Chapter 4 Meninges, Blood Vessels ofBrain, Spinal Cord, and the CerebrospinalFluidintervertebral foramina.Section 1Meninges ofThe epidural space and its contents protect thespinal cord from injury. The lymphatic vessels andBrain and Spinal Cordvenous plexus in the vertebral canal all drain into thevessels or plexus of the thoracic and abdominal cavi-The brain and spinal cord are enclosed by threeties.The alterations of the pressure in the thoracic andlayers ofmembranesofconnectivetissuetheme-abdominal cavities can cause changes in the volumeninges: the dura mater is an outer tough and denseof the vertebral canal and the pressure of the cerebro-protective membrane,② the arachnoid is an interme-spinal fluid.diate spiderweb-likedelicate membrane,and ③thepia mater, is an innermost thin translucent, delicateand fibrous membrane,which is rich inblood vesselsCerebral dura materand is adherent to the surface of the brain and spinalcord.Thesemembranes are continuous at the foramenThe cerebral dura mater lines the interior of themagnum.skull, and serves the twofold purpose of an internalperiosteum to the bones, and it protects the brain fromI.Dura Materinjury.It is composed of two layers,an inner or meningeal and an outer or periosteal, closely connectedtogether, except where they separate to enclose theblood-filled dural sinuses(Fig.VI-4-2),endosteum Spinal dura materThe cerebral dura mater is in loose contact with thecalvaria, so that epidural hematoma often happen inThe spinal dura mater (Fig. VI-4-1) forms a loosethis area; where, the cerebral dura is closely attachedsheath around the spinal cord. There is a space be-to the base of skull, and cerebrospinal fluid may leaktween the dura and the periosteum of the vertebralout from the nose or ear with a fracture of the base ofcanal,which is called the epidural space.The epiduralskull, because of accompanying laceration of the ce-space contains a quantity ofloose areolar tissue, lymrebral dura mater and arachnoid.phatic vessels and venous plexuses. The spinal nervesThe cerebral dura mater sends inward four pro-on each side pass through theepidural space which iscesses which divide the cavity of the skull into aapplicableforblockanesthesia.series offreely communicating partitions, which limitThe dura mater of the spinal cord is continuousmovement of the brain within the cranium, includewith the dura of the brain, and is attached tothe cir-thefollowings:cumference of the foramen magnum, so that the epi-1) The cerebral falx, so named from its sickledural space is not open into the cranial cavity.like form, is a strong, arched process which descendsThe dural sac becomes thinner at the level of thevertically in the longitudinal fissure between the ce-second sacral vertebra, and closely invests (thefi-rebral hemispheres. It is attaching to the crista gallilum terminale to attach at the back of the coccyxofthe ethmoid bone anteriorly and to thefree inferior(Fig. V-2-5) .Lateraly, the spinal dura is continuousmargin just above the corpus callosum.with the external membraneofthe spinal nerveat the·361.扫描全能王创建
·362·PARTVINERVOUSSYSTEMLigament flavaArachnoid materEpidaural spaceSpinal daramaterSubarachnoid spaceSpinal pia materDonticulate ligPosteriorrootAnterior rootAnteriorbranchVertebralVertebral a.Posterior longitadial ligFig. VI-4-1 The coverings of the spinal cordInferiorsagittalsinusGreater cerebral v.riorpetrosalsinusS1Transverse sinuInferiorpetrosalsinusInternal carotid aStraight sinOpitcnConfluence of sinusHypophysisCavernous sinusCerebellar tentoriSuperiorophthalmicySuperior petrosal sinuPterygoid venous plexusTrarMastoid emissarySigmoid sinusFig. VI-4-2 The cerebral dura mater and the sinuses of dura mater2) The cerebellar tentorium, is a horizontallygyrus and uncus are located just above the tentoriallocated arched lamina, elevated in the middle, andincisure, increased intracranial pressure can move theinclining downward toward the circumference. Itthe parahippocampal gyrus and uncus downwards tocovers the superior surface of the cerebellum,andform the tentorial hernia. With the enlargement of thesupports the occipital lobes of the brain. Its anterioripsilateral pupil, paralyses of the homolateral extermalborder is free and concave, and bounds a large ovalocular muscles and contralateral hemiplegia will oc-opening,the tentorial incisure,for thetransmission ofcur because the hernia presses the oculomotor nerverthe cerebral peduncles.Because the parahippocampaland cerebral peduncle.扫描全能王创建
dhn3) The falxcerebellisasmall midinetriangularcavemous sinus is located on each side of the sellaposturcica(Fig. VI -4-3).The intermal carotid artery andaabducent nerve runs through the cavernous sinus andand back partofthetentorium.the oculomotor, trochlear nerves, and the ophthahmic4)The diaphragma sellaeisasmallcircular hori-and maxillary divisions of the trigeminal nerve passzonafdwhchroofssearandmthrough its lateral wall into the orbit. Because thecompletely covers the hypophysis; asmallcentralsuperior(and inferior)ophthalmic vein drains intotheopening transmits the infundibulum.cavernous sinus,facial infection can spread to theAt certain sites two layers of the cerebral duracavernous sinus resulting in sepsis and thrombosis ofmaeris separated and form large venous sinusesthe venous sinuses,and even involve the adjacent cra-called the sinuses of dura mater dural sinuses), intonial nerves.The superior and inferiorpetrosal sinuseswhich the cerebral veins are drained.Ahemorhagedrain the blood from cavernous sinuses into the trans-caused by an injury ofthe dural sinuses is dificulttoverse sinuses and the internal juglar veins respec-stop because the wall of the dural sinuses lack smoothtively.Near the internal occipital protuberance, themuscles. The superior sagittal sinus is located in thesuperior sagittal, the occipital, the transverse sinusessuperior sagittal sulcus and the superior margin of theand the straight join together to form dilated commoncerebral falx, The straight sinus is situated in the con-pool called the confluence of sinuses.junction of the cerebral falx with the cerebellar tento-The sinuses of dura mater also communicate withrium.The sigmoid sinus,a lateral continuation of thethe extracranial veins through the emissary veins(-transverse sinus,is situated in the sigmoid sulcus andFig. VI-4-4), so an infection of the scalp can spread tois continuous with the internal jugular foramen.Thethe inside of the cranium.OptictractInterual carotid a.HypophysisOculomotorn.Trochlear n.Cavernous sinuOphthalmic n.Sphenoidal sinusAbducentnInternal carotid a.Maxillary m.Fig. VI-4-3 The cavernous sinuses(coronal section)The subarachnoid space over some places aroundthe brain is enlarged to form wide spaces called theII . Arachnoidsubarachnoid cisterns.The largest cerebellomedullarycistern lies between the caudal part of the cerebellarThe arachnoid mater is a delicate membrane en-hemispheres and the medulla oblongata,and is con-veloping the brainand spinalcordand lying betweentinuous with the spinal subarachnoid cavity. Thethe piamaterintermally and theduramaterextemallycerebellomedullary cistern isuseful place forpunc-itisseparaedfomthpiamaterby thesubarachnoidture to obtain cerebrospinal ffuid in clinic examina-space, which isflled withthecerebrospinalflud扫描全能王创建
.364.PARTVINERVOUSSYSTEMParietalemissaryvSuperior sagittal sinusSuperficial temposral v.Frontal emissaryInferior sagittal sinusCavermous sinusStraight sinus-Occipital emissaryv.-Transverse sinusSuperior ophthalmic vInferiorophthalmicvSup.and inf.petrosal sinusesAngularv.Occipital v.Pterygoid venous plexusSigmoid sinusFacial v.RetromandibularyExternal jugular v.Internal jugularFig.VI-4-4 The sinuses of dura mater and their communicationstion.These cisterns are the pontine cistern overtheThe arachnoid granulations(Fig. VI-4-5) are knobventral aspect of the pons, the interpeduncular cisternlike projections of arachnoid which protrude intoupe-between the two cerebral peduncles, the chiasmaticrior sagittal sinus and some other dural sinuses.Thecistem anterior to the optic chiasma,and theambientcerebrospinal fluidin the subarachnoid cavitypassescistern surrounding the midbrain. Most of these cis-through this thin membrane into the sinuses of duraterns can be visualized in pneumo cephalogram.mater and istaken upbythe venous blood stream.SkinSuperficial faciaEpicranial aponeurosisLoose connective tissuePeriosteumParietal emissary v.Parietal boneArachnoid granulatianSuperior sagittal sinusDuramaterPia mateSubarachnoid spaceCerebral cortexFig. VI-4-5 The arachnoid granulations and sinuses of dura mater扫描全能王创建
Chapter4Meninges, BloodVessels of Brain, Spinal Cord,and the Cerebrospinal Fluid 365The spinal subarachnoid space becomes widertery and the internal carotid arteryfrom the inferiorendofthespinalcord toabout thelevelfthesecondsacralvertbra, whichiscalledI.Vertebral arteryteminalcistemandcontainsthecaudaquinaItisthebest site foralumbar punctureduetoavoidingThe vertebral artery (a. vertebralis) (Fig. VI4-6) , isinjury to the spinal cord.the first branch of the subclavian, and arises from theupperandbackpart of thefirstportionof thevessel.II. Pia MaterIt is surrounded by a plexus of nerve fibers derivedfrom the inferior cervical ganglion of the sympatheticThe pia mater is a vascular membrane, consistingtrunk, and ascends through the foramina in the trans-of a minute plexus of blood vessels, Unlike the otherverse processes of the upper six cervical vertebrae, itmeninges, it closely attached to the surfaces of thethen winds behind the superior articular process of thebrain and spinal cord and follows into the fissures andatlas and, entering the skull through the foramen mag-sulci of the brain and spinal cord. It is divided intonum,unites,atthelowerborder ofthepons,withthethe spinal and cerebral pia mater. The ligamentumvessel of the opposite side to form the basilar artery.denticulatum(dentate ligament) is a narrow fibrousAt the upper border of pons, the basilar artery dividesband situated on either side of the medulla spinalisinto two posterior cerebral arteries, which supplythroughout its entire length, and separating the ante-most parts of the occipital and temporal lobes.Theriorfrom the posterior nerve roots.Itsmedial bordervertebral artery as well as the basilar artery sends theis continuous with the pia mater at the side of theanterior and posterior spinal arteries, the posterior in-medulla spinalis.Its lateral border presents a seriesferior cerebellar artery,the anterior inferior cerebellaroftriangular tooth-like processes, the points of whichartery, the superior cerebellar artery and the pontinearefixed at intervals to theduramater.These process-arteries to supply the medulla oblongata, pons and thees are twenty-one in number, on either side, the firstcerebellum.being attached to the dura mater,opposite themarginof the foramen magnum, between the vertebral arteryInternal carotid arteryand the hypoglossal nerve; and the last near the lowerend of themedulla spinalis.The intermal carotid artery rises from the commonAt certain sites of the cerebral ventricular walls,carotid artery,passes upward through the carotid ca-the cerebral pia mater and its blood vessels combinenal to enter the cranial cavity and passes through thewith the ependyma to form the choroid plexusescavernous sinus to the brain after giving off the oph-which are the main sources of cerebrospinal flu-thalmic artery. Its branches are the anterior cerebral,id(CSF)middle cerebral, and posterior communicating arter-Section 2 Blood Ves-ies. Internal carotid artery supplies the interior 2/3 ofcerebral hemisphere and thepart ofdiencephalon,andsels of Brain and Spi-the vertebral artery supplies the posterior 1/3 of cere-bral hemisphere,posteriorpart of diencephalon,brainnal Cordstem and cerebellum.Their branches to cerebellummay be divided into two groups: cortical branches andcentral branches, the former apply the cerebral cortexI .Arteries of Brainand the superficial part of the medullary substance,and the latter supply thebasal nuclei,internal capsuleSince the mode of distribution of the vessels ofand diencephalon etc.the brain has an important bearing upon a consider-1) Anterior cerebral artery (a. cerebri anterior)able number of the pathological lesions which mayarises from the internal carotid, at the medial extremi-occurin this partof thenervous system, itis importty of the lateral cerebral fissure. It passes forward andant toconsideralitlemore in detailthe mannerinmedialward across the anterior perforated substance,whichthevessels are distributedThe brainreceivesabove the optic nerve, to the commencement of thethe bloodfomwoairsofareres thevertebralarlongitudinal fissure. Here it comes into close relation-扫描全能王创建
·366·PARTVINERVOUSSYSTEMthe corpus callosum, and turning backward continueship withthe oppositeartery,to which it is connectedalong the upper surface of the corpus callosum to itsby a short trunk, the anterior communicating artery.posterior part, where they end by anastomosing withFrom this point thetwo vessels run sideby side inthe posterior cerebral arteries (Fig.VI-4-7, 8)the longitudinal fissure, curve around the genu ofOlfactory bulbOlfactorytractFrontal lobeOptic n.HypophysisTemporallobeInternal carotida.AnteriorOculomotornMiddle cerebral aTrochlearBasilaraTrigeminal rPosterior cerebraAbducent nAnteriorinferiorcerebellaraFacial nVestibulocochlearPosteriorinferiorcerebellaraGlossopharyngealCerebellumVaguriorspinalaHypoglossalAccessory1Spinal cordOccipital lobeIntemalLcarotidaAnteriorcerebralaAnteriorcommunicatingaMiddlecerebrala.PosteriorcommunicatingAnterior choroidalPosterior cerebral a.BasilaraSuperiorcerebellar aPontinea.Labyrinthinea.Anterior inferior cerebellara.Posterior inferior cerebellar a.Anterior spinal a.VertebralaFig. VI-4-6.The arteries at the base of the brain and the arterial circle扫描全能王创建
Chapter4 Meninges, Blood Vessels of Brain, Spinal Cord, and the Cerebrospinal Fluid -367.Parietal brFrontal br.Occipitalbr.Anterior cerebral a.Orbital br.Posteriorcerebrala.Temporal branchofmiddle cerebral a.mporalbrsFig. VI-4-7 The arteries on the medial surface of the cerebral hemisphere2) Middle cerebral artery (a. cerebri media),theleft hemisphere would result in motor aphasia. Itslargest branch of the internal carotid, runs horizontalcentral branches supply thecaudate nucleus,lentiformly to the lateral and then upward to the lateral sulcusnucleus and genu of the internal capsule.Due to thein which it courses laterally and backward and givesthin walls and thetortuous coursefits central branch-rise to cortical branches to supply most of the dorso-es,whenocclusions or increaseinpressureoccurslateral surface of the cerebral hemisphere includingsuddenly,there will be marked hyperemia and morethe somatomotor center, somatosensory center andor less extensive hemorrhages which may involve thelanguage centers.An occlusion of its ortical branch-internal capsule causing contralateral hemilegia andes may causecontralateral paralysis of theface andbinocularhemianopsia (Fig.VI-4-8)upper limbs. Damage in the motor speech area of theBranches of antericerebralaFrontalbranchesParietal branchesIteriorfrontal br.Middlecerebral a.Branches ofposteriorcerebral aTemporalbrsFig. VI-4-8 The arteries on the dorsolateral surface of the cerebral hemisphere3) Anterior choroidal artery runs along the opticand anastomoses with the posterior cerebral arterytractinferiorly and enters the inferiorhorn ofthe lat-eral ventricle to terminate in the choroidal plexues.It3.Cerebral arterial circle(willissupplies the geniculate body, posteroinferior part ofcircle)the posteriorlimb of the intermal capsule, and partofthe cerebral peduncle and globus pallidus.The cerebral arteries are derived from the internal4) Posterior communicating artery runs backwardcarotid and vertebral, which at the base of the brain扫描全能王创建
·368·PARTVINERVOUSSYSTEMformaremarkableanastomosisknown as thearterialtermed as the superficial cerebral veins and situatedcircle of Willis. It is formed in front by the anterioron the surface of the brain(Fig.VI-4-10) and draincerebral arteries, branches of the internal carotid,thebloodfromthecerebral cortextoemptyintothewhich are connected together by the anterior commu-adjacent sinuses of dura mater.They are divided intonicating; behind by thetwo posterior cerebral arteries,superior cerebral veins, middle cerebral veins and in-branches of the basilar,which are connected on eitherferior cerebral veins.sidewith the internal carotid bytheposterior commu-nicating.The parts of the brain included within thisarterial circle are, the optic chiasma, the tuber cinere-um,themamillarybody.Thebranches derived fromthe anterior, middle and posterior cerebral arteries,and from the cerebral arteries circle are divided intoCortical branchesthe cortical and the central branches (Fig.VI-4-9)-Head of thecaudateII.Veins of BrainnucleusDorsal thalamus-Intermal capsuleClaustrumTheveins ofthe brain possess no valves,and theirPutamenwalls, owingto the absence of muscular tissue,areGlobus pallidusextremely thin.Theypiercethe arachnoid membraneCentralbrs.and the inner or meningeal layer of the dura mater,Middle cerebral a.and open into the cranial venous sinuses. They maybe divided into two sets, superficial and deep groups.Superficial cerebral veinsFig.VI-4-9The central branches of cerebralarteriesThe superficial cerebral veins are commonlySuperiorcerebralvSuperior sagittalSuperior anastomotic vsinusInferioranastomoticy.uperficialmiddlecerebral a.Inferior cerebral v.Transverse sinusFig.VI-4-10The superficial cerebral veinsand great cerebral vein. The internal cerebral veinDeep cerebral veinsdrain the blood from deep structures, and terminate inthe great cerebral vein which empties into the straightThe deep cerebral veins include the internal vein.sinus.扫描全能王创建
Chapter4Meninges, BloodVessels of Brain, Spinal Cord, and the CerebrospinalFluid369terior spinal artery and posterior spinal artery of thevertebral artery, and also from the posterior intercos-II . Blood Vessels of Spinaltal artery and the lumbar artery (Fig. VI-4-11) . TheCordposterior spinal artery descends along the posterolat-eral sulcus, and the anterior spinal artery unites withThe blood of the spinal cord comes from the an-its fellow ofthe opposite side to form a trunk whichPosteriorcerebral a.Superiorcerebellar a.KBasilaraPosterior inferior cerebellaraPostespinalaVertebral a.Anterior spinar a.HHAscendingcervicalFlium terminalePosleriorsurfaceAnterior.surfaceFig. VI-4-11 The arteries of the spinal corddescends along the anterior median fssure to distrib-rior are formed by theunion of small spinal veins andute to every part of the spinal cord (Fig. VI-4-12)empty into the anterior and posterior radicular veinsThe names and distribution of the spinal veins arewhich drain into the internal vertebral venous plexussimlar to those of the arteries. The anterior and poste-which lies within the epidural space.扫描全能王创建
.370·PARTVIINERVOUSSYSTEMPosterolateral spinalPosteriorspinalvPosteriorspinal a.Sulcal a. and vCoronal a.of spinalcordPosterior radicular a.Anterior radicular a.Anterior spinal a.andvSpinal ganglionSpinal pia materSpinal arachnoid materRadicular a.Spinal dura materIntemal vertebralvenous plexusDorsal root sleeveFig.VI-4-12 The blood supply of spinal cordSection 3 Circulationthefourthventricles.The CSF is produced by the choroid plexuses ofof the Cerebrospinalthe lateral, the third and the fourth ventricles. TheFluidfluid drains from the lateral ventricles through theinterventricular foramina into the third ventricle thenThe cerebrospinal fluid CSF), for the most part through the cerebral aqueduct into the fourth ventri-elaborated by the choroid plexuses, is poured intocle, fluid escapes from the fourth ventricle throughthe cerebral ventricles which are lined by smoothits openings, the median foramen and two lateralependyma. It plays a role like lymph in the centralforamen, into the subarachnoid space, and from thenervous system. It has nutritive functions and servessubarachnoid space into the cerebral veins via theto remove the waste products of neuronal metabolismarachnoid granulations. Part of CSF flows from the(Fig. VI-4-13). CSF fills the ventricles, subarachnoidfourth ventricle to the central canal ofthe spinal cordspace and central canal of the spinal cord, and pro-An obstruction of the circulatory route causes thetects and cushions the central nervous system againstincrease of intracranial pressure and hydrocephalustrauma. The CSF can disperse the pressure on thein infants. The displacement of the brain tissue duebrain caused by a blow and regulate the intracranialto the elevated intracranial pressure, will cause a cepressure. There is no evidence that functional com-rebral hernia, such as the tentorial herniation and themunications between the cerebral ventricles and theherniation of the cerebellar tonsils,both of which aresubarachnoid space exist in any region except fromhigh risk for life.扫描全能王创建