II. SURFACE ANATOMY - creases are present at each of the five (5) articulating areas:

1. wrist crease
2. thenar crease
3. distal interphalangeal crease
4. distal palmar crease
5. proximal interphalangeal crease

A. ARCHES OF THE HAND

1. Longitudinal arch - follows the arc which runs from the wrist through the third digit.
2. Transverse Arches
   • Proximal - arch over the wrist articulation.
   • Distal - arch over the metacarpophalangeal area.

B. FIXED UNIT OF THE HAND

1. consists of metacarpals II & III and the distal row of carpals. Has limited movement and is supported by tough intermetacarpal ligaments. This fixed unit forms a supporting structure for the remaining elements of the hand. "Central beam" allows for movement around it.

C. MOBILE UNIT OF THE HAND

1. composed of thumb, digits IV & V metacarpals and phalanges, along with the phalanges of the index and middle fingers. Allows for manipulation, grasping and strength.