The metacarpal’s transverse arch

There are three types of levers distinguished by the position of their elements: power, resistance, fulcrum.  Human body levers are almost all of third species, ie in them the fulcrum is positioned between power and resistance.  The latin word fulcrum means to support: it is the point from which a lever moves.  The fulcrum is a motionless point from which levers operate and acquire their power.  The fulcrum itself exerts a force which is called the “reaction force of the fulcrum” because it reacts to the action of resistance and power.  The fulcrum must be able to withstand the efforts to which it is subjected as it "supports" the movement.  Without the stability of the fulcrum, the action of the levers is poorly effective or even compromised.  

The finger is also a third species lever: the piano key is resistance, the finger is power, the metacarpal is fulcrum.  If we carefully observe the structure of the hand we can notice that the 2nd and 3rd metacarpals are fixed, while the 4th and 5th are mobile.  It is as if the hand is divided into two parts, in order to have two distinct functions.  Fixed metacarpals allow precision and give a lot of stability to the system, while mobile metacarpals allow a global grip on the hands, allowing to clench one’s fist.  This turns into an obvious mechanical disadvantage regarding piano technique.  Therefore it becomes necessary to compensate for this mechanical disadvantage and to ensure that the fulcrums of the 4th and 5th fingers also have their stability, in order to allow the levers to function optimally.  

Metacarpals are kept compact by a deep transverse ligament which, if put under tension, will create stabilization of the ulnar metacarpals (4th and 5th finger).  Furthermore, through this action, the formation of the transverse arch will be created simultaneously.  This is made possible thanks to the abduction of the thumb and to the opening of the ulnar part.  

Isometric exercises are the most effective way to develop muscle tone.  A specific isometric exercise to develop the thumb abduction movement is the following: open your thumb and contrast the movement with the other hand that will exert a force in the opposite direction, keep your posture for no more than six seconds.  The same isometric exercise can also be performed to develop the opening movement of the ulnar part.  Finally, it is very important that these movements must be as isolated as possible, trying not to contract other muscles of the hand.

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