Ch 10: Muscle Movement Fundamentals

Chapter Overview

  • Chapter 10 focuses on the muscular system and its origins, definitions, and muscle actions.
  • Every muscle discussed will serve as an organ within this system.

Key Definitions

  • Origin: The immovable part of a muscle, serving as an anchor attached to stationary bones.
  • Insertion: The movable part of a muscle where it attaches to a movable bone.
  • Notation: Origin is often abbreviated as O and insertion as I.

Biceps Brachii Example

  • Biceps Brachii:
    • Origin: Located at the coracoid process of the scapula.
    • Insertion: Attaches to the radius.
    • Action: When contracted, it pulls the radius upwards to flex the forearm.

Muscle Relationships

  • Actions:
    • Agonists (Prime Movers): Muscles that provide the majority of the force for movement (e.g., biceps brachii).
    • Antagonists: Muscles that oppose or reverse movements (e.g., triceps brachii extends the arm).
    • Synergists: Muscles that assist prime movers or stabilize joints during movement.

Joint Movements and Actions

  • Flexion: Decreasing angles between joints or moving a limb anteriorly (e.g., bending the elbow).
  • Extension: Increasing angles between joints; can mean moving a limb posteriorly to return to anatomical position.
  • Hyperextension: Movement beyond the anatomical position, often resulting in injury (e.g., hyperextending a knee).
Specific Joint Movements
  • Abduction: Moving a limb away from the torso (e.g., swinging arms away).
  • Adduction: Moving a limb towards the torso (e.g., bringing arms back to center).
  • Rotation: Turning a bone on its axis (e.g., neck rotation, forearm rotation).
  • Elevation: Raising a joint (e.g., shrugging shoulders).
  • Depression: Lowering a joint (e.g., relaxing shoulders).
  • Protraction: Moving a joint forward (e.g., jutting out the jaw).
  • Retraction: Pulling a joint back (e.g., retracting the jaw).
Movements of the Foot
  • Inversion: Sole of foot faces medially (e.g., rolling the foot inward).
  • Eversion: Sole of foot faces laterally (e.g., rolling the foot outward).
  • Dorsiflexion: Pointing the toes up (e.g., walking on heels).
  • Plantar Flexion: Pointing the toes down (e.g., walking on tiptoes).

Arm Hand Movements

  • Supination: Rotation of the forearm so palm faces anteriorly.
  • Pronation: Rotation of the forearm so palm faces posteriorly.
  • Opposition: Thumb movement allowing for thumb-to-finger contact, crucial for dexterity.

Summary of Terms for Movement

  • Flexion/Extension: Decrease/Increase angle between joints.
  • Hyperextension: Beyond normal range, typically an injury.
  • Abduction/Adduction: Movement away or towards the midline.
  • Elevation/Depression: Raising or lowering a joint.
  • Protraction/Retraction: Moving a body part forward or back.
  • Inversion/Eversion: Foot mechanics facing inward or outward.
  • Dorsiflexion/Plantar Flexion: Foot movements upward or downward.
  • Supination/Pronation: Wrist movements turn palm up or down.

Conclusion

  • Understanding the origin, insertion, and actions of muscles is key to mastering the muscular system's functionality and moving effectively.