1.VEGETATIVE (AUTONOMIC) SYSTEMAmanda Hess Borzacchini Group 20 2nd year, 1st semester Kursk 2012

2. The vegetative nervous system controls theactivity of all organs concerned with thevegetative function of the body(respiration, fluidcirculation, reproduction, excretion, nutrition)and accomplishes trophic innervation. The trophic function of the vegetative nervoussystem is responsible for the nutrition of thetissues and organs in conformity to theirfunctioning under certain environmentalconditions (adaptational-trophic function). 3. The vegetative nervous system is separated intotwo systems: the sympathetic andparasympathetic systems. The sympathetic system is mainly concernedwith trophic functions. It is responsible fornutrient consumption, intensification of oxidationprocesses, respiration and increases the rate ofcardiac activity and supply of oxygen to themuscles. The parasympathetic system carries a protectiverole, like constriction of the pupil in brightlight, inhibition of cardiac activity, evacuation ofthe cavitary organs. 4. Comparison of the areas of distribution of thesympathetic and parasympathetic innervation discloses. Firstly some organs have the predominant role of onevegetative part over the other; e.g.: the urinary bladderreceive mostly parasympathetic innervation and thesweat glands, the spleen, suprarenals are supplied onlywith the sympathetic innervation. Secondly, in organs with double innervation, theinteraction of the sympathetic and parasympatheticnerves are antagonistic; e.g.: the stimulation ofsympathetic nerves causes dilatation of thepupil, constriction of the vessels, increase in the rate ofthe cardiac Contractions; in contrast, the stimulation ofparasympathetic nerves leads to constriction of thepupil, dilatation of the vessels, decrease in the rate ofcardiac contractions. 5. The antagonism of the sympathetic andparasympathetic system are reciprocallyaffected, the relations between them alterdynamically in the different phases of thefunctioning of this or that organ; they canact both as antagonists and as synergists. The normal function of our organism isensured by the coordination and regulationbrought by the cerebral cortex. Thesympathetic and parasympathetic aredistinguished in the vegetative systemaccording to the physiological andpharmacological data. 6. The sympathetic nervous system The central part of the sympatheticsystem is located in the lateral horns ofthe spinal cord between the level of C7and Th1-L3 in the intermediolateralnucleus. It give rise to fibres innervating thesmooth muscles of the viscera and thesensory organs (eyes), and the glands.Vasomotor, pilomotor and respirationcentres are also located here. 7. The peripheral part of the sympathetic system is formed by two symmetrical right and left sympathetic trunks stretching on either side of the spinal from the base of the skull to the coccyx where the caudal ends of both trunks meet to form a single common ganglion. 8. Each sympathetic trunk is composed of aseries of nerve ganglia of the first orderconnected by longitudinal interganglionicbranches that consist of nerve fibres. The processes of cells located in thelateral horns of the thoracolumbar part ofthe spinal cord emerge from it through theanterior roots and pass in the whitecommunicating branches to thesympathetic trunk. 9. From the white communicating branches theprocesses of the cells join by means of synapsiswith the cells of the sympathetic trunk ganglia orpass through the ganglia without interruption andreach one of intermediate ganglia. This is thepreganglionic pathway. From the ganglia of the sympathetic trunk orfrom the intermediate ganglia arise non-medullated fibres of the postganglionicpathways and pass to the blood vessels andviscera. 10. The sympathetic system has a somatic part, it isconnected with the spinal nerves providinginnervation of the soma. This connection isbrought about by the grey communicatingbranches which are segment of postganglionicfibres stretching from the sympathetic trunkganglia to a spinal nerve. As components of the grey communicatingbranches and spinal nerves the postganglionicfibres spread in the vessels, glands, and smoothmuscles of the skin of the trunk and limbs, aswell as in the striated muscles for whose nutritionand tonus they are responsible. 11. Thus, the SNS is connected with thesomatic system by two types ofcommunicating branches, white and grey. The white communicating branch(medullated) are the preganglionic fibres;they stretch from the centres of thesympathetic nervous system through theanterior roots of the ganglia of thesympathetic trunk. The centres are situated at the level of thethoracic and upper lumbar segments. 12. The grey communicating branch, thepostganglionic fibres, provide thevasomotor and trophic processes in thesoma. They connect the sympathetic trunk withthe spinal nerves for its entire length. Thecervical part of the sympathetic trunk isalso connected with the cranial nerves. All the plexuses of the somatic nervoussystem contain therefore fibres of thesympathetic system in their bundles andnerve trunks. 13. The sympathetic trunk Sympathetic trunk is ar (or abdominal) andpair formation, situatedsacral (or pelvic).at flanks of the spinalcord, consists of 20-25ganglions connectedwith interganglionicbranches. Each of the twosympathetic trunk issubdivided into fourparts:cervical, thoracic, lumba 14. The cervical part stretches from the base of the skull tothe neck of the first rib, lies behind the carotid arteries onthe deep muscles of the neck. It has three cervicalsympathetic ganglia: superior, middle and inferior. Superior cervical ganglion is the largest ganglion of thesympathetic trunk, lies on the level of the 2nd and part ofthe 3rd cervical vertebrae behind the internal carotidartery and medial to the vagus nerve. Middle cervical ganglion is small and usually located atthe intersection of the inferior thyroid artery with thecarotid artery. Inferior cervical ganglion is situated behind the initial partof the vertebral artery, it is often fused with the 1st andsometimes with the 2nd thoracic ganglion to form acommon inferior cervical ganglion. 15. The cervical ganglia send nerves to the head, neck and chest; can be divided into an ascending group passing to the head, a descending group stretching to the heart, and a group running to the organs of the neck almost immediately from the site of origin. 16. Ascending group: the nerves ofthe head arise from the superiorand inferior cervical ganglia andseparate into a group of nervesthat penetrate the cranial cavityand a group of nerves that reachthe head from outer surface. 1st group is represented by theinternal carotid nerve, from thesuperior cervical ganglion andthe vertebral branch of theinferior cervical ganglion. Both nerves form plexusesaround them, internal carotidplexus and the vertebral plexus. 17. Together with the arteries passing through thethe nerves enter the cranial cavernous sinus.cavity where theyanastomose with oneanother and send branchesto the cerebral vessels, themeninges, thehypophysis, the trunk of the3rd, 4th, 5th and 6th pairs ofcranial nerves and to thetympanic nerve. The internal carotid plexusis continuous with thecavernous plexus whichsurrounds the internalcarotid artery in the part 18. 2nd group, external, consists of salivary), and to the muscletwo branches of the superior which dilates the pupil (m.cervical ganglion, the externaldilatator pupillae).carotid nerves, which formplexuses around the externalcarotid artery and then pass inattendance to its ramifications onthe head. The plexus sends asmall ramus to the opticganglion, the facial plexus givesoff a branch accompanying thefacial artery and passing to thesubmandibular ganglion. The superior cervical plexussends fibres to the vessels(vasoconstrictors) and the glandsof the head(sweat, lacrimal, mucous and 19. Descending group: is formed by the cardiac branches of the superior, middle and inferior cervical ganglia; and together with the cardiac branches of the sympathetic thoracic ganglia and branches of the vagus nerve contribute to the formation of the cardiac plexuses. 20. The thoracic part lies in ganglia and participates infront of the neck of the ribs the formation of the cardiacand is covered by pleura. Itplexus.consists of 10 to 12ganglia. The thoracic part ischaracterized by thepresence of whitecommunicating brancheswhich connect the anteriorroots of the spinal nerveswith the sympathetic trunkganglia. The five branchesare: 1.Cardiac branch arisesfrom the superior thoracic 21. 2.Grey communicating branches are non-medullated fibres supplied to the intercostal nerves. 3.Pulmonary branches pass to the lungs to form thepulmonary plexus. 4.Aortic branches form a thoracic aorticplexus, partly on the oesophagus, oesophagealplexus, and on the thoracic duct. 22. 5.Greater and lesser splanchnic nerves: The greater splanchnic nerve originates as several rootsfrom the 5th to 9th thoracic ganglia, which pass medially tothe level of the 9th thoracic vertebra where they fuse intoone common trunk which is transmitted through thespace between the muscular bundles of thediaphragmatic crura into the abdominal cavity in whichbecomes a component of the coeliac plexus. The lesser splanchnic nerve arises from the 10th and 11ththoracic ganglia, penetrates the diaphragm together withthe greater splanchnic nerve or is separated from it by afew muscular bundles, and also becomes a componentof the coeliac plexus. 23. The lumbar (or abdominal) part consists of fourganglia. Both sympathetic trunks come closer to eachother in the lumbar part, as a result of which the ganglialie on the anterolateral surface of the lumbar vertebrae onthe medial border of the psoas major muscle. Along its entire distance the lumbar part sends off a greatnumber of branches which, together with the greater andlesser splanchnic nerves and the abdominal segments ofthe vagus nerve, form the largest unpaired coeliacplexus. The coeliac plexus lies on the anterior semicircunferenceof the abdominal aorta behind the pancreas andsurrounds the initial parts of the coeliac trunk and thesuperior mesenteric artery. 24. Coeliac trunk occupies anarea between the renalarteries, the suprarenalglands, and the aorticopening of the diaphragmand includes the pairedganglion of the coeliacartery coeliacganglion, and sometimesthe unpaired ganglion ofthe superior mesentericartery- superiormesenteric ganglion lyingunder the root of thisartery. 25. The 2nd main source ofganglion whoseinnervation of the abdominalpostganglionic fibres pass toorgans is the aorticthe pelvis as components ofplexus, formed by two trunksthe hypogastric nerves.arising from the coeliacplexus and branches runningfrom the lumbar ganglia of thesympathetic trunk. Aortic plexus gives rise to theinferior mesenteric plexus forthetransverse, descending, andsigmoid colon, and upper partof the rectum. At the origin ofthe inferior mesenteric plexuslies the inferior mesenteric 26. Aortic plexus is relation to the penis andcontinuous with themotor in relation to theunpaired hypogastric uterus and the sphincterplexus which bifurcatesurethrae muscle.at the promontory of thesacrum and is in turncontinuous with thepelvic plexus. Fibres derived from thesuperior lumbarsegments arefunctionally vasomotor(vasoconstrictor) in 27. The sacral (or pelvic) part, part usually has four ganglia. Lying on the anterior surface of the sacrum along the medial margin of the anterior sacral foramen, both trunks converge to terminate as one common unpaired ganglion impar on the anterior surface of the coccyx. The ganglia of the pelvic part are connected both by small longitudinal and transverse trunks. 28. The parasympathetic system The central part of the parasympathetic systemconsists of the cranial nerves ( III, VII, IX and X);III, VII and IX carry parasympathetic fibers tostructures within the head and neck only, whereas X(the vagus nerve) also innervates thoracic and mostabdominal viscera; and spinal (or sacral) nerves S2to S4, sacral parasympathetic fibers innervatesinferior abdominal viscera, pelvic viscera and thearteries associated with erectile tissues of theperineum. The centres give rise to the efferent fibres of theposterior horns which cause dilation of the vesselsand inhibition of contraction of the smooth musclesof the hair on the trunk and limbs. 29. The cranial part consists ciliaris)of centres lodged in themesencephalic part and inthe bulbar part (pons andmedulla oblongata). 1.Mesencephalic part isrepresented by theaccessory nucleus of theoculomotor nerve and bythe median unpairednucleus which areresponsible for theinnervation of the smoothmuscles of the eye (m.sphincter pupillae and m. 30. 2.Bulbar part isrepresented by thesuperior salivary nucleusof the facial nerve, theinferior salivary nucleusof the glossopharyngealnerve, and the dorsalnucleus of the vagusnerve. 31. The nucleus of the sacral part lie in the spinal cord, in the intermediolateral nucleus of the lateral horn at the level of the 2nd to 4th sacral segments. 32. The peripheral part ofthe cranialparasympatheticsystem consist of: 1.Preganglionic fibrespassing in theIII, VII, IX and X pairsof cranial nerves. 2.Terminal ganglia lyingclose to the organs, theciliary, sphenopalatine,submandibular, andoptic ganglia. 33. 3. Postganglionic fibreswhich either stretchindependently, e.g. theshort ciliary nervesarising from the ciliaryganglion, or pass in someother nerves, e.g.postganglionic fibresoriginating from the opticganglion and running inthe auriculotemporalnerve. 34. The peripheral part of the sacral parasympathetic system consists of fibres which run in the anterior roots of the 2nd, 3rd and 4th sacral nerves, in their anterior branches forming the sacral plexus (somatic plexus) and finally enter the true pelvis. 35. In the pelvis they leave the sacral plexus and as thepelvic splanchnic nerves pass to the pelvis plexustogether with which they innervate the pelvic organs(the rectum with the sigmoid colon, the urinarybladder, and the external and internal genitalia). Stimulation of the pelvic splanchnic nerves causescontraction of the rectum and bladder with relaxationof their sphincter muscles. The fibres of the sympathetic hypogastric plexus, incontrast, delay the evacuation of these organs; theystimulate uterine contractions, while the pelvicsplanchnic nerves inhibit it. 36. The pelvic splanchnic nerves also contain vasodilatorfibres for the cavernous bodies of the penis and clitoriswhich are responsible for the erection. The parasympathetic fibres arising from the sacralsegment of the spinal cord extend to the pelvic plexusesnot only in the erigentes and pelvic splanchnic nerves butalso in the pudental nerve (the preganglionic fibers). The pudental nerve is a complex nerve containing inaddition to somatic fibres; vegetative (sympathetic andparasympathetic) fibres that form part of the inferiorhypogastric plexus. The intramural nervous system also belongs to the PNS.(intramural system are the walls of some hollow organsthat contain nerve plexuses of small ganglia withganglionic cells and non-medullated fibres). 37. Autonomic nervous system disorder Dysautonomia (autonomic dysfunction) is a broadterm that describes any disease or malfunction of theautonomic nervous system. This includes: postural orthostatic tachycardiasyndrome (POTS), inappropriate sinus tachycardia(IST), vasovagal syncope, pure autonomicfailure, neurocardiogenic syncope (NCS), neurallymediated hypotension (NMH), orthostatichypertension, autonomic instability. And a number of lesser-known disorders such ascerebral salt-wasting syndrome. Dysautonomia isassociated with multiple system atrophy (Shy-Dragersyndrome), Ehlers-Danlos syndrome (EDS), andMarfan syndrome for reasons that are not fully