Muscle Attachments and Actions: Key Points

Introduction

• Over 600 muscles in the human body.
• Learning involves memorizing muscle attachments and their roles in joint movements.
• Uses specialized vocabulary common in anatomy studies.

Muscle Attachments

• Origins: Attachment points on bones that remain immobile during an action.
• Insertions: Attachment points on bones that move during the action.
• Example: Triceps brachii has one insertion on the ulna and three origins — two on the humerus and one on the scapula.

Muscle Actions

• Muscles act on synovial joints to create movement.
• Common movement terms:
  • Flexion: Decreasing the angle between two bones (e.g., bending the elbow).
  • Extension: Increasing the angle between two bones (e.g., straightening the elbow).
  • Abduction: Moving away from the body's midline (e.g., raising the arm to the side).
  • Adduction: Moving toward the body's midline (e.g., lowering the arm).
  • Pronation: Rotating the forearm so the palm faces backward/down.
  • Supination: Rotating the forearm so the palm faces forward/up.
  • Elevation: Moving a body part up (e.g., closing the mouth).
  • Depression: Moving a body part down (e.g., opening the mouth).
  • Protraction: Moving a bone forward without angle change (e.g., jutting the jaw).
  • Retraction: Moving a bone backward without angle change.
  • Inversion: Turning the sole of the foot inward.
  • Eversion: Turning the sole of the foot outward.
  • Dorsiflexion: Bringing the foot upward toward the shin.
  • Plantar flexion: Depressing the foot.

Muscle Roles in Actions

• Prime Movers/Agonists: Main muscles driving the action (e.g., triceps brachii in elbow extension).
• Antagonists: Muscles that oppose the prime mover by providing resistance or reversing the movement.
• Synergists: Muscles assisting the prime mover.
• Stabilizers: Muscles that keep bones immobile when necessary (e.g., back muscles for posture).

Additional Resources

• External sources like "BBC Bitesize" and "Geeky Medics" for further reading on muscle contractions and movements.
• Related articles on muscle types and pathologies available for deeper exploration.

These notes provide a comprehensive overview of muscle attachments, actions, and key terminologies used in understanding muscular movements.