It is the white part of the muscle, being in his interior little sanguineous circulation and great amount of nervous completions. The muscular belly is located in central part of the muscle, between its sinews of origin and insertion. She is red, very variable in length and volume (contraction/relaxation) and with great amount of blood vessels. Of what a muscle is made up is formed by the union of thousands to million (following the muscle) of its basic cellular units, the muscular fibers. These are united as much along as to wide it, forming small fiber groups called muscular fascicles or beams, also combined one next to the other as well until forming the muscle in himself.
The fact to separate fibers in different fascicles is a preventive method facing a possible injury. If the muscle were formed by a single fascicle, in case of breakage it would remain totally disabled to realise his function motorboat. It is possible to say that the muscular fiber is divided in still smaller functional structures, mofibrillas. We will not enter detail, since we would turn aside ourselves of our objective. How a muscle is contracted Another actor, the nerve. A muscle is contracted thanks to an electrical stimulus, a nervous impulse. The contraction order comes from the central nervous system, formed by encfalo and spinal marrow. This stimulus takes place of voluntary way, when we want to generate a movement, or involuntary, as a result of a reflection (generally defensive), but sometimes also by a nervous anomaly, causing what we called contractura (maintained involuntary contraction in the time).
This anomaly can come from two sources. A physiological one, in that the nerve has been irritated, injured or compressed by some other structure of the body (a joint, a muscle, an inflammation, ). Another emotional one, as escape route of an excessive nervous activity, generating stimulus of contraction to different muscles from the body, generally near the central nervous system (head, neck and back). In the contraction of the muscle also the chemical equilibrium of its cells is transcendental. As much for the contraction in himself as for the transmission of the nervous impulse, the chemical composition of the muscular fiber must be optimal, being especially significant the paper that plays the water, as well as the elements Calcium, Sodium and Potassium. Of there the importance of a good feeding and hydration to maintain a good health muscular. A dysfunction ligature to this chemical equilibrium is the typical cramp or incline, a momentary muscular spasm originated generally by fatigue and dehydration of the muscle. When the nerve is injured totally, the muscular contraction is literally impossible. is by their section (the nerve is broken) or by a pathology (multiple sclerosis, poliomielitis, ), the neuronal activity on a muscle does not prevent totally its function. Then the unique possible electrical activity on the muscle is the electroterapia. Used in physiotherapy with the aim of maintaining the volume and tone of the muscle, usually she is not very effective, and unfortunately muscle finishes atrophying itself and to practically disappear. Lack something, the reason of being of the muscle, the movement. So, since already you have seen other times, muscle and movement go of the hand. But, although this movement is basic the muscular function, are other functions. You want to know which are? It follows Listening Your Body kind.