Hand Function Lecture

Overview

• Hand function involves coordination of the entire upper extremity (shoulder, elbow, forearm, wrist, and hand).
• Key roles:
  • Shoulder: Positions the hand for tasks.
  • Elbow: Moves hand closer/farther from the body.
  • Forearm: Orients the palm for grasping and releasing objects.
  • Wrist: Final orientation & positioning for manipulation.
  • Digits (Fingers): Adapt to the demands of the task.

Components of Hand Function

• Motor Function: Involves muscle actions for grasping and manipulation.
• Sensory Function: Critical for effective hand function. Lack of sensation impairs hand operation.

Functional Position

• Wrist in slight extension.
• MCPs and PIPs in slight flexion.
• Thumb in opposition.
• DIPs may be slightly flexed or extended.

Types of Grips

Power Grip

• Requires more strength for holding objects.
• Examples:
  • Cylindrical Grip: Holding a bottle or bar.
  • Spherical Grip: Holding a ball or doorknob.
  • Hook Grip: Carrying a briefcase or suitcase.

Precision Grip

• Involves fine motor skills and accuracy.
• Examples:
  • Palmar Pinch: Thumb pad to finger pad (e.g., holding paper).
  • Lateral Pinch (Key Pinch): Thumb pad to side of index finger (e.g., holding a key).
  • Tip Pinch: Thumb tip to finger tip (e.g., picking up a needle).
  • Three Jaw Chuck/Palmar Pinch: Using thumb and first two fingers (e.g., holding a pen).
  • Lumbrical Grip: MCP flexion, PIP, and DIP extension (e.g., holding a hamburger or notepad).

Important Points

• Power grip strength relies heavily on the 4th and 5th digits.
• Preservation and enhancement of distal transverse arch are crucial.
• Intrinsic hand muscles play a significant role in precision grips.