《系统解剖学 Systematic Anatomy》课程教学资源（书籍教材）Part IV Nervous System-Spinal cord

PART VINERVOUSSYSTEMChapter1 General Description1.Composition of Nervous SystemII.TerminologyII.Reflexand ReflexArcsChapter 2Central Nervous SystemIN.Blood SupplyoftheBrainstemSection1 Spinal CordV.CerebellumI.Extermal Features of Spinal CordV.DiencephalonI.Intermal Structure of the Spinal CordSection3TelencephalonII.Functions of Spinal CordI.External FeaturesSection2 Brain StemII.Limbic Lobe and Limbic SystemI.ExternalAppearanceIII.Cerebral CortexIIIntemal StructureIN.Internal StructureII.ReticularFormationChapter3Neural PathwaysIV.Auditory (Acoustic)PathwaySection1 Sensory (Ascending)PathwaysV.Equilibratory PathwayI.Superficial SensoryPathwaySection2Motor(descending)PathwaysII. Deep Sensory (or the Proprioceptive) Path-I.Pyramidal SystemwaysII.Extrapyramidal SystemII.Visual Pathway and PupillaryLight ReflexChapter 4Meninges, Blood Vessels of Brain, Spinal Cord, and the Cerebrospinal FluidII. Blood Vessels of Spinal CordSectionI MeningesofBrainand SpinalCordSection3Circulationof theCerebrospinalFluidI.Dura MaterSection4 BrainBarriersII.ArachnoidI.Blood-Brain BarrierII.Pia MaterI.Blood-Cerebrospinal Fluid BarrierSection2BloodVesselsofBrainandSpinalCordII.Cerebrospinal Fluid Brain BarrierI.Arteries of BrainII. Veins of Brain· 283 ·扫描全能王创建

·284.PARTV NERVOUSSYSTEMChapter5 Peripheral Nervous SystemI.Sensory Cranial NervesSection1 Spinal NervesI.Motor Cranial NervesI.TheAnteriorBranchesof ThoracicNervesII. Mixed Cranial NervesII.The Cervical PlexusSection3Autonomic Nervous SystemII.Brachial PlexusI.Visceral Efferent (Motor) NervesIV.LumbarPlexusII.Visceral Afferent (Sensory)NervesV.Sacral PlexusIII.CentresofVisceral NervesSection2 Cranial NervesIntroductionThe nervous system controls and coordinates most of the activities of the body, matching them to thecontinuously changing circumstances of the world around.In order to carry out thesefunctions,thenervoussystemmonitors events intheexternal environmentand within the body,coordinates all this informationSkullandmatchesit againstpastexperience,and instructsBrainother systems,such as somatic muscle,to produceanappropriate response. This response will in turn alterCranial nethe information coming from thebody and the externalenvironment.Nervous system can be divided into peripheral nervous system and central nervous system (Fig.V-1).Cranial nerveXSpinal cord1.Peripheral nervous system (PNS)Spinal nervesSpinal processThis system is formed by the cranial and spinalnerves and the peripheral part of the visceral nervoussystem. It collects the information from specializedsensory receptors throughout the body and transmitsVertebral bodythis information to the central nervous system. Theperipheral nervous system also carries commands fromthe central nervous system to effectors.2. Central nervous system (CNS)The central nervous system comprises the brainand spinal cord which are wrapped in protective cover-ingsthmrlis inthecranialcaity,andthlattrlocated in the vertebral canal.Fig.VI-1 Structure of the CNS and PNS扫描全能王创建

Chapter 1 General DescriptionI.Composition of NervousSystemDendriteThe nervous system is basically formed by theSpineneroustisuewhichconsissofwoprincipalcellularCell bodyof presynaptic neuronconstituents,the nerve cells or neurons, and neurogli-Dendriteal cells or glia. The neuron is the structural and func-tional unit of the nervous system and the glia provide-AxonhillockAxonstructural and metabolic support for neurons.Myelin sheath1.NeuronsSynaptic cleftconteminal(1) Structure of neurons (Fig. VI-1-1)synapticneuroAlthough neurons are different in shapes and siz-es, each has four morphologically specialized regions(Fig.VI-1-1) : cell body, dendrites, axon, and axonFig.VI-1-1A Schematie nerve cell is shown,illusterminals. A neuron can be defined, functionally, as 3trating thedendrites, cell body, axon, and axonzones: Receptor zone(cell body and dendrites)terminalsat where the afferent or incoming impulses arrive.2)DendritesMost neurons usuallyhave many② Conducting zone(axon) specialized for conduc-dendrites.The cytoplasm of dendrites resembles thattion of the nervous impulse.Effector zone(axonof the perikaryon, with granular endoplasmic retic-terminals) where electrical or chemical signals areulum (Nissl bodies)in theirproximal trunks and attransmitted across specialized junction (synapse).points of branching. The surface area of the dendrites1) Cell body The cell body, or perikaryon isis usually far larger than that ofthe cell body.In somethe metabolic andgenetic center ofaneuron (Fig.Vneurons, the smaller branches bear large numbers of1-1,2)It contains a nucleus with a prominent nu-minutemushroom shaped projections,called dendrit-clelusfrapproriastainingroceduresoic spines, which receive the nerve impulses comingcan demonstrate within the cytoplasm of nerve cellsfrom the otherneurons (Fig.VI-1-1).neurofibrils, chromophil substance (Nissl bodies),3) Axons and axon terminalsA neuron has aGogiapparatumitcndriaattimsacntrasingle axon, which is a cylindrical tube of cytoplasmbody,andvarious incluions such as pigment,andlcovered by a membrane, the axolemma.The axonidsNeurbrilsareunquely characterisiconereconducts electrical signals from the cell body to thecellwhsamaxon terminals. In large neurons, the initial segmentobsersuellsMosseoniof axon form a coneshaped portion, the axon hillock,unsarevisualizedsmultanuslywiththeectrowhich is free of Nissl bodies.Distally each axonmicroscope.. 285 .扫描全能王创建

·286·PARTVI NERVOUSSYSTEMbreaks up into simple or extensive terminal arboriza-(2) Classification of neurons (Fig. Vtions which end as synaptic terminals (alsoknown as1-1, 4)terminal button) in contact with other cells (Fig. VI-1-1,3)to form the synapses.Collateral branches may1Based onumber of processesarisingfrom celbegiven off from the axon.byrnsaeduparruoaamioamuprons are different greatly in shape.2) Based on length of axons, neurons arealsoclasified into threetypes (Fig.V-4) GolgtypeIneurons havelong axons.The longestaxonsin the central nervous system (CNS) ofhumans ex-tend from the cerebral cortextothe caudaltipofthespinal cord adistanceof570cm; GolgitypelIneurons have short axons. The shortest axons terminateonly a few micra from the perikaryon; Amacrine neu-rons, an unusual neuron type, lack axons.Primary sensoryneuronofspinalganglion(has no trueGPrincipalneuronMotorneurondendrites)of sympatheticofspinal cordganglionFig.VI-1-2 The diaphragm of neuron cell body1 nuclear membrane;2pores in nuclear membrane;3 interior ofnucleus; 4 nucleolus; 5Golgi apparatus; 6 smooth endoplasmicreticulum; 7granular endoplasmic reticulum; 8mitochondrion; 9microtubule; 10 microfilament; 11 axon hillock; 12 initial segmentofaxon;13 soma (perikaryon)ofcell;14dendrite;15 pinocytoticvesicle; 16 lipofuscin granuleAxonDendriteAxontermialsAmacrine cell of retina(hasnoaxon)CollateralbralSA.bipolarneuronTractcell of spinalgraymatterDendriteGolgi type 1l intemeuronAxonFig. VI-1-4 Variety of neuron shapes3) Based on theirfunction, all neurons fall intoB.unipolarneuronthree types (Fig. VI-1-5). Sensory neurons receivestimuli andtransmit afferent impulsetothe CNS.Association neurons (also called interneurons) lies in theDenCollateral branchcentral nervous system forming the complex nervouscircuits.Motoneurons deliverefferent impulses fromAxonthecentralnervoussystemtotheperipheralnervousC.multipolarneuronsystem (PNS) to activate effectors.Fig.VI-1-3Morphological classification of neurons扫描全能王创建

General Description ·287.Chapter1NervecellReceptorsurfaceSynapseespecially reactivetoonekindofenvironmental changeA.a sensory neuronSynapseNervecellNervecellsB.aassociation neuronsMusclefibreMotor end plateC.amotor neuronFig.VI-1-5 Functional classification of neurons4)Based on classification of neurotransmittersstance-Neurotransmitters.Electrical synapses arechemistry,neurons may also group as monoaminer-only present in invertebrates and fishes.The chemicalgic,cholinergic,aminoacidergic,peptidergic,and sosynapses can be classified, according to the neuronalon.regions that participate informing the synapse,intoaxodendriticsynapses andaxosomatic synapses (mostSynapses and Neurotransmicommon)or,less often,dendrodendritic synapssandaxoaxonal synapses.ttersTypical chemical synapses may be divided into 3parts (Fig.VI-1-6):the presynaptic part with theCommunication between neurons usually occursdense thickening presynaptic membrane;②the post-at specialized junctions called synapses, whereexcisynapticpartwiththepostsynapticmembranethetation is transmitted from one nerve cell to another.synaptic clef,a narrowgap about 20nmwide whichWe callthe neuron sending information the presyn-separates thepresynaptic and postsynapticmembrane.aptic neuron and the other is called the postsynapticThe presynaptic part contains numerous vesicles, inneuron which receives the information.which the chemical substances neurotransmitter ispresent.(1)Synapses(2)NeurotransmittersSynapses can be formed between almost any re-gionsofthwoparticipatingnuronThmostcomNeurotransmitters are small molecular weightmontypefsyapsesoccursbetweenaterminalofancompounds;amongtheseareacetylcholine andmono-axonal branchofaneuron andadendriteorasomaofaminergic compounds such as norepinephrine andanother (Fig )hesyaes may bdivdserotonin. Amino acids (e.g.glutamate, glycine, andinowokindthhemicalsynapsesandelectrical-aminobutyric acid,or GABA)and larger molecules,synapses.The chemical synapses isthe most comsuch as peptides (e. g. enkephalin and substance P)montyeinthemammalianneroussytemwhichalso function as neurotransmitters.When an impulsetranmitsthenerousimpusebythechemicalsub扫描全能王创建

·288PART VI NERVOUS SYSTEMaresult,thepostsynapticneuronisactivatedandthimpulse is conducted from one neuron to the others.II.Reflex and Reflex ArcsMicrotubulesBasic components of reflex arcMitochondriaAreflex arc is the basic functional unit of thenervous systemTherefex archasfivebasiccompoVesiclesnents:a receptor respond to stimuli and producePresynapticnervous impulse, @ a sensory neuron transmits themembraneimpulse to the CNS, where the axons usually syn-apse with interneurons which synapse with motorPostsynapticSynaptic cleftmembraneneurons in the CNS; @ a motor neuron carry actionpotentials out of the CNS and through the PNS to Fig.VI-1-6Structures of the synapseeffector organs, such as muscles or glands, respond toarrives at thepresynaptic element, the neurotransmit-the action potentials (Fig. VI-1-7) . The response pro-terdiffuses across the synaptic cleft and bind to theduced by the reflex arc is called a reflex.receptor molecules in the postsynaptic membrane.AsDorsal rootDorsal rootganglionSensory(receptor)Peripheral nerveMotorresponse(musclefiber)Ventral rootSpinal cordFig. VI-1-7A schematic monosynaptic reflex arcis structurally the most differentiated, consisting oIII.Terminologyaxon, myelin and sheath of Schwann (Fig. VI-1-8).Myelinated fibers conduct more rapidly than un-myelinated ones. Speed of conduction is proportionalto the diameter of the fiber and the thickness of the1.Nerve fibermyelin sheath.The myelin sheath may be regarded asinsulation, whilethe extracellular space at the nodesA nerve fiber in the central nervous system con-of Ranvier and the periaxonal space provide readysists of the axon and the surrounding myelin sheathavenues for ionicdiffusion.or of the axon only in the case of unmyelinated fibers.In the peripheral nervous systembothmyelinatedand2. Nucleus and grey matterunmyelinated fibers have, in addition, an outer deli-cate nucleated membrane, the sheath of Schwann ornurilemmal sheath. The peripheral myelinated fiberAnucleus is a aggregation of neuronal cell bodies扫描全能王创建

Chapter1 General Description · 289 ·the cortex.The medullary substance or medulla is addsiarsadfcentral core of white matter beneath the cortex of theeariousinizadshmmypecerebrumand cerebellum.mmalh5.GanglionAxonfromanotherneruonIn the peripheral nervous system (PNS),the cellbodies are grouped together to form the ganglia. Sen--SynapseDendnitessory ganglion cells in dorsal roots of spinal nervesPerikaryonNissbodiesand some cranial nerves give off both central and pe-Axonhillockripheral processes, and do not have synapses on theirInitial segmentofaxoncell bodies, whilst ganglionic neurons of the visceralMyelin sheathOligodendrocytenervous system receive synaptic contacts from vari-SAxonous sources.Nodeof RanvierCENTRALNERVOUS SYSTEMPERIPHERALNERVOUSSYSTEM6.NerveSchwann cellIn the peripheral nervous system, a nerve is aCollateral branchbundle of nervefibers togetherwith supporting connective tissue.Most of nerves have a whitish appear-ance because of their myelin content Thereare threeconnective tissue sheaths in peripheral nerves.Theyare, from inside out, the endoneurium,perineuriumMotorend-platesand epineurium.Each nerve fiber is surrounded byareenforcing sheath of delicate connective tissue, theFig. V-1-8 Schematic drawing of a Nissl stainedendoneurium.It is continuous with the more abundantmotorneuronconnective tissue of the perineurium,which envelopsThe neuronal cell bodies and dendrites may formboth small and largebundles of fibers within a periph-more extensive layers or masses in the central ner-eral nerve trunk and divides the nerve into fascicles.vous system collectively called grey matter.The greyThe epineurium is the outermost sheath. This dense,matter looks grey because it consists of masses ofcollagenous layer forms an external connective tissuenerve cell bodies that contain pigment and organelles.ensheathment for all peripheral nerves (Fig. VI-1-9)Neuronal dendrites and synaptic activity are mostlyconfined to nuclei and areas of grey matter.Epineurium(aroundnerve and betweenfascicles)3. Tracts and white matterPerineurium(aroundeachBundles of nerve fibers in the central nervous sys-fascicle)tmoumraiInthbrainandspinalordconentationstrasEndoneuriumconsttutethewhitematter,socalledbecauseth(within fascicles)axons areofenensheathed inmyelin whichglistenswhite in the fresh state.Fig. VI-1-9The connective tissue sheaths in aCortex and medullary sub-4transversely sectioned nervestanceZhangjing（张长静）LiuZhiyu（刘执玉）The continuous sheet of grey matter coveringthesurfacoftherebumandrebelumialled扫描全能王创建

2CentralNervousSystemChapter 2fn tsue, slightfladdontra,Section 1Spinal Cordcated inthe uppertwothirdsofthespinalcanalofthevertebral column.Protection for the cord is providedThe spinal cord is the least modified portion ofthenot only by the vertebrae and their ligaments but alsoembryonic neural tube and the only part of the adultby the meninges and a cushion of cerebrospinal fuidnervous system in which the primitive segmental ar-(Fig. VI-2-1). The spinal cord is normally 42-45 cmrangement is clearlypreserved.long in adults with its maximum transverse diameterbeing 10-12 mm. It is continuous with the brain stemI .External Features of Spi-attheforamen magnum andterminates as theconusmedullaris at the level of the inferior border of firstnal Cordlumbar vertebra,The conus medullaris is conicalshaped.It tapers rather abruptly into a slenderfilamentThe spinal cord is an elongated, cylindrical massCerebralhemisphereCerebellumMedullaoblongatOccipital bone2nd cervical spinal ganglionSpinal ganglionDorsal roots ofthoracic spinalnervesThoracicspinalcordIntercostal nervesDorsal rootsRibs-Posterior primaryramiConus medullarisCauda equinaLumbarspinal ganglionSacral spinal ganglionlium of pelvisFig.V-2-1Spinal cord and brain of a newborn child (posterior view)·290·扫描全能王创建

Chapter 2Central Nervous System · 291 .aldlssingaralimbs, isrefected insweings orenlargements inthespinal cord,particularly in the cervical region.Theyhespnduraaerbelowsondemecervical enlargement includes segments C,-T, withmdadmost of the corresponding spinal nerves forming thebrachial plexuses for the nerve supply of the uppercyx.limbs.Segments L-S,are included in thelumbosacralenlargement, and the corresponding nerves constitutemost of the lumbosacral plexuses for the innervationof the lower limbs (Fig.VI-2-1,2)wooeom2.External longitudinal fissuresand sulciA transverse section of the spinal cord shows adeep anterior median fissure and a shallow posteriormedian sulcus,which incompletely divide the cordinto symmetric right and left halves.A shallowpos-terolateral sulcus lies a short distance lateral to theposterior median sulcus,into which a single linear ar-ray of the dorsal rootlets of spinal nerve attached.Theanterolateral sulcus marks the site of emergence ofventral rootlets.Since the ventral rootlets emerge lesstidily,often several deep rather than in a single lineararray, the anterolateral sulcus may be more difficultto distinguish. In cervical and upper thoracic spinalsegments,the posteriorintermediate sulcus indents100000the spinal cord betweenthe posterior medianand pos1000terolateral sulci (Fig.VI -2-3, 4)3.Segments of spinal cord1石The part of spinal cord associated with the emer-gence of a pair of spinal nerves is called a segmentof spinal cord (Fig. VI-2-3, 4).The spinal cord is di-vided into approximately 31 segments-8 cervical (C),12 thoracic (T),5 lumbar (L),5 sacral (S),and1coccygeal segments(Co)-thatcorrespond to 31 pairsof the dorsal and ventral roots of spinal nerves. Indi-福vidual segments vary in length; they are about twiceas long in the midthoracic region as in the cervicalFig. V-2-2 Schematic illustration of therelationships betweehthevertebralcolumn and theor upper lumbar area. There are no sharp boundariesspinal cord segmentbetween segments within the spinal cord itself.4. Vertebral levels of spinal cord1.EnlargementssegmentsmIn the third month of intra-uterine life, the spinalcireularineroseetionthelwercervicalandcord flls the length of the vertebral canal, but fromuacaeaeasothen on the vertebral column grows more rapidly thanrwsociaw扫描全能王创建

292·PARTVINERVOUSSYSTEM(Fig. V-22)The mimatch betwn levels fthethe spinal cord.Atbirth,the spinal cordextends asfarpinalodsemensabraelsioelnas the third lumbar vertebra. It reaches its adult levelmpannatinghlfeecogradually, as growth proceeds, ending at the lowerand in approaching it surgically.border level of the body of the first lumbar vertebraDenticulate ligamentFasciculus gracilisFasciculuscuneatusDorsal root ganglionDorsolateral sulcusDorsal median sulcusDorsal intermediatesulcuDorsal rootVentral rootVentralmedianfissureVentrolateral sulcusSpinal nerveFig.VI-2-3 Dorsal view of the cervical enlargement of the spinal cordPosteriorLateralgreycolumncolumnDorsal rootSpinal ganglionDorsal ramusVentral ramusVentralrootAnterior Anteriormedian greyfissurecolumnFig.VI-2-4 A stereogram of spinal cordThe approximate vertebral body levels of the spi-corresponding intervertebralforamina.Since thespi-nal cord segments are as follows (Tab. VI-2-1):nal cord is shorter than the vertebral column,the lowA dorsal and ventral root unite to form a spinalenrootgeadisaebnsnerves, which emerge from vertebral canal via theorigininthesegmentofthespinalcord andispont扫描全能王创建