·410·PARTVI NERVOUSSYSTEMInferiorganglionGlossopharyngeal n.AccessorynSternocleidomastoidAccessory n.StylopharyngeusCarotid sinus br.Vagus n.superior laryngeal n.Intermal br.TrapeziusmExtermalbr.Cricothyroid m.Brachiocephalic trunkRecurrent laryngeal n.EsophagusCardiac plexusLeft principal bronchusPulmonary trunkEsophageal plexusThoracic aortaHeartAnterior vagal trunkPosterior vagal trunkLeft lobeof liverCeliac plexusAnterior gastric br.StomachFig. VI-5-36 The vagus nerveAnterior vagal trunkPosterior vagal trunkBranchoffundusofstomachCardiac br.Hepatic br.Celiac br.Branches of posteriorAnterior gastric br.wall of stomachBranchesofanteriorwallofstomachPosterior gastric br.Crow'footCrow'footPyloric antrumFig.VI-5-37The branches of vagus nerve to stomachChenYao（陈尧）ZengZhaoming（曾昭明）the visceral functions of the body is also called theSection 3 Autonomicvisceral nervous system(Fig. VI-5-38).This systemhelps control arterial pressure,gastrointestinalmotili-Nervous Systemty and secretion, urinary bladder emptying, sweating,The portion of the nervous system that controlsbody temperature, and many other activities, some of扫描全能王创建
Chapter 5 Peripheral Nervous System · 411 :EyeballLacrimal glandNuclei of hypothalamusSalivary glandParasympatheticcentersinthebrainstemVessels of heaTracheaLungHeartLiverStomachSuprarenal glandSympathetic centers in thePancreathoracolumbarsegmentsofspinal cordKidney~12TSmall intestinLarge intestineParasympathetic centersin the sacral segments ofspinal cordUrinary bladdenAIntermal genital organDAFig.VI-5-38 Diagram showing general arrangement ofvisceral efferent nervewhich are controlled almost entirely and some onlywhich is also called the autonomic nerve is activatedpartially by the visceral nervous system. The visceralmainly by centers situated in the spinal cord, brainnervous system is dividable into the visceral afferentstem,and hypothalamus.Then the signals are trans-nerve and the visceral efferent nerve according to themitted to the visceral effectors which are the smoothmuscle, cardiac muscle and glands of the body.Oftentypeofthefibers.Thecell bodiesoftheformerarelocated in the sensory ganglia of the cranial and spinalthe autonomic nervous system also operates by meansof visceral reflexes. That is, sensory signals enteringnerve like the somatic sensory fiber, terminate in theinteroceptorofviscera.Andthevisceral efferentfiberthe autonomic ganglia, spinal cord, brain stem or扫描全能王创建
·412·PARTVINERVOUSSYSTEMhypothalamus can elicit appropriate reflex responsesThe two divisions are known as the craniosacral orbackto the visceral organs to control their activities.parasympathetic part and the thoracolumbar or sym-pathetic part. The anatomical names represent theI . Visceral Efferent(Motor)sites of origin from the central nervous system.NervesSympathetic nervous systemLike the somatic motor nerve, the visceral efferentnerve transmits the signals of the motor central to theThe sympathetic nerve originate in the spinal cordeffectors.However,ithas obviousdifferencewiththebetween the segments of T, or Cg and L(or L,) andsomatic motor nerve in the structures andfunctions:pass from here into the sympathetic chain frstly andDifferent effectors The somatic motor nerve in-then to the tissues and organs that are stimulated bynervates theskeletal muscles and it can be controlledthe sympathetic nerves. The sympathetic nervous sys-voluntarily by consciousness, whereas the visceraltem consists oftwo sympathetic trunks which is com-efferent nerve innervates the involuntary effectorscar-posed of paravertebral ganglia and interganglionicdiac muscle, smooth muscleandglands.branches,prevertebral ganlia (the celiac and superior,Different number of the neurons The visceralinferior mesenteric ganglia etc.), and nervous fibersefferentnervepathwayconsistsoftwoneuronsfromextending from theganlia to the different internal orthe lowercenterto the effector.The bodies of thefirstgans (Fig. VI-5-38, 39) .neuron, called the preganglionic neuron, lie in thecentral nervous system and terminates in a ganglion(1) Sympathetic gangliawhere they synapse with the cell bodies of the secondneuron,postganglionic neuron.In contrast, only a sin-The sympathetic ganglion include the paraverte-gle neuron exists in the somatic motor pathway.bral and prevertebral ganglia.Different fibers Different fibers consist of the1) Paravertebral gangliaThe paravertebral gangliadifferent component and diameter of the fiber.Theare arranged symmetrically on both sides of the ver-somatic motor nerve contains one kind of fibers.Buttebral column(Fig. V5-39).These ganglia are joinedthe autonomic nervous system is composed of theby interganglionic branches to form two sympatheticsympathetic and parasympathetic fibers.Each fibertrunks that extend from the base of the skull base toinnervates most of theviscera.Many organs are sup-the coccyx and are divided into cervical, thoracic,plied by both fibers,the actions of the two fibers arelumbar, sacral and coccygeal portions. There are 19-usually (but not always)antagonistic on the organ.24 ganglia in each sympathetic trunk. The cervicalBesides,the somatic motorfibers are all thick myelin-portion contains the superior cervical ganglion, theated fibers, but the visceral efferent fibers are the thinmiddle cervical ganglion and inferior cervical gan-myelinated orunmyelinated fibers.glion.There are 11 or 12 thoracic, 4 or 5 lumbar andDifferent distribution of the postganglionic3 or 4 sacral ganglia on each trunk.In the sacral por-fibers The somatic motor nerves are distributed pe-tion, the two trunks gradually approach each otherripherally in the form of nerve trunk and form theand fuse at the coccyx in the unpaired coccygealcharacteristic neuromuscular joint.Nevertheless,theganglion.postganglionicfibersofthevisceralmotornervesfab-2) Prevertebral ganglia The prevertebral gangliaricate the nerve plexuses around the viscera or bloodsituated in front of thevertebral column (Fig.VI-5-39),vessels, so the transmitters released from the termi-and are irregular ganglionic masses surrounding thenators act on several adjacent cells by the diffusionvisceral branches of the abdominal aorta they includemethods.the celiac, aorticorenal, superior and inferior mesen-The autonomic nervous system can be dividedteric ganglia.into two divisions anatomically and physiologically.扫描全能王创建
Chapter 5 Peripheral Nervous System · 413Superior cervicalganglionCervical plexuMiddle cervical ganglionInferior cervical ganglionBrachial plexusThoracic ganglia ofsympathetic trunkinterganglionicbranchIntercostal n.Greater splanchnic n.Lessersplanchnicn.Celiac ganglionAorticorenalSuperior mesentericganglionganglionInferiormesentericganglionAbdominal aorticplexusSuperior hypogastricLumbar plexuplexusSacral plexusGanglion imparFig.V-5-39The ganglia of sympathetic trunk and prevertebral gangliawith the naked eye.(2) Preganglionic, postganglionic fi-After the spinal nerve leaves the spinal cord, thebers and communicating branchespreganglionic sympathetic fibers leave the spinalnerve and pass through the white ramus into one ofThe sympathetic trunk is connected to the spinalthe ganglia of the sympathetic trunk.Then the coursenerves by communicating branches(Fig. VI-5-40) .of thefibers canbe one ofthefollowing three:It canThe communicating branches are identified as thesynapse with postganglionic neurons in the Paraverte-gray and white branches. This distinction is basedbral ganglion that it enters. ② It can pass upwards orupon thefact that the preganglionic nervous fibers aredownwards for variable distances in the sympatheticmyelinated and form the white ramus, while the post-trunk and synapse with one of the other paravertebralganglionic nervous fibers are unmyelinated and formganglia of the chain. It can pass through the sym-the gray ramus. The distinction, however, is largelypathetic trunk to terminate in one of the prevertebralacademic, since it is not possible to tell them apartganglia.扫描全能王创建
·414:PARTVINERVOUSSYSTEMSpinal ganglionSkiWhitecommunicating brSpinal n.Somatosensoryn.福Gray communicating br.Somatomotorn.Sympathetic trunkSkeletal m.Viscerosensoryn.Visceromotor n.Ganglia of sympathetictrunArrectorSweat glandPostganglionic fiberVesselsPreganglionic fibersFig. VI-5-40 Diagram of the course of sympathetic nervesThe postganglionic fibers originate from theinferior thyroid artery.The inferior cervical ganglionparavertebral or prevertebral ganglia, then travel tois situated between the transverse process of the lasttheir destinations in three ways: @Pass back from thecervical vertebra and the neck of the first rib, behindsympathetictrunkinto thecorresponding spinal nervesthe beginning of the vertebral artery.It is frequentlythrough gray rami, they control the blood vessels,fused with the first thoracic ganglion to form the cer-sweat glands, and piloerector muscles of the hairs.vicothoracic ganglion or satellite ganglion.② Surround the adjacent arteries as a layer ofThe distribution of the postganglionic fibersnervous plexus to innervate thebranches of thosearising from three cervical ganglia are described asarteries.③Terminate in a certain organ directly.thefollowings: Connecting to eight cervical nervesand accompanyingthemtothebloodvessels,sweat(3) General distributions of the sym-glands and arrectores pilorum of head and the upperpathetic nerveslimb.② Surrounding the arteries, such as the subcla-vian artery, internal carotid artery, vertebral artery,1) Cervical portion ofthe sympathetic trunk (Fig. VI-and basilar artery, form the nervous plexuses, and5-41,42)The cervical portion of the sympatheticthen accompanies the arteries to the glands, bloodtrunks consist of three ganglia according to their po-vessels,arrectorespilorumof theheadand neck,andsitions:The superior,middle,and inferior ganglia.Itthe dilator pupillae.The laryngopharyngeal brancheslies behind the carotid sheath and in front of the trans-pass to the side of the pharynx, where they join withverse process of the cervical vertebrae. The superiorbranches from the glossopharyngeal, vagus nerve tocervical ganglion is the largest of the three and placedforin the pharyngeal plexus. @ The three cervical gan-opposite the second and third cervical vertebrae.glia give off the superior,middleand inferior cardiacThe middle cervical ganglion is the smallest of thenerve respectively, which descend into the thorax tothree cervical ganglia,and is occasionally wanting.form the cardiac plexus.It is placed opposite the transverse process of sixth2) Thoracic portion(Fig. VI-5-42)Thetho-cervical vertebra, usually in front of, or close to, theracic portion of the sympathetic trunks consist of a扫描全能王创建