Published online by Cambridge University Press: 23 December 2009
Summary
A satisfactory description of human hand movements during the action of grasping was not available until the early 1980s. Kinematic parameters extracted from the displacements of anatomical landmarks located on the hand were used to differentiate between a transport component carrying the hand at the target location and a grasp component shaping the finger according to the object shape and size. These parameters, including the maximum grip aperture (MGA) are now currently adopted for testing vision for action in normal subjects, including in children at different stages of their visuomotor development, and in a wide range of pathological disorders affecting goal-directed movements.
Introduction: hand grasping movements before 1980
The hand is both a sensory and a motor organ. On the sensory side, in Sherrington's terms, it is the fovea of the somesthetic system, to the same extent as the center of the retina is the fovea of the visual system. The hand explores the haptic world by touching, grasping and manipulating objects in the same way as eye movements explore the visual world by displacing the retina between fixation points. The sensory and motor functions of the hand are complementary with one another. The movements of the fingers contribute to the exploration and perception of object shape and texture during manipulation and conversely sensory cues arising from the skin receptors contribute to the control of hand movements.
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