shortening, more power.

Conclusion

• Brief introduction to specific muscles and their arrangement.
• Encouragement to familiarize with major muscles.
• Transition to learning about neurons and the nervous system.
• For further questions, contact the professor.