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
·392·PARTVINERVOUSSYSTEMTab.VI-5-1 The origin and passage of the cranial nerveName and orderPassage of the skullPortion conncctingwithbrainI Olfactory nerveCribriform foraminaOlfactorybulbII Optic nerveOpticcanalOptic chiasmaII Oculomotor nerveSuperior orbital fissureMedial side of the cerebral peduncleIVTrochlear nerveSuperior orbital fissureThe superior medullary velumSuperior orbital fissure(ophthalmic nerve)VTrigeminal nerveThe junction of basilar part of pons and theForamen rotundum(maxillary nerve)middle cerebellar peduncleForamen ovale(mandibular never)VAbducent nerveSuperior orbital fissureMedial part of the bulbopontine sulcusFacial canalVI Facial nerveLateral part of the bulbopontine sulcusVI Vestibulocochlear nerveInternal acousticmeatusLateral part ofthe bulbopontine sulcusIX Glossopharyngeal nerveJugularforamenUpper part of the sulcus behind the oliveX Vagus nerveJugular foramenMiddlepart of thesulcus behind the oliveXI Accessory nerveJugularforamenLower part of the sulcus behind the oliveXI Hypoglossal neverHypoglossal canalAnterolateral sulcusofmedullaoblongataTrochlear n.Abducent n.OlfactorynOculomotorn.Ophthalmic n.OpticnMaxillary n.Mandibularn.Facial nestibulocochlearnGlossopharyngeal n.Hypoglossal nVagusn.Extemalbr.ofaccessoryFig. VI-5-19The schematic diagram of the cranial nerves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