Abstract
The hand represents one of the most remarkable expressions of humanization of the anterior limb. The anterior limb, at first ambulatory, underwent continuous evolution acquiring innumerable new functions. In the course of human evolution the hand has undergone continual structural and functional adaptations, characterized, among others, by enrichment of peripheral innervation and further development of the thumb. This development was accompanied by important changes in the brain and the relocation of the eyes, together allowing the muscle control and stereoscopic vision, necessary for a controlled grip. The anatomy of the hand is complex, intricate, and fascinating. Its integrity is absolutely essential for our everyday functional living. It is intimately correlated with the brain, both in the evolution of the species and in the development of the individual. Actually, we can state that we “think” and “feel” with our hands, hence, their contribution is essential to the mental processes of thought and feeling. The aim of this review is to evaluate the most typical hand quality, the prehensility and hence, the possibility of manoeuvring tools. Our attention is mainly focused on the hand anatomy and prehensility during pushing and pulling motions. In particular, our attention is directed toward the relationship existing between the hand prehensility and the volume of the object to be gripped. As an example, we use a grip of the paddle and, pushing and pulling motions during kayak paddling. Indeed, we are firmly convinced that the prehensility plays a crucial role not only in performing the stylistically correct paddling, but especially in realizing a more effective and powerful paddle stroke. This review highlights a great link existing between biomechanical and anatomical notions and sporting performance.
Highlights
When looking at children playing in the equipped playground or at school, we can observe most of the movements that they make. For their nature, explore the environment and test themselves continuously. They slide enthusiastically on the soft sand, make themselves spin at high speeds, invent dangerous exercises, but for one reason or another they do not let themselves hang down from the cross bar or swing from one cross bar to another
The fact that the cross bar is at a high distance from the ground can be excluded as well, since the kids would probably try to invent any possible way to reach it
When considering the reasons of this behaviour, one can notice that there is a huge discrepancy between the volume of the cross bar and the extreme limitations of the prehensility of the small child’s hand
Summary
When looking at children playing in the equipped playground or at school, we can observe most of the movements that they make. (c) Subterminal-lateral opposition prehensility: The palmar surface of the thumb is brought against the radial side of the middle phalanx This action allows one to hold small and flattened objects, but of a certain consistency, such as a coin or a piece of cardboard, between these two fingers. This kind of prehensility is normally used to hold the handle of working tools In this grip the thumb plays a key role as it is wrapped around the object in opposition to the other fingers. The strength of the prehensility is strongly conditioned by the diameter of the held object: this one is optimal when the thumb touches the index Another kind of classification of motion by Long et al [18] is “power grip”, which includes hook, squeeze, disc, and spherical grip; “precision grip”, which includes translation and rotation; and “pinch”. This observation is taken into account during the design of the tool handles and it allows their proper construction
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