ABSTRACT
The thumb ray is shorter, more proximal, more mobile than the others ( Figure 17.1a ). It can project in front of the palm to oppose itself to the other four rays ( Figure 17.1b ). Opposition of the thumb is a complex movement that follows an arc of circumduction in a palmar and ulnar direction, allowing not only precision and power grip but also extensive contact between the pulp of the thumb and the pulps of the fingers, which are the sensory organs of touch.
