The Arsenal of our mobility

Motor capabilities of the human body is huge. In order to appreciate them fully, let us recall some information from mechanics.
Absolutely free physical body has six degrees of freedom: three mutually perpendicular direction (up-down, right-left, back and forth) and three mutually perpendicular axis of rotation, going in the same direction. The presence of these six degrees of freedom allows the body to move and rotate any manner, in all conceivable intermediate areas and axes. What is capable with this point of view, our body?
It is clear that the translational motion of a bone relatively articulated with her the other impossible. We are not able, for example, to separate arm from shoulder, broken elbow. Join our bones include the ability only rotational motions on various axes at certain angles. In different joint range of motion is not the same. There are joints uniaxial, biaxial and triaxial. Typical uniaxial joints are the articulation between the joints of our fingers. To biaxial include, for example, elbow, in which there are two types of movements (bending and rotation inward-outward), and the wrist joint, providing bending brush and cast-allocating it. Three-axle joints we have only two - hip and shoulder. As you can see, mobility of joints is superior to that of conventional technical devices. Hinges typically have only one axis of rotation. Maximum mobility in technology have biaxial connection - ball joint, Cam and rocker mechanisms.
If already in the device of the joints that have sometimes 2-3 degrees of freedom, provided a very large movement capabilities, the latter greatly increased due to the fact that we have in our body is not isolated pair of bones, and a number of kinematic chains with multiple serial links. Generally, there are 14 main kinematic parts of the body: head, torso and 3 for each of the four extremities (hands - hand, arm, shoulder and leg - foot, leg, thigh). Properties kinematic chain is very curious. There is a rule: the number of degrees of freedom peripheral chain link is the sum of the degrees of freedom of the preceding links. From here you can, for example, to see that our main working body - the hand is 7 degrees of freedom in relation to the body: on 2 axes in the wrist and elbow and 3-axis in the shoulder joints. In other words, brush our hands is not only absolutely free body (just 6 degrees of freedom). She has a redundant degree of freedom, i.e. a certain amount of reliability and saves the full scope of mobility even when the loss of one of movements in any joint. In recent decades, often vehemently debated about whether a machine to replace the human brain to become equivalent to him. It seems that completely replace the hand of man would be for the machine is also extremely challenging.