Central Nervous System · 329 ·Chapter 2Section 3 Telencepha-6. The third ventriclelonThe thidventricleisasltlikecleftwhich liesThe telencephalon (cerebrum) consists mainly ofihndhathidthe paired large cerebral hemispheres (Fig. VI -2-34),eedmainlsmthmdwhich located at the top and makes up the largest por-surcfthalmndypthalmusfomthation of the human brain. Two hemispheres are sepa-fhtidenricedathyhalmrated by a deepmedian clet, the cerebral longitudinalomiohbaofissure. The bottom of this fissure is a large bundle oftaining chorod pexs.osteroly,thethidnttransverse fibers, the corpus callosum, which crossesarowsfirlybuptlybomthemesencphalicbetween the two hemispheres. The cerebrum fills theaqueductThe thirdventriclecommunicates anteriorlysuperior area of the cranial cavity above the tentori-with the lateralventricle throughtheinterventricularum cerebelli,so the cerebrum and the cerebellum areforamen and posteriorly with the fourth ventriclecompletely separated by the cerebral transverse fis-through the mesencephalic aqueduct.sure.JiangJiying（蒋吉英）Central sulcusPostcentral gyrusPrecentral gyrusPostcentral sulcusPrecentral sulcusSupramarginal gyrusMiddlefrontal gyrusIntraparietal sulcusSuperior frontal gyrusAngulargyrusParietooccipital sulcusOccipital poleCerebral transversefissureFrontal poleCerebellumInferiorfrontal gyrusTemporal poleInferior temporal sulcusLateral sulcusInferiortemporal gyrusSuperior temporal sulcusMiddleSuperior temporal gyrusMedulla oblongatatemporalgyrusFig. V-2-34 The superolateral surface of cerebral hemisphere扫描全能王创建
·330·PARTVI NERVOUSSYSTEMEach cerebral hemisphere is composed of anborder;medial border, including the medial occipexternal stratum of grey matter, termed the cerebralital and medialorbital border,between the tentorialcortex, and an underlying internal white matter, theregion and the medial surfaceinposteriorpar,themedullary substance. Within the hemisphere, there areorbital regionfrom themedial surfacein anteriorpart.several gray matter masses deeply situated, knownThe surface of the cerebral hemispheres becomesas the basal nuclei (ganglia), and a cavity, called thethecomplicatedfodings, that is, elevations (upfolds)lateral ventricle.called gyri and depressions (downfolds) refered toThe cerebral cortex is particularly well developedas sulci or fssures, which increases the surface areain human and is responsible for many higher brainto about three times. The area of the human cortexfunctions, including manual dexterity (for example,is about 2200 cm', one third of this being visible onthe “opposing thumb" and playing the piano etc.),the surface while two thirds is obscured in the sulcidiscriminative aspects of sensation,and cognitiveand fissures.Although most gyri are constant, othersactivity, such as language, reasoning, learning andvary in their dimensions and minor details, not onlymemory etc.in different individual but in the hemispheres of samebrain.There are four constant sulci (or fissures) for lobeI.External Featuresdemarcation on the surface of the hemisphere. Thelateral sulcus begins as a deep furrow on the inferiorEach side of the cerebral hemisphere presentssurface of the hemisphere, runs posteriorly and up-three surfaces or aspects: superolateral (dorsolateral)wards onto the dorsolateral surface.The central sulcus,medial and inferior surfaces (Fig. VI-2-34, 35).Thestarts in the superior border of the hemisphere aboutsuperolateral surface is convex adapted to the cranial1 cmbehind themidpointbetween thefrontal andcavity.The medial surface is flat and vertical.Theoccipital poles,it then slopesdownward andforwardinferior(basal)surface is irregular anddivided intostopping just short of the lateral sulcus.Its superiororbital (anterior)and tentorial (posterior)regions.Theend extend to themedial surface of thehemisphereanterior and posterior hemispheric extremity is calledThe circular sulcus (circum insular fissure) lies deepthe frontal pole and the occipital pole respectively.within the lateral sulcus and surrounds the insula.TheAbout 4 cm anterior to the occipital pole on the in-parieto-occipital sulcus starts in the calcarine sulcus,ferolateral border is the preoccipital incisure (notch).then runs upward to turn to the dorsolateral surface;The surfaces are separated by three borders: su-it lies in the posteriorportion on themedial surface,peromedial (superior)border,between the supero-starting in the calcarine sulcus upwards to the dorso-lateral and medial surfaces;@ inferolateral border,lateral surface, and separates the parietal and occipitalbetween the superolateral and basal surfaces (its ante-lobes as its name indicates (Fig. VI-2-35)rior part separates the superolateral surface from theorbital surface in the frontal lobe, as the superciliaryCentral sulcusof insulaCircular sulcus of insulaShortgyriof insulaLong gyrusof insulaFig. VI-2-35Theinsula扫描全能王创建
Chapter 2 Central Nervous System · 331 ·The hemisphereconsists ofsixlobes oneachsideinto superior, middle and inferior temporal gyri. TheThe superolateralsurfacofthe hemispherecanbemiddle part of the superior temporal gyrus forms twodividdinfvlbes (includinganinsula)bythesor several short gyri in the floor of the lateral sulcus,sulci and an imaginary line joining the upperendofknown as transverse temporal gyri.hpariecpitaluluhpecipianIn the occipital lobe, the calcarine sulcus beginsvzimagnaryparietoccipial lineThfrontallobeon the medial surface of the hemisphere near the oc-istheareainfront ofthecentralsulcus and abovethecipital pore and extends forward to an area slightlylateralsulcus.Theparietallobeistheareaboundedbelow the splenium ofthe corpus callosum.The otherbynralsuuaeralsuuadthmsulci and gyri of this lobe are not constant.inary line.The area posterior tothe imaginary lineandtheparietoccipitalsulcusisoccipitallobewith2. Sulci and gyri on the medial andpyramidshapewhichlies intheposerior portionofinferior surfaces of the hemisthe hemisphere.The temporal lobe occupies the areainferior to the lateral sulcus and in front of the imag-phereinary line. The insula (insular lobe) (Fig. VI-2-35),being triangular shaped island, lies deeply in the floorOn the medial surface, the cingulate gyrus isof the lateral sulcus, and is overlapped by portionsseparatedfromthecorpus callosumbythecallosalof the frontal, parietal and temporal lobes. It can besulcus (Fig.VI-2-36).The cingulate sulcus intervenesexposed by separating the upper andlowerlips ofthebetween the cingulategyrus and the extension of thelateral fissure,bounded by the circular sulcus.Anoth-superior frontal gyrus on the medial surface of theer lobe, called the limbic lobe, is the circular area inhemisphere.After it gives off the paracentral sulcus,the medial surface of the hemisphere, which mainlyitbranches intothemarginal sulcus (ramus)and sub-surrounds the corpus callosum.parietal sulcus. The region bounded by the paracentraland marginal sulci is paracentral lobule. It is around1. Sulci and gyri on the superolathe end of the central sulcus, and formed by the pre-central and postcentral gyri which extend from theteral surface of the hemispheresuperotaleral surface onto the medial surface of thehemisphere (ie.the continuation of the precentral andIn dorsolateral surface of the frontal lobe, the pre-postcentral gyri).The parieto-occipital sulcus andcentral sulcus (often considered as two ormore parts)calcarine sulcus are two obvious sulci on the posterioris in front of and parallel to the central sulcus, thesepart of the medial surface. The former is describedsulci demarcate the precentral gyrus (Fig. VI-2-34) .previously. The calcarine sulcus continues for a shortThe superior and inferior frontal sulci extend forwarddistance over the occipital pole and joins the parieto-and downward from the precentral sulcus, dividingoccipital sulcus in a Y-shaped formation. The wedgethe remaining surface of the frontal lobe into threeshaped gyrus between these sulci is termed the cuneparallel gyri:superior,middleand inferiorfrontal gyrius.The cortex on the banks of the calcarine sulcus is(Fig. VI-2-34) .termed the striate area (visual cortex).In the parietal lobe, the postcentral sulcus liesOn the inferior surfaceof thehemisphere(Fig.VIbehind and paralleltothe centralsulcus, thesesulci2-37)agyrus extends fromtheoccipital polealmostbound the postcentral gyrus.The intraparietal (orto the temporal pole.The posterior part of this gyrusinterparietal)sulcus extends posteriorlyfrom theconsists of the lingual gyrus,the anterior part formsmieftheoentralsulcus,anddividestheparthe parahippocampal gyrus which hooks sharplybehindthe postcentralgyrus intosuperiorand inferiorbackward as theuncus.arialbulesTheortionsotheinferoarietaOn the orbital surface of the frontal lobe,the ol-lobulethat surroundtheupturnedendsofthelateralfactory bulb and olfactory tract conceal most of thesulcusandthesuperiortemporalsulcusarecalledtheolfactory sulcus.The former receives the fibers of thesupramarginalgyrusand theangulargyrusrespecolfactorynerve; the latter extends to form the olfacto-tively.ry triangle. The gyrus rectus is medial to the olfactoryIn the temporal lobe, the superior and inferiorsulcus, and the large area lateral to the olfactory sul-morasungowadallthlracus consists of irregular orbital gyri (Fig. VI-2-37).udivdralsumra扫描全能王创建
·332·PARTVINERVOUSSYSTEMTrunk of corpus callosumParacentral sulcusCentral sulcusFornixParacentral lobuleCingulate sulcusSpleniumofcorpus callosumCingulate gyrusMarginal ramusGenu of corpus callosumParietooccipital sulcusSuperior frontal gyrusCuneusRostrumofcorpuscallosumFrontalpole-Calcarine sulcusLingual gyrusSubcallosal gyruParaolfactory areaOccipital poleDentategyrusLateral occipitotem-Temporal poleporalgyrusOccipitotemporalsulcusUncusCollateral sulcusParahippocampal gyrus Medial occipitotemporal gyrusFig.VI-2-36 The medial surface of cerebral hemisphereFrontal poleOrbital gyrusOlfactorybultOlfactory sulcusOlfactory tractOlfactory trigoneAnteriorperforatedsubstanceOpticchiasmaTubercinereumUncTubercinereumMamillary bodyParahippocampal gyrusHippocampal sulcusMedial occipitotemporal gyrusCollateral sulcusOccipitotemporalsulcusLingual gyrusLateral occipitotemporal gyrucipital poleFig.V-2-37 The inferior surface of cerebrum扫描全能王创建
Chapter2 Central Nervous System · 333 .The hippocampal formation'consists of thedentegyrus,thehippoampusproper alsocalledII . Limbic Lobe and Limbichippocampus, or Ammons horn),the subicular com-Systemplex and the entorhinal cortex (Fig. VI-2-37, 38, 39).It is situated closer to the diencephalons folded androlled inward so that it is submerged deep below theLimbic lobeparahippocampal gyrus.Hippocampus, like an arcu-ate eminence, lies in the foor of the lateral ventricle.Dentate gyrus is a narrow, scalloped strip of cerebralOnthe medial surfaceof the cerebralhemispheregyrus between the hippocampus and parahippocampalseverarelated areashecerebralcorexfomecorticalcomplexlimbus (brder)betwenthegyrus.Amygdaloid body (amygdala) is a gray matterdiencephalon and the more lateral neocortex of themass composed of several groups of neurons that arecerebral hemispheres,socalledthelimbic lobeThislocatedatthetail endofthecaudatenucleus,betweenlimbic lobeconsists primarilyofaring ofcortexoutthe uncus and the parahippocampal gyrus. Septal nu-side the corpus callosum, mainly made up of the cin-clei are located within the septal area which is formedgulat,parahippocampal gyri,uncus,the hippocampalby the regions under the corpus callosum (subcallosalformation and septal area and extending from thegyrus or paraolfactory gyrus) and paraterminal gyrus.posteriorofthe corpus callosum to themedial surfaceMamillarybodies of thehypothalamus aretworoundof the temporal lobe as well as the lateral ventriclemasses close to the midline near the cerebral pedun-(Fig, V -2-38).cles. Anterior nucleus of the thalamus is located inthe floor of the lateral ventricle. Olfactory bulbs areLimbic systemflattened bodies formed by the olfactory nerves andneurons, lying in the olfactory sulcus on the orbitalIt is used to include the limbic lobe as well assurface of the frontal lobe.The entorihinal cortex isassociated subcortical structures, including the cingu-located in the parahippocampus.Bundles of connect-late gyrus, hippocampal formation, amygdaloid body,ing myelinated axons interconnect various compo-septal nuclei, hypothalamus (especially mamillarynents of the limbic system,which include the fornix,body)，anterior nucleus ofthalamus,olfactorybulbstria terminalis, stria medullaris, medial forebrainbundleandmammillothalamictract.and tegment of the midbrain (Fig. VI-2-38)Anteriornucleus ofthalamusIndusium griseum and longitudinal striaeStria medullarisMammillothalamictractFomixCingulate gyrusCorpus callosum.Stria terminalisAnteriorcommissureSeptal nucleiHippocampusMammillary bodyOfactorybulbTegmentAmygdaloid bodyDentate gyrusParahippocampalgyrusSeeedcmponensofthelimbiystemandsurounding strucurFig.VI-2-38扫描全能王创建
·334·PARTVINERVOUSSYSTEMPes hippocampiInferior hom of lateral ventricleUncusHippocampusPahippocampal gyrusDentate gyrusFimbriaCollateraleminenceSplenium-CollateraltrigoneForceps majBulb of posterior comiCalcar aviPosteriorcormuA.hippocampus,the posterior inferior horn of the rightlateral ventricle(posted from above)HippocampusFimbriaAlveusFimbriodentatesulcusPolymorphic layer-Pyramidal layerDentategyrus-Molecular layerProsubiculumInferior horn of lateral ventricleSubiculum-Presubiculum/ParasubiculumEntorhinal areaB.hippocmpus andrelated struture(seen in a coronal sectionofthefloorofthe inferiorhomofthelateral ventricle)Fig.VI-2-39 Hippocampus and hippocampal formationIn the limbic system,hippocapal efferent fibersThe limbic system participates in the organizationtravel in the fomix and synapse neurons in the ma-of the autonomic nervous system. Most of the limbicmillary bodies.These neurons of the mamillary bodysystem output connects to hypothalamus, in part viaproject axons to the anterior thalamic nuclei via thethe medial forebrain bundle. Stimulation of variousmamillothalamic tract.The anterior thalamic nucleilimbic system can produces changes in cardiovascularproject, in turn, to the cingulate gyrus, which containsor gastrointestinal functions. However, the sympathet-the cingulum that reaches the parahippocampal gyrus.ic and parasympathetic aspects of autonomic controlSo, the circuit is formed: parahippocampal gyrusare not well localized in the limbic system.hippocampal formation -mamillary bodies-→anteri-The limbic system, especially the hippocampusor thalamic nuclei -cingulate gyrusparahippocam-together with the mamillary body and the portionspal gyrus. This circuit ties together the cerebral cortexof the cerebrum, functions in memory and learningand hypothalamus, called the hippocampal circuit orExperimental and clinical observations suggest thatPapez circuit after the neuroanatomist who defined it.memory impairment results from lesions in the limbicIt provides an anatomic substrate for the convergencesystem. People with the hippocampus and adjacentofcognitive (cortical learning and memory)activities,cortex in the medial temporal lobes damage may for-emotional experience, and expression.get recent events and even cannot commit anything to扫描全能王创建
Chapter 2 Central Nervous System · 335 .tiaa40% of the weight of the human brain. Phylogenet-atailyutwmically,the cerebral cortex is often divided into twotemfunctionsinmemoryremains uncleartypes: an older (original) part, consisting of the ar-Thelimbicsystemalsofunctionsinthemotionalchicortex (including hippocampus and dentate gyrus)aspcsobhavilatdsurivalEermenand paleocortex (mesocortex), such as entorhinalonthelimbicsystemofmonkeysandotheranimalscortex,and a newer development,neocortex.Thecorindicatethatheamygdaloidnucleusassumesamajortex has a characteristic structure, consisting of nerveroleincontrolling theoverall patternofbehaviorcells (neurons) and nerve fibers arranged in layers.Amygdaloid body reives thefibers from hypothal.Generally,the ncocertex can be divided into six layersamusandassociationareasinthfronta,temporal(Fig.VI-2-40),from the most external surface to theinulaandfactryortexonrunbackfrmdeep layer in proper order: the molecular (plexi-amydaloidbodyothassociationortexpreopform),contains nonspccific afferentfibers that comearea and hypothalamus.The amygdaloid body mod.from inner parts ofthe cortexorfromthethalamusulates sensory information processing in the associ-@external granular, is a rather dense layer composedation cortex, and also participates in regulating enofsmallcells(neurons);③externalpyramidal,condocrine activity, sexual behavior, and food and watertains pyramidal cells,frequently in row formation,intake. Lesions in some areas of the amygdaloid bodywhich send association fibers to other cortical aeras:can modify, inhibit, or unleash these behaviors.@ internal granular, is usually a thin layer with cellssimilar to those in external granular layer. These cellsOtherexperiments haveshownthat the limbicareinterneuronswhich receive specificfibersfromsystem is associated with pleasure and pain. Whenthe thalamus and remain its output fibers within thecertain areas of the limbic system or the thalamus, hyinternal pyramidal,containspyramidialpothalamus, and midbrain are stimulated in animals,cortex;cells that are fewer in number but larger in size thantheir reactions indicate that they are experiencingthose in the external pyramidal layer. These cellsintense punishment.When other areas are stimulated,project axons to distal structures (eg., brain stem andthe animal reactions indicate that they are experienc-spinal cord);polymorphic (multiformorfusiform)ing extreme pleasure.Electrical stimulation of thelamina,consists ofirregularfusiformcellsgivingriseamygdaloid nucleus in humans may result in fear,to corticothalamic projections. The details of theseanxiety,or rage and aggression.Because it assumes alayers differ from one region to another.From neocor-primary function in emotions such as pain,pleasure,tex to archicortex, they change their structure from arage,fear, sorrow,sexual feelings,docility and affec-modified six layered to a four or three layered cortex,tion, the limbic system is sometimes called the “vis-for instance, the hippocampus is a primitive trilami-ceral brain" or"emotional brain"nar cortex with molecular, pyramidal, and polymor-The limbic system is concerned with: cogni-phic layers from the original external surface to thetive processes involved in memory:② controling theventricular ependyma,whereas thetransition eventsvisceral and endocrine activity; emotional expres-from hippocampus to parahippocampal gyrus changesion and genesis, together with visceral response totheir structure to four layers,five layers and six layersthe emotions, survival of individual and species.The(including prosubiculum, subiculum, presubiculum,limbic system is also known as the visceral brain be-parasubiculum)(Figs.VI-2-41)cause ofits substantial influence on visceral functionsThe cerebral cortex has been divided into cytoar-through the autonomic nervous system.chitectural areas, based on differences in the thick-ness of individual layers,neuronal morphologyin theII . Cerebral Cortexlayers, and connection of nervefiberlamination.Themost commonly employed system is the Brodmann'ssystem, Brodmann's map, which consists of approx-Histological structure of theimately 52 areas (Fig. VI-2-40). These anatomicallydefined areas have been used as a reference base forcerebral cortexthe physiologic and pathologic processes.Each cerebral hemisphere has a mantle of grey扫描全能王创建
·336·PARTVINERVOUSSYSTEMelicited by electrical stimulation.The remainder ofthe2.Functional localization of theneocortex falls under the general heading of associa-tion cortex,whichmaybecloselyrelated functionallycerebral cortexwith the sensory areas or have an essential bearing oneven more complex levels of behaviour and the intel-Clinicopathologic studies and animal experiments,lect.including ablation, stimulation and more recentlyIt is convenientto consider the neocortex as con-functional brain imaging,haveprovided informationsisting ofthefollowingtwomainparts:cortexoftheconcerning functional localizations and particularparietal and temporal lobes, and cortex of the frontalcortical areas in different regions of the cerebral cor-lobe. The former is concerned with the receptiontex (Figs. VI-2-42).Three main sensory areas are forand conceptual elaboration of sensory data, where-general sensation (somatosensory),vision and hear-as the latter is concerned with motor responses anding, to which may be added gustatory and vestibularjudgements, foresight, and moods associated withareas.Thereare alsomotorareas(somatomotor)frombehaviour.which contraction of the skeletal musculature can beFig.VI-2-40Thesubdivision of the cerebral cortex扫描全能王创建
Chapter 2 Central Nervous System · 337 H张KRepresentation ofthe layers of the human cerebral cortexFig.V-2-41It consists ofareas3,1 and2 inBrodmann'smap.Itis possible to elicit motor responses by stimulating(1) Primary somesthetic area (gener-the somesthetic area,as well as sensoryresponsesal sensory area or somatosensoryfrom the motor area in the precentral gyrus.The con-area)nections and functions of the two areas, therefore,overlapto someextent and they shouldbe consideredIt occupies the postcentral gyrus on the supero-asa sensorimotor strip surrounding the central sulcuslateral surface of the hemisphere and the posterior(Fig.VI-2-42)part of the paracental lobule on the medial surface.Premotor areaMotorarea(Primarymotorarea)Somesthetic area(General sensory area)Writing areaVisual language area(Sensorylanguagearea)Synergetic motorareaofeyeballMotor speech area(Broca's area)VisualareaAuditory languageareaAuditoryarea(Auditory speech area)扫描全能王创建
·338·PARTVINERVOUSSYSTEMMotorareaSomestheticareaVisceralregulatingcenterVisualareaOlfactoryareaFig. V-2-42 The main functional areas (centers) of the cerebral cortexThe general sensory area receives somatosen-(2) Primary motor area (motor area orsory input from theventral posterior nucleus of thesomatomotorarea)thalamus. The fibers traverse the internal capsule,conveying data for the various modalities of generalIt is located in the precentral gyrus, including thesensation,which includes pain,thermal,touch (alsoanterior wall of the central sulcus and the anterior parttactile)pressure,position,movementandvibratoryof theparacentral lobule onthemedial surface of thesense. Each point of the somesthetic area receiveshemisphere, corresponding to area 4 of Brodmann.sensations from specific parts of the body,which isThe motor cortex, in which giant pyramidal cellsthe sensory area organized somatotopically.The con-(Betz's cells) is present in the fifth layer.tralateral half of the body is represented as inverted.The main sources of input to area 4 are the pre-(Fig.VI-2-43).The pharyngeal region, tongue, andmotor cortex (area 6),the somesthetic cortex, and thejaws are represented in the most ventral (lowest) partventral lateral and ventral anterior thalamic nuclei.of the somesthetic area, followed by theface,hand,The efferents fibers form the pyramidal system (cor-arm, trunk, and thigh. The area for the remainder ofticonuclear and corticospinal tracts) to terminate thethe leg and the perineum is in the extension of themotor nuclei of the brain stem and the anterior hornsomesthetic cortex on the posterior part of the func-of the spinal cord. About 40% of these fibers arise intional importanceof the part and its needfor sensitiv-area 4, the remains originate in area 6 of the frontality.Thus the areafor the face, especially the lips, islobe and in the parietal lobe, including the somesthet-disproportionatelylarge, and a large area is signed toic area.the hand, particularly the thumb and index fingers.Electrical stimulation of the motor area elicitsIn addition to the main or primary somestheticcontraction of muscles predominantly on the oppositearea already discussed, the existence of a secondaryside of the body. Although cortical control of the skel-somesthetic area has been demonstrated in primates,etal muscle is mainly contralateral, there is significantincluding man. This small area is situated in the upperipsilateral controlofmost ofthe muscles of the axialbank of the lateral sulcus posterior to the central sul-body including head. The body represented in thecus and extends to the insula. The parts of the bodymotor area is inverted, the pattern being similar toare represented bilaterally,although contralateral repthat described in the somesthetic cortex (Fig. VI -resentation is predominated (Fig.VI-2-42)2-44). The sequence is pharynx, larynx, lips, tongue扫描全能王创建