《系统解剖学 Systematic Anatomy》课程教学资源（书籍教材）Chapter 5 PNS Section 2 Cranial nerves

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Chapter5 Peripheral Nervous System · 391 ·2) Perineal nerveIt runs forward beneath theCNXVagusnerveinternalpudendalsslsandisdistributedthCN XI Accessory nervemuscles ofthe perineum and the skinof the scrotumCN XIl Hypoglossal nerveThe Roman numerals indicate the orders in whichor the greater lip of pudendum.3) Dorsal nerve of penislelitoris It runs to thethe nerves are attached to the brain from cerebrum todorsumofthepenislclitorisIt suppliestheskinofthemedulla oblongata, whereas the names indicate thepenislitrisand the cavemous body.distributions or functions of them (Fig. VI-5-19).The cranial nerves, unlike the spinal nerves which(4) Superior gluteal nerve(L,-S,)all are mixed nerves, become more specialized.Threepairs（I,IIand v)of cranial nerves have only af-It leaves the pelvis via the greater sciatic foramenferent or sensory fibers and belong to the sensorysuperiortothepiriformis along withthe superiorglu-nerve.They conductthe impulses of olfaction,vision,teal vessels, and passes between the gluteus mediushearing and proprioception.Five pairs(II,IV,VI,XI and XI)of the cranial nerves have only efferent orand gluteus minimus(Fig. VI-5-15) . It supplies themotor fibers so named motor nerve.Four pairs(V,VIl,gluteus medius, gluteus minimus and the tensor fasci-IX and X) have both efferent and afferent fibers, andaelata.become the mixed nerve.There are two kinds of ganglion associated with(5) Inferior gluteal nerve(Ls-S2)the cranial nerves: the sensory ganglion, such as thetrigeminal, cochlear and vestibular ganglia, and theIt leaves the pelvis through the greater sciatic fo-parasympathetic ganglion, such as the ciliary, pteryramen inferior to the piriformis in company with thegopalatine, submandibular and otic ganglia.inferior gluteal vessels (Fig. VI-5-15) . It innervatesCranial nerves also contain elements that are notthe gluteus maximus and the skin over the lower partfound in spinal nerves besides containing those(theof the gluteal region.somatic afferent fibers,visceral afferent fibers, soQian Yihua（钱亦华）HuHaitao(胡海涛）maticefferentfibersandvisceral efferentfibers)con-tained in spinal nerves. Only in the head and neck isSection 2 Cranialthere muscle that develops from the wall of the phar-ynx, and the cranial nerves originally connected withNervesthe wall of the pharynx are therefore the only nervescontaining voluntary motor fibers to this type ofThere are twelve pairs of cranial nerves which areattached to the brain with receptors and effectors. Thevoluntary muscle.Those nerve fibers are sometimescalled special visceral motor fibers because the mus-cranial nerves issue from the brain and leave or en-cle they supply is not the usual type(smooth muscle)ter the cranial cavity through a series of foramina orthat develops from the wall of the gut. Further, somefissures in the base of the skull. Twelve pairs of cra-cranial nerves serve types of sensory organs that oc-nial nerves are commonly recognized and have beencur only in the head, and the fibers of these nerves aregiven both names and numbers; and Roman numeralsusually known as special sensory fibers. If they areshould be used. They are as follows:concerned primarily with the gut, as taste fibers are,CN I Olfactory nervefor instance, they are known as special visceral sen-CN II Optic nervesory(afferent) fibers, but if they are connected withCN II Oculomotor nervethe body as a whole, as are the fibers from the eye,CN IV Trochlear nervethey are known as special somatic sensoryfibers.InCN V Trigeminal nervesummary, the cranial nerves contain seven fiber com-CN VI Abducent nerveponents, but no a cranial nerve contains all the sevenCN VI Facial nervetypes of fbers that are found in all 12 of these nervesCN VI Vestibulocochlear nervecombined(Tab. VI-5-1) .CN IX Glossopharyngeal nerve扫描全能王创建

Chapter 5 Peripheral Nervous System · 393 ·Comparing to the spinal cord, the cranial nervesac muscle and glands) and innervate the activities ofcontain seven components generally:them.General somatic afferentSpecial visceral efferent fibersfibersThe special visceral efferent fibers originate fromThey distribute to the skin, skeleton muscles andthe brain stem. They supply the facial muscles, thetendons of the head and face, the eye, the mucosa ofmasticatory muscles and the muscles of pharynx andoral and nasal cavity, and conduct the impulses fromlarynx.them to some nuclei in the brain.According to the components and functions,thetwelve pairs of cranial nerves are divided into three2.Special somatic afferent fiberstypes:1) Afferent(or Sensory) nerve They are the ol-They distribute to the eyeball(retina) and the in-factory,the optic and the vestibulocochlear nerve,justternal ear, conduct the vision, hearing and balance tocontain the sensory fibers.thebrain stem.2) Efferent(or Motor) nerve They are the ocu-lomotor,thetrochlear,theabducent,theaccessoryandthe hypoglossal nerve, just contain the motor fibers..General visceral afferent fiber3) Mixed nerve They are the trigeminal, the fa-cial, the glossopharyngeal and the vagus nerves, con-They receive the visceral senses of viscus in headtain the fibers not only the motor but also the sensory.neck, thorax and most of abdomen, the heart andglands, and transmit the impulses to other nuclei orI . Sensory Cranial Nervesstructures in the brain.Special visceral afferent fibeiOlfactory nerve (CN I).They receive the smell and taste sensation fromthe nose and tongue respectively, and transmit theIt is a special visceral sensory nerve and com-signals to central nervous system.posed ofthe central processes of olfactory cell.Whichare of the primitive bipolar neuro-epithelial type, lo-cated in the mucous membrane ofthe olfactory regionSomatic efferent fibersof the nasal cavity;the olfactory region comprisesthe superior nasal concha and the upper part of theThey arise from certain nuclei in the brain stem innasal septum which is opposite to the superior nasalwhich the cell bodies are large or middle in size andconcha(Fig. VI-5-19, 20).Their central processes inmultipolar. These fibers supply the skeleton musclesthe nasal mucous membrane are collected into 15-20of the tongue and the extraocular muscles.olfactory filaments, which pierce the cribriformforamina of the ethmoid bone, and end in the olfacto-.General visceral efferentfibersry bulb. From the olfactory bulb, fibers of the mitralcells run backward in the olfactory tracts ultimately toreach the areas ofolfactory sense in the hippocampusThe cell bodies which give off these fibers areof the cerebrum.The olfactory nerve is pure sensory.located in certain nuclei of the brain stem. These fi-In severe injuries of the anterior cranial fossa, thebers belong to the parasympathetic nervous system.olfactory nerves may be torn. In the case, there is aAll these fibers end in the parasympathetic ganglialoss of the smell and the cerebrospinal fluid leaks intonear(or in) the visceral organs(smooth muscles, cardi-the nasal cavity.扫描全能王创建

.394·PARTVIINERVOUSSYSTEMCribriformplateofethmoidboneOlfactorybulbOlfactorySuperior nasal conchaFig. VI-5-20The olfactorynerveVestibulocochlear nerve (CNOpticnerve(CN I)It is a special somatic sensory nerve. The fibers,It has two well-defined parts, the cochlear(audi-which originate from the central processes of the gan-tory) and vestibular nerves-both sensory. Which areglionic cells of the retina, are converged on the opticthe special somatic sensory nerves conducting thedisc and pierce the eyeball at its posterior pole tohearing and equilibrium respectively. The fibers ofform the optic nerve.the cochlear nerve take origin from the neurons in theThe optic nerve goes posteromedially throughcochlear ganglion located in the cochlea. The centralthe posterior part of the orbital cavity. It then passesprocesses of the neurons pass through the internalthrough the optic canal into the middle cranial fossa,acoustic meatus to the pontocerebellar angle enterand joins the optic chiasma. Here the fibers from theinto the bulbopontine sulcus(Fig. VI-2-14) and termi-medial half of each retina cross to the opposite side,nate in the cochlear nucleus; the peripheral processesand those from the lateral half of each retina remainare distributed to the hair cells of the spiral organ. Theon the same side. From the optic chiasma the fibersvestibular nerve arises from the neurons of the ves-pass to the optic tracts from which the majority oftibular ganglion situated in the bottom of the internalthe fbers go to the lateral geniculate body. The opticacoustic meatus. Their peripheral processes terminatenerve is enclosed in three layers of coverings. Thesein the crista ampullaris and the maculae of the utriclecoverings and the spaces among them are continuousand saccule,the central processes pass into the brainwith those of the brain. So that, the meningitis maywith the cochlear nerve end in the vestibular nucleus.involve the eyes.Both ganglia contain bipolar neurons(Fig. VI-5-21,30) .扫描全能王创建

Chapter 5 Peripheral Nervous System · 395 ·Vestibular nucleiCochlear nucleiAnterior semicircularductFacial n.Vestivbularganglion55Lateral semicirculaductIntermalacousticUtricleCochlear n.meatusSacculeInferior olivary nucleusVestibularnCochlearganglionCochlearductFig. VI-5-21 The vestibulocochlear nerveThe vestibulocochlear nerve is frequentlybranch is given to the ciliary ganglion. This branchinjured together with the facial nerve at the pon-contains the parasympathetic preganglionic fiberstocerebellar angle by some tumors or in the casefrom the Edinger-Westphal nucleus, and synapseof an acoustic neuroma. Injuries of the internalwith the neurons of the ganglion. The postganglionicear may also cause the deafness and loss of thefibers take part in the short ciliary nerves to supplyequilibrium.the sphincter pupillae and ciliary muscles.Paralysisoftheoculomotornerveleadsto @ptosis,ordrop-ping of the upper eyelid; ②external strabismus,onII.Motor Cranial Nervesaccount of the unopposed action of the lateral rectusand superior obliquus;?dilatation ofthepupil andloss of power of accommodation on exposure to light,Oculomotor nerve (CN IIwhen parasympathetic nerve fiber was damaged at the(Fig.VI-5-22)same time.The ciliary ganglion is a parasympathetic gangli-It is a motor nerve and contains somatic and gen-on and situated between the optic nerve and the lat-eral visceral efferent (parasympathetic) fibers, Theeral rectus near the apex of the orbit (Fig. VI-5-22) .somatic efferent fibers arisefrom the oculomotor nu-The parasympathetic preganglionic fibers are relayedcleus. The general visceral efferent fibers arise fromin the ganglion. The postganglionic fibers supply thethe accessory oculomotor nucleus (Edinger-Westphalsphincter pupillae and ciliary muscle.nucleus).Both nuclei are located in mesencephalon(Fig. V-2-18) .Trochlear nerve (CN V)The oculomotor nerve emerges from the interpe-duncular fossa of midbrain and traverses the lateralIt is a somatic motor nerve and supplies the su-wall of the cavernous sinus, where it lies above theperior obliquus (Fig.VI-5-22,23,24).It arises fromtrochlear nerve (Fig.VI-5-22). It is then divided intothe trochlear nucleus and emerges from the superiorthe superior and the inferior branches, which enter themedullaryvelum immediatelybelow the inferior col-orbit through the superior orbital fissure. The smallerliculus.The nerve winds forward round the cerebralsuperior one ascends on the lateral side of the opticpeduncle,then passesforward inthe lateral wall ofnerve, and supplies the superior rectus and the leva-the cavernous sinus enters the orbit through the supe-tor palpebrae superioris. The inferior one goes to therior orbital fissure. The trochlear nerve passes medial-inferior rectus, medial rectus and inferior obliquus.ly and finally enters the superior obliquus.From the nerve to the inferior obliquus a short thick扫描全能王创建

Chapter 5 Peripheral Nervous System · 397 :it. The result of the damage of abducent nerve is thesuperior orbital fissure.Finally the nerve enters intoparalysis of the lateral rectus and medial squint.the medial surface of the lateral rectus and supplies1Anterior cerebral Opticn.IntermalcarotidaOculomotornCavernous sinusAbducentnTrigeminal ganglionPosterior cerebral aSuperior cerebellaRootoftrigeminal n.Superior petrosal sinusSubstantia nigraTrochlear n.Red nucleusMidbrainFig.VI-5-24 The nerves passing through the cavernous sinussupply it.Unilateral lesionofaccessorynerveusually doesAccessory nerve(CN XI)not produce an abnormality in the position of thehead. However, weakness in turning the face to theIt is a special visceral motor nerve, formed by theopposite side can be detected due to the stermocleido-union of the cranial and spinal roots.The smaller cra-mastoid paralysis.Unilateral paralysisofthe trapeziusnial root arises from the lower part ofthe nucleus am-mayproduce dropping of the shoulder.In fracturesbiguus and emerges from the posterior olivary sulcusor other injury involving the jugular foramen, theof the medulla below the rootlets of the vagus nerveglossopharyngeal, vagus and accessory nerves mayby 4-5 rootlets. The cranial root passes through thebe damaged together. The symptoms and signs of thisjugular foramen and joins the vagus nerve immediate-condition is called the jugular foramen syndrome orly to supply the muscles of the pharynx and the lar-Vernetsyndrome.ynx. The larger spinal root arises from the accessorynucleus in the anterior horn of the upper 5-6 cervical5.Hypoglossalnerve(CN XIl)segments of spinal cord. It emerges from the spinalcord by rootlets between the anterior and posteriorThe hypoglossal nerve is a somatic motor nerverootlets of the spinal nerves. The spinal root ascendsand arises from the hypoglossal nucleus (Fig. VI -2-22).and enters the skull throughtheforamen magnumIts 10-15 rootlets emerge from the anterior side of me-unites the cranial root to form the accessory nerve(Fig. VI-5-25). It then passes upward and laterally todulla oblongata between the olive and the pyramid bythe jugular foramen, where it passes backward andway of a number rootlets.The rootlets unite to leavedownward to the neck. After emerging out the spinalthe skull through the hypoglossal canal. The nerverootgoesto the sternocleidomastoid,which it piercesdescends between the internal carotid artery and the.internal jugular vein. At the level of the angle of theand supplies, and then crosses the posterior triangle ofmandible it passes forward over the internal and ex-the neck to enter the deep surface of the trapezius and扫描全能王创建

.398.PARTVINERVOUSSYSTEMaspect of the genioglossus and is continued forwardsternal carotid arteries and gives off its descending(su-in its substance as far as the tip of the tongue, dis-perior root of ansa cervicalis) and thyrohyoid branch-tributing branches to its muscular substance. The hy-es.Then it inclines upwards as it runs forwards on thepoglossal nerve supplies all the extrinsic and intrinsichyoglossus muscle,passing deep to the tendon ofthemuscles ofthe tongue (Fig. VI-5-26).digastric, the stylohyoid and the posterior border ofthe mylohyoid muscle. It passes next on to the lateralGlossopharyngeal n.Accessory n.Vagus n.Dorsal nucleusofvagusn.OCranial root.Spinal rootNucleusambiguusaOCNucleus ofaccessory n.Oo0Fig.VI-5-25The schematic diagram of two roots of accessory nerveInjury to the hypoglossal nerve results in paral-trigeminal nerve to supply the masticatory muscles,ysis and atrophy of the muscles of the affected sidemylohyoid,anterior belly of digastric,tensor veliof the tongue; the protruded tongue deviates to thepalatini and tensortympani.Thetrigeminal nervehasparalyzed side because of the action of the unaffectedtwo roots placed close together on the ventral lateralgenioglossusis normal.surface of the pons: a large sensory root which arisesfrom the sensory nucleus of the trigeminal nerve andhas a larger semilunar ganglion and a small motorII.Mixed Cranial Nervesroot. From the semilunar ganglion the three branchesradiate forward.The sensory root contains the general somaticTrigeminal nerve(CN V)afferentfibers and is madeupofthecentral processesof neurons which are located in the trigeminal gan-The trigeminal nerve is a mixed nerve and theglion. After the sensory fibers entering into the pons,largest one of the cranial nerves and as its namethese fibers end in the pontine nucleus of trigeminalsuggests has three large branches, the ophthalmic,nerve and the spinal nucleus of the trigeminal nerve.maxillary,and mandibular.It is attached to the con-The trigeminal ganglion is a semilunar dilatationjunction of the basilar part of pons and middle cere-of the nerve, it occupies thetrigeminal impressionbral peduncle. It is entirely sensory except for a smallnear the apex of the petrous part of the temporalmotor branch which joins with the mandibular branchbone and is situated in the side of the cavernous si-and supplies the muscles of mastication.The smallernus (Fig. V-5-19, 27) . The neurons of the ganglionmotor root contains the special visceral efferent fibersare pseudounipolar, their central processes form thewhich arisefrom themotor nucleus of thetrigem-sensory root to enter the pons, and their peripheralinal nerve and take part in the third division of theprocesses converge into three divisions of the tri-扫描全能王创建

Chapter 5 Peripheral Nervous System ·399meninges, and conduct the pain, thermal and crudegeminal nerve which are distributed to the skinofthetouch sensation of them. Their distribution in the faceface, the mucous membranes of the eye, tongue, oralis limited by the fissures of the eye and the mouth.cavity, nasal cavity and the paranasal sinuses as wellas the teeth, the eyebal, the lacrimal gland and theGlossopharygeal nExt.br.ofaccessoryn.Hypoglossal n.Carotid sinus br.Superior root ofansa cervicalisagusn.-Inferiorrootofansa cervicalisAnsa cervicalisFig. VI-5-26 The glossopharyngeal, accessory and hypoglossal nerveswhich distributes to the skin near the medial angle ofThe three divisions of the trigeminal nerve are theeye and back of nose. The former passes through theophthalmic nerve (CN V,), the maxillary nerve (CNsupraorbital notch and the latter leave the orbit medialV2) and the mandibular nerve (CN V,) .to the supraorbital notch.2) Nasociliary nerve It passes forwards and(1) Ophthalmic nerve (Fig. VI-5-22, 23)mediallybetween the superior rectus and optic nerve,it sends out long ciliary nerves which penetrate intoIt is a sensory nerve and is the smallest division ofthe eyeball and distribute the cornea,ciliary body andthe trigeminal nerve. It goes forwards along the lateralthe iris; and sends out the anterior and posterior eth-wall ofthe cavernous sinus, enters orbital cavity pass-moidal nerves to supply the ethmoidal sinus, the mu-ing through the superior orbital fissure. Before goingcous membrane of nasal cavity and the cerebral durainto the orbit, it is divided into three branches(themater; its terminal branch is called the infratrochlearfrontal, nasociliary and lacrimal nerves) . They arenerve which distributes to the lacrimal sac, the skin ofdistributed to the cerebral dura mater, orbit, eyeball,eyelids, back of nose. It also gives off a branch whichlacrimal gland, conjunctiva, the part of mucous mem-is the sensory root to the ciliary ganglion.brane of nose and skins of the forehead, upper eyelid3) Lacrimal nerve It runs forward and later-and the back of nose.ally along the superior border of the lateral rectus,1) Frontal nerve It is the largest branch of theand gives off several filaments to the lacrimal glandophthalmic nerve. It enters the orbit and runs for-Finally it ends in the skin of the upper eyelid and thewards above the levator palpebrae superioris.Aboutlateral angle of eye.The parasympathetic fibers com-midway between the apex and the base of the orbiting from facial nerve join it by the communicatingit divided into a large supraorbital nerve which dis-branch of the zygomatic nerve and control the secre-tributes to the skin of forehead, anterior part of thetion of the lacrimal gland.scalp and upper eyelid and small supratrochlear nerve扫描全能王创建

·400·PARTVINERVOUSSYSTEMInfraorbital nPosterior superior alveolar br.Pterygopalatine ganglionOphthalmic nMaxillarynTrigminal n.Trigeminal ganglionMandibularnAnterior andmiddle superiorMiddle menin geal aalveolarbrs.Facialn.Auriculotemporal n.Buccal n.Superior dental plexusChorda tympaniInferior alveolar n.Lingual n.Mylohyoid n.Sublingual glandMental n.Sympathetic plexusaround thefacial a.Extermal carotid a.SubmandibularganglionSubmandibular glandFig.VI-5-27The branches of trigeminal nervecontain somatic afferentfibers,which come from the(2) Maxillary nerve(Fig. VI-5-22, 27)maxillary nerve in the pterygopalatine fossa, and en-ter the posterior surface of the maxilla.The anteriorIt is a sensory nerve. It begins at the trigeminaland middle branches are given off from the infraorbit-ganglion, and passes forwards along the lower partal nerve respectively in the infraorbital groove and theof the lateral wall of the cavernous sinus. When theinfraorbital canal.Thesebranches communicate withnerve emerges out from the skull through the forameneachotherandfomthesuperiordental plexustosupplytherotundum, it crosses the upper part of the pterygopal-maxillary sinus, the upper teeth and gum(Fig. VI-5-27).atine fossa, and enters the orbit through the inferior3)Zygomatic nerveIt arises from the maxillaryorbital fissure continues as the infraorbital nerve(-nerve in the pterygopalatine fossa, enters the orbitFig. VI-5-28).The maxillary nerve supplies the cere-through the inferior orbital fissure, pierces the lateralbral dura mater, the skin between the fissures of thewall of the orbit. It distributes to the skin over part ofeye and the mouth, the upper teeth and the mucousthe zygomatic area and temple. The communicatingmembranes of the nasal and oral cavity(Fig. VI-5-29).branch ofit with the lacrimal nerve contains parasym-Its mainbranches areasfollows:pathetic postganglionic fibers which arise from the1) Infraorbital nerveIt is the largest and a ter-pterygopalatine ganglion to supply the secretion ofminal branch of the maxillary nerve. After traversinglacrimal gland (Fig. VI-5-22, 27).the inferior orbital groove and canal, it appears on the4) Pterygopalatine nerves (Fig. VI-5-27) Theyface through the infraorbital foramen to distribute toare two or three delicate filaments and have somaticthe lower eyelid, the ala of the nose and the upper lip.afferent fibers which go downward join the pteryg-2) Superior alveolar nerves They are the an-poalatine ganglion and pass by the maxillary nerve,terior,middle and posterior branches.The posteriorto supply the mucous membrane of the nasal cavity,superior alveolar branches are 2 or 3 in number andpalatine and the palatine tonsil.扫描全能王创建

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