Peripheral nervous system
The peripheral nervous system, or in abbreviated form PNS, is system which connects extremities and bodies to the central nervous system. Neurons of this nervous system are abroad TsNS – back and a brain.
Unlike TsNS, the peripheral nervous system does not possess protection in the form of a blood-brain barrier or bones therefore it can be damaged mechanically or as a result of influence of toxins.
The peripheral nervous system is subdivided into a vegetative nervous system and somatic, at the same time in some sources it is possible to meet references of a touch nervous system.
The somatic peripheral nervous system is responsible for receiving incentives from external environment, and also for coordination of movements of a body. It regulates activity which is in full understanding.
The vegetative nervous system is classified on enteral, parasympathetic and sympathetic. The role of the first look consists in management of work of a rectum, small intestine, stomach, gullet, that is all aspects of the alimentary system. The parasympathetic nervous system becomes active when the person feels is weakened or has a rest, it in the answer for stimulation of work of urinogenital system, expansion of blood vessels, heartbeat delay, narrowing of pupils, digestion work normalization. The leading role of a sympathetic nervous system consists in reaction to a stress or potential danger, together with other physiological changes this system promotes increase of level of adrenaline at nervousness, to increase in a blood pressure and pulse rate.
Thus, it is possible to carry 12 pairs of nerves to a peripheral nervous system, their vegetative and sensitive a ganglion, the roots located on the course of these nerves and also 31 pairs of spinal nerves, back and ventral roots of a spinal cord and many other nervous educations.
As PNS connects back and a brain with receptors and muscles, the sensitive and motive impulse has to reach the central nervous system very quickly. Though motor reactions of an organism also seem instant on various irritants, during this time the signal has to run a long way from receptors to TsNS and in the opposite direction. Scientists counted that the speed of such signal reaches more than 90 meters per second. But such superspeeds are necessary not for all functions of an organism.
Defeats of a peripheral nervous system, as a rule, are acquired. Usually they are connected with infections, injuries, intoxications, vascular and metabolic disorders, a vitamin deficiency, and also some other scarce states. However and hereditary diseases take place, among them there is neural amyotrophy, hypertrophic a polynephropathy. Neuritis, plexites, radiculitises, ganglionites also belong to diseases of a peripheral nervous system. Plexites usually arise because of a prelum of trunks of various textures muscles, pathological changed; the active virus of herpes quite often leads to defeats spinal a ganglion, etc.
Damages of spinal roots at the time of delivery, trunks of a brachial plexus are the frequent reason of various pathologies of a peripheral nervous system at children's age.
Malignant and benign tumors of a peripheral nervous system meet rather seldom, however their emergence at various levels of system is possible.
Clinical inspection of the patient is the cornerstone of diagnosis of defeats of a peripheral nervous system. In a zone of defeats paresis and paralyzes, sensitivity disturbance, trophic and vegetovascular frustration in a zone disturbance of functionality of a nervous trunk, as a rule, meet. Carry out such methods of research as electrodiagnosis, an electromyography, a hronaksiodiagnostika, heatinvasive research, a computer tomography, histochemical and histologic researches. The choice of a technique of research in many respects depends on the place of localization of disturbance of functionality of elements of a peripheral nervous system.
Treatment of diseases of a peripheral nervous system is connected with elimination of an etiological factor, improvement of exchange and trophic and microcirculating processes in a nervous system. Register vitamins of group B, anabolic hormones and drugs of potassium, niacin drugs, stimulators of nerve conduction, also appoint physioprocedures, sanatorium treatment, physiotherapy exercises, massage.
