Anatomy and Movements of the Hand Joints

Overview

• The hand has multiple joints and bones.
• Key joints include:
  • Carpometacarpal (CMC) Joint
  • Metacarpophalangeal (MCP) Joint
  • Proximal Interphalangeal (PIP) Joint
  • Distal Interphalangeal (DIP) Joint

Carpometacarpal (CMC) Joint

• Bones Involved: Metacarpal bones, Capitate, Trapezium
• Movement Characteristics:
  • Second and third CMC joints: Limited movement
  • Thumb CMC, Ring Finger, and Little Finger CMC: More mobile
• Thumb CMC Joint:
  • Saddle joint allowing various movements
  • Movements:
    • Palmar Abduction/Abduction: Moving thumb up towards the ceiling
    • Radial Abduction/Extension: Moving thumb outward/away
    • Flexion: Bending thumb towards the palm
    • Opposition: Thumb pad touching the pads of other fingers
  • Terminology can be confusing due to variations in textbooks

Metacarpophalangeal (MCP) Joint

• Joint Structure: Convex with concave joint surfaces
• Stability:
  • Relies on collateral ligaments
  • Radial collateral ligament on the radial side
  • Ulnar collateral ligament on the ulnar side
  • Ligaments are tight at 90° flexion
• Clinical Importance:
  • Post-injury, positioning MCP joints in 90° flexion is crucial to maintain ligament length and function
  • Proper positioning prevents shortening of ligaments, ensuring functional range of motion
• Movements:
  • Flexion and Extension
  • Abduction and Adduction
  • Some individuals may have hyperextension capability

Interphalangeal (IP) Joints

• Types:
  • Proximal Interphalangeal (PIP) Joint
  • Distal Interphalangeal (DIP) Joint
  • Thumb has a single IP joint
• Movements:
  • Flexion and Extension only
• Stability: Dependent on collateral ligaments