The muscle belly is located on the central part of the muscle between his origin and insertion tendons. It is red, highly variable in length and volume (contraction/relaxation) and with large number of blood vessels. A muscle is composed of what is formed by the union of thousands to millions (depending on the muscle) of your basic cellular units, muscle fibers. They unite both lengthwise and crosswise, forming small groups of fibers called fascicles or you do muscle, at the same time also de-interleaved side by side to form the muscle itself. The fact of separating fibers in different fascicles is a preventive approach with regard to possible injury. If the muscle is formed by an only fascicle, in case of breakage would be totally disabled to perform their motor function. We can say that the muscle fiber is divided into still smaller functional structures, the mofibrillas. We will not go into detail, since we desviariamos us of our goal.
How a muscle contracts another actor, the nerve. A muscle contracts thanks to an electrical stimulus, a nerve impulse. The order of shrinkage comes from the central nervous system, consisting of the brain and spinal cord. This stimulus occurs on a voluntary basis, when we want to generate a movement, or involuntarily as a consequence of a reflection (usually defensive), but sometimes also due to malfunctioning nerve, causing what we call Contracture (involuntary contraction sustained over time). This anomaly can come from two sources. One physiological, in which the nerve has been irritated, injured, or compressed by any other structure of the body (a joint, muscle, inflammation).
Another emotional, as a way to escape from a nervous excessive activity, generating stimulation of contraction to various muscles of the body, usually close to the central nervous system (head, neck and back). The chemical balance of your cells is also transcendental in the contraction of the muscle. Both for contraction itself as for the transmission of the nervous impulse, the chemical composition of the muscle fiber has to be optimum, being especially significant the role played by water, as well as the elements calcium, sodium and potassium. Hence the importance of good nutrition and hydration to maintain good muscle health. A dysfunction linked to this chemical equilibrium is typical cramp or ramp, a momentary muscle spasm usually caused by fatigue and dehydration of the muscle. When the nerve is totally injured, muscle contraction is literally impossible. By its section (nerve has been broken) or by a disease (multiple sclerosis, poliomyelitis,), not neural activity over a muscle completely prevents its function. Then the only possible electrical activity on muscle is electrotherapy. Used in physiotherapy with the objective of maintaining the volume and tone of the muscle, usually not very effective, and unfortunately the muscle just by atrophy and virtually disappear. Missing something, the raison d ‘ etre of the muscle, movement. So, as you’ve already seen sometimes, muscle and movement go hand in hand. But, although that movement is the basic muscular function, there are other functions. Do you want to know what? He remains attentive to listen to your body.