PARTIV SENSORY ORGANSChapter1 Visual OrganNV.Extraocular MusclesSection1 EyeballV.Connective Tissue in the OrbitI.Shape of EyeballSection 3 Blood Vessels and Nerves of EyeII. Structure of EyeballI.Arteries of EyeSection 2Accessory Organs of EyeII. Veins of EyeI.EyelidsII. Nerves of EyeII.ConjunctivaII.Lacrimal ApparatusChapter2VestibulocochlearOrganSection1 Extemal EarII.MastoidantrumandAirCellsI.AuricleSection3Internal EarII.Extemal Acoustic MeatusI.BonyLabyrinthII.TympanicMembraneII.Membranous LabyrinthSection2MiddleEarII.Internal AcousticMeatusI. Tympanic CavitySection 4 Sound Conduction PathwaysII. Auditory TubeIntroductionSensory organs include the receptors and their accessoryorgans.The receptors receive the stimulationfrom theexternalor internal environmentofthe body,and convert it intothenerve impulse.Accordingtothepositionofthereceptors andtheoriginofthestimulation,thereceptorsmaybedivided intothreekinds.() ExteroceptorsThey lie in the skin, the mucous membrane of the nasal cavity,paranasal sinusesandoralcavityandthevisual and auditoryorgans.Theyreceivestimulisuch astouch,pain,temperaturelight and sound from the external environment.(2) ProprioceptorsThey lie in the muscles,tendons, joints, ligaments and the internal ears, and receivestimuli about themovement ofthelimbs andtrunk,and thestimulation about thequilibrium(3)EnteroceorsTheylieinthe wllof viscera,and blood vessels, and acce the physical andchemical stimulation from the internal environment.·254·扫描全能王创建
Chapter 1Visual OrganThe visual organ consists of eyeball and accessorySection 1 Eyeballorgans ofeyeball.The eyeball can receive stimulationof light and transform it into the nerve impulse whichThe eyeball lies in the anterior part of the orbit,is conducted through the visual pathways to the visualembeddedinthefattissueoftheorbit,and enclosedcenter in the brain. The accessory organs include theinafascial sheath(capsule of Tendon)which sepaeyelid, conjunctiva, lacrimal apparatus extra ocularrates itfrom the orbital muscles and fat (Fig.IV-1-1)muscles, the connective tissue in the orbit and so on.Frontal sinusLevatorpalpebraesuperiorisSuperiorconjunctional fonSuperiorrectusSkinSubcutaneoustissueAdiposebodyoforbitOrbicularisoculiOpticnTarsusLateral rectusPalpebral conjunctiva更儿Sheath of eyeballEyelashTarsal glandEpiscleral spaceBulbar conjunctivaInteriorrectusWInferior conjunctival fomiMaxillaryn.0InferiorobliquusPosteriorbr.of2superioralveolarn.Maxillary sinFig,IV-1-1 The position of eyeballjoining the center of the pupil and the fovea centralisof the retina is called optic axis.The optic axis andI.Shape of Eyeballocular axis decussate sharply.An imaginary line en-circling theeyeball,midwaybetween the anterior andThe eyeball is about 2. 5 cm in diameter and isposterior poles, is the equator.spherical in shape, but it is not perfectly spherical, forthe anterior part ofit has asmallerradius of curvatureII-Structure of Eyeballthan therestofthe eyeball. (Fig.V-1-2)The centralpoints of the anterior and posterior surfaces ofeyeballare known as the anterior and posterior poles. TheThe eyeball comprises the wall of the eyeball andlinjoiningthewlestularxshlinthe contents enclosed by it (Fig. IV-1-2)·255·扫描全能王创建
·256.PARTIVSENSORY ORGANSPupilSphincter pupillaeCorneaAnterior chamberIridocomeal angleIrisSinus venosus scleraPosterior chamberLensCiliary bodyScleraChoroidRetinaHyaloid canalEye axisOpticaxisVitreous bodyMacula luteaOpticdiscOpticnCentrala.&VofretinaFig. IV-1-2 The sectional anatomy of the eyeThe external surface of the sclera is in contactwiththeinner surfaceof thefascial sheathof eyeball,Walls of eyeballand the inner surface of it is loosely attached to thechoroid by some delicate pigmented areolar tissue,It consists of three coats,from outside inwards,but firmly adherent to the ciliary body.which are the fibrous tunic, the vascular tunic and theThe point where the optic nerve pierces the scleraretina.is approximately3mmtothenasal sideof theposteri-or pole oftheeyeball,andpresentsthe cribriform ap-(l)Fibrous tunicorexternal tunicpearance and is named the cribriform plate of sclera,which is a weakened point of the sclera.It consists of the cornea in front and the sclerabe-The junction of the sclera and the cornea is calledhind.limbus cornea and, close to it there is a circular canal1)CorneaThe cornea is the anterior 1/6of thein the internal part of the sclera, the sinus venousfibrous tunic of the eyeball. It is transparent and moresclera which drains the aqueous humor.highly curved, through which the light enters the eye.The sclera plays an important role for maintainingThe cormea is a nonvascular structure.but numeroustheform of the eyeball and protecting the contentssensory nerveterminals supply it,which makes itwithin it.very sensitive to pain and touch stimulation.2)Sclera It is the posterior5/6of the outer coat(2) Vascular tunicofthe eyeball which consists of densefibrous con-nective tissue and is white in color and opaque. It isIt is the middle coat, and consists of the iris thecontinuous with the cornea anteriorly and connectedciliary body and the choroid. This layer contains nu-with thefibrous sheath of the opticnervebehindmerous blood vessels and pigment cells and is brown扫描全能王创建
Chapter1 Visual Organ ·257.nosfnctiopovdhnutitioits center is a round aperture named pupil which con-tissues inside the eyeball.trols the amount of light reaching the retina.The free1) Iris (Fig. IN-1-3) It is the most anteriormargin of the iris is called papillary margin and itscolored part of the vasculartunic, and isa circularcircumference is continuous with the ciliary body.perforateddiaphragm withcoronary position.Nearcorneadilator pupillaetrabecular reticulumanterior chambersinus venosus scleraeirisiridocormneal anglesphincter pupillaeciliary musclelens nucleusscleracortexoflensposterior chamberchoroidciliary zonuleFig. IV-1-3 The iris and ciliary bodyand sclera.It is divided into the anterior part, ciliaryThe iris varies greatly in color, it is light blue inprocesses consisting of a number of 60-80 radial ridgwhite,browninChineseandverydarkbrowninblackes, and the posterior part, the ciliary ring, which ispeople.The color of iris is determined by the numbermoresmooth.In thehorizontal plane of theeveballofmelanophores,whichcontainmelaningranules.The iris contains two sets of smooth muscles.Thetheciliary body presentsa triangle in shape.its apexcircularly arranged muscle fibers form the sphincterrunsposteriorly andcontinueswith thechoroids,andits base faces forwards in which the iris insert.papillae which lie in the papillary margin of the iris.The radially arranged musclefiber is called the dilatorThe ciliary body contains involuntary muscles,papillae which pass towards the periphery of the iris.the ciliary muscles which are arranged into threegroups, meridional, radial and circular fibers. TheyThe pupil is decreased in size by the sphincter papil-can regulate the degree of the curvature of the lens forlaeand dilatedby thedilatorpupillaeclose and distal vision.Nerve supply: The parasympathetic nerve inner-The ciliary processes secrete the aqueous humor,vates the sphincter papillae, and the dilator pupillae iswhich supplynutritionforthecornea and lensandtosupplied by the sympathetic nerve.maintainthenormal intraocularpressure.The iris incompletely divided the space between3) Choroid It is the largest part of the middlethe cornea and the lens into the two parts: the anteriorchamber and the posterior chamber. The peripheralcoat and lies between the sclera and the retina (Fig.IV-1-2).It extends as farforwards as the-ora serrata ofpart of the anterior chamber is called the iridocornealthe retina, and occupies posteriortwo thirds of theangle or anterior chamber angle. The anterolateralvascular tunic.it is thickest posteriorly,where it iswallof the angle is made up by trabeculae, which ispierced by the optic nerve,and become thinner ascalled the trabecular reticulum. The space betweentrabculaearetermed the spaceofiridocomealangleit approaches the ciliary body.It is connected withsclera by some delicate areolar tissue the deep surface(Fontanasspace)whichitheery mporant pathof the choroid is connected with a layer pigmentedofaqueous humor circulation.cells which belong to the retina.2) Ciliary body (Fig. IV-1-3, IV-1-4) It lies attheiersuraceofthejunctionbeweentheoa扫描全能王创建
.258·PARTIVSENSORYORGANSCiliary.zonuleIrisOra serratePupilRetinaCiliaryprocessesLensChoroidCiliaryringScleraFig.IV-1-4Theciliarybodypart at the posterior border of the ciliary body. It be-The choroid contains rich pigment cells and ves-comes thinner graduallyfrom the optic disc to the Orasels,and supplies the nutrition for outer layer of reti-na.serrata.Near the center of the posterior part of theretina,there is an oval yellowish area, named the macula(3) Retina (the inner tunic)lutea(Fig.IV-1-5),it contains a small central pit, thefovea centralis,where visual acuity is highest.It is the neural sensory stratum. It lines the inter-About 3.5mmto thenasal side of themacula lu-nal surface ofthe vascular tunic,and is divided intotea, the optic nervepierces the retina and forms thethree parts from behind forwards:the optic part (parsopticdisc withadiameterof about 1.5mm,which isoptica),the ciliarypartand iridialpart (part iridica)The iridial and the ciliaryparts areknown as theblinda light, whitish disk with a central flat depressionpartbecauseof lacking light sensitive elements of theThe center of thedisc is pierced by the central arteryretina.and vein of the retina.The optic disc is insensitiveThe optic part of retina lines the internal surfaceto light, and termed the"blind spot".On ophthalmo-ofthe choroidand extends from the optic disc to thescopic examination,thenormal disc is seen to bepinkOra serrata which is the irregular edge of the opticduring lifeSuperior nasal arterioleofretinaSuperior temporalarterioleof retinaOpticdiscFoveacentralisMaculaJuteaInferiornasalarteriole of retinaInferiortemporalarteriole of retinaFig. IV-1-5 The fundus of the eyeball扫描全能王创建
Chapter1 Visual Organ·259.TheretinaonsssowolyeranouterpigThe nervous layer can be divided into three cellmdylayers: the outmost are the light sensitive rods andreopilaoaseraarcons (phooreceptors)，the innermostaretheganglionrayersmgowngetheHenethenouslayercells whoseaxonsform the optic nerve,and themidaidacmmnyredle layer are the bipolar cells which connect the rodsdaurng lifeand resulsin the retinodialyssand cones to the ganglion cells. (Fig. IV-1-6).HGangliorBipolarcellsRod cellsCone cellsPigmentepitheliumFig.IV-1-6The structure of retina (optic part)processes,from which it inters the posterior chamberthen it passes into the anterior chamber through pupilContents of the eyeballandescapes fromtheiridocorneal angleintosinus ve-nous sclerae (Fig. IV-1-3) through the space of irido-The contents of the eyeball include the aqueouscorneal angle,and finally,drains into the ophthalmichumor, the lens and the vitreous body (Fig.IV-1-2)veins via anterior ciliary veins.They are all transparent and avascular, and with thecornea altogether form the refractive media. Each(3) Lensplays a part in refracting the light entering the eye.It lies between the iris and the vitreous body.It(1) Chamber of eyeis atransparentand elastic,biconvex bodylackingbloodvesselsandnerves,andtheconvexityofitsan-It is the space between the cornea and the lens, itterior surface is less than that of its posterior surface.isflled with aqueous humorand isdivided incomAelastic membrane which surrounded the lenspletely into the anterior and the posterior chamberscloselyis known as the lens capsule.Thelens isby the iris.The anterior and the posterior chambersattached to the inner side of the ciliary processescommunicate through the pupil.by the ciliary zonule (or suspensory ligament).Theshape of the lens is maintained by the tension of the(2) Aqueous humorciliary zonule.During near vision, the ciliary musclecontracts,it pulls the ciliarybody anteriomedially,resss,trartanwaeydlaxes the ciliary zonule,and allows the elastic lens tothchmbrsothymdyvraincrease its convexity,thus shortening thefocallengthpoanddifunmtheapilariesthcilay扫描全能王创建
·260·PARTVSENSORYORGANSSection 2 Accessoryand bringing nearobjects into sharpfocus on thereti-na.Whileduringfar vision,thecondition isreversed.Organsof EyeThe elasticity of the lens decrease with age andresults in decrease of dioptric range, thus focusing onTheaccessoryorgansoftheeyeincludetheeyenear objects becomes progressively more difficult,lid,conjuntiva,lacrmalappara,xrauarwhich is known as presbyopia. In the aged, the lensmuscles and the fasciae within orbit.may also becomes opaque termed senile cataract.I.Eyelids(4)VitreousbodyThey consist of the upper and lower eyelids (orIt is a colorless, transparent and jelly-like bodypalpebrae) (Fig. IV-1-7), The gap space between thewhich flls the posteriorfour-fifths of the eyeball (thetwoeyelids istermed thepalpebralfssure, whosemevitreous chamber).The vitreous body is condenseddial and lateralend arerespectivelytermedthe medialsuperficially to form a transparent envelope,the vit-and lateral angle of the eye.the medial angle ofthereous membrane.Aminute canal runs through it fromeye presents wider prolongation called lacrimal lacusthe optic disc to the posterior surface of the lens,andsurrounding the lacrimal caruncle.On the medial endrepresents the remains of a branch of the central ar-of the margin of each eyelid, there is a small conicaltery of the retina (haloid artery)which supplied thedeveloping lens in the fetus, but which subsequentlyelevation termed the lacrimal papilla.Aminute open-disappeared.ing on the summit of thepapilla isknown as thelacri-The vitreous body abuts on the retina,ciliarybodymal punctum(Fig.IV-1-8)and the lens which forms the deep haloid fossa on theThe eyelashes are attached to the free edge ofanterior surface of the vitreous.The vitreous bodythe eyelids.The ciliary glands (gland of Zeis)are arplays the supporting role for the retina. The retinodi-ranged in rows insidethe freemargin of each eyelidalysismay occur,when this supporting role is weakand open near the attachments of the eyelashes.In-ened.flammation of these glands isknown as the stye.UppereyelidBulbar conjunctivaLacrimal caruncleLateralangleofeyMedial angle of eyenLowereyelidFig. IV-1-7The eyelidsThe eyelids consist of the following layers fromcularis oculi, which may close the palpebral fssurewithout inwards (Fig.IV-1-1):skin, super fascialwhen contracting. The upper eyelid is elevated by thefascia,muscular layer,tarsus,and conjunctiva.Thelevator palpebrae superioris muscle whose origin isskin of the eyelids is very thin, the superficial fasciaat the upper margin of the optic canal. Its tendon ex-is loose and devoid offat, It allows the skin to movepands into a wide, thinsheet and inserts into the skinfreely over the eyelids, and can become greatly swol-and upper margin of the superior tarsus muscle. Thelen with fluid or blood afteran injury.deep lamellaofthelevator palpebraesuperiorisconThe muscular layer is the palpebral part of orbi-tains the involuntary muscle fibers termed the superi-扫描全能王创建
Chapter1 Visual Organ ·261 .ortarsalis muscle (alsocalled Millermuscle) whichembedded in deep oftarsus, and open on the marginisattachedtotheuppermarginsuperiortarsusheofeyelids.Their secretion ensuresthe airtight closuretarsi arefomedbydenseconnectivetisuewhichexof the eyelids.A swelling of the eyelid because oftend from thefree margins ofthe eyelids and stiffenthe retained secretion ofthese glands is known as thethem (Fig. IV-1-8),The tarsal glands (ofMeibom)arechalazion.Lacrimal punctumUppertarsusicrimalductuleMedial pelpebralLacrimal gland.ligamentLacrimalsacLateral palpebralligamentLowertarsusOrbitalserNasolacrimalductFig.IV-1-8 The lacrimal apparatusgland and the lacrimal passage (Fig. IV-1-8)II.Conjunctiva1.Lacrimal glandThe Conjunctiva is a thin and transparent mucousmembrane which covers the anterior surface of theIt lies in the lacrimal fossa of the orbit, and itseyeball (bulbar conjunctiva)and lies the deep surfaceexcretory ducts open into the superior fornix of theof the eyelids (palpebral conjunctiva)The reflectedconjunctiva sac.The secretion of lacrimal gland (tears)parts of the conjunctiva from the superior and inferiorflows over the anterior surface of the eyeball, andeyelids onto the eyeball are respectively named thecollects eventually in thelacrimal lacus of themedialsuperior and inferior conjunctival fornices (Fig. IV-1-angle of theeye to the lacrimal punctum and then1).The palpebral conjunctiva isfirmly attached totheenter the Lacrimal Passages.The tears contain specialtarsi but the bulbar conjunctiva is loosely attached toenzyme dissolving bacteria,help to removethefor-the scleraThescular spaceformedbytheconjunceign material and moist thefront surfaceofeyeball.tiva is named the conjunctival sac, which is closedwhentheeyeisshut, itopen totheexteriorthrough2元Lacrimal passagesthepalpebralfssureand intothelacrimalsacthroughthe canaliculi.1) Lacrimal punctum They lie on the summitofthe lacrimal paplla which lie on themedial endsofIII.Lacrimal Apparatusthe free margin of each eyelid. It leads into the lacri-mal ductile.The Lacrimal apparatus consists of the lacrimal2)Lacrimal ductile (canaliculi)Theyfirst run扫描全能王创建
262.PARTIVSENSORYORGANS4)Nasolacrimalducttisamembranous canalupward ordownward respectively andthen turnto theabout8mmlong,Itextendsfromthlowerparmedial at a right angle, join and open into the lacrimalthelacrimalsac,anddescends inthnaslacrimalasac.Each ductulus is about 1. Ocm long.nal to the anterior part of inferior nasal meatus.3) Lacrimal sac It is lodged in the fossa forlacrimal sac situated in the anteriorpart of the medialIV.Extraocular Muscleswall of the orbit.The medial palpebral ligament lieanterior to its upper part.The superior end of the lac-rimal sac is blind,and its inferior end continues withThe extra ocular muscles include the four rectusthe nasolacrimal duct. The contraction of orbicularismuscles, two oblique muscles and the levator palpeoculi may dilate this sac,thus the tears is sucked intobrae superioris muscles (Fig. IV-1-1, 9)the lacrimal sac via the lacrimal ductule.LevatorpalpebraesuperiorismSuperior obliquusSuperiorrectusmMedial rectusmOpticn.Commontendinous ringLateral rectusmInferiorobliquusInferiorrectusmTo superolateralSuperior rectusm.(inferiorobliquus)Superior obliquusTosuperomedialA4(superiorrectusm)LateralrectusmTomedialTolateral(medial rectus m)(lateral rectus)Medial rectusmTo inferolateralInferior obliguusTo inferomedial(superior obliquus)(inferiorrectusm.)Inferior rectus m.Fig. IV-1-9The extra ocular musclemuscle runs forwards along the medial to the opticnerve, and the lateral rectus muscle passes anterolatFour rectus muscleserally lateral to the optic nerve. Their fat tendon areinserted into the sclera about 0.5-lcm from the mar-They arise from a common tendinous ring whichgin of the cornea. The medial rectus muscle turns thesurrounds the optic canal.The superior rectus muscleanterior pole of the eyeballmedially and the lateralpasses anterolaterally above the optic nerve and thersmuesiatrally,urirsmueeyeball; the inferior rectus muscle runs in the sametusthyball supomdiallyandtheinrrdirection below the optic nerve. The medial rectus扫描全能王创建
Chapter1 VisualOrgan·263.pose body is bordered by the orbital septum whichtus turns the eyeball inferomedially.is stretched fromthetarsi to the margins of the orbit.The eyeball is embedded in this adipose tissue but is2. Two oblique musclesseparated fromitbya thinmembranous sac,namedthe sheath of eyeball (or capsule of Tendon).ThisThe superior oblique arises from the common fi-sheath envelops the eyeball but is deficient in frontbrous ring, runs forwards along the upper part of theover the cornea.It is separated from the eyeball bymedial orbital wall, then it ends in a slender tendonthe episcleral space.the space contains some delicate,which enters the trochlea formed by a ligamentoussoft areolar tissue which allows the eyeball to rotatering which is attached to the upper margin of the orbitfreelyinside the sheath.and turns posterolaterally to pass between the supe-The extra ocular muscles pierces the sheath ofrior rectus and the eyeball, and is inserted into theeyeball at the equator of the eyeball, and receives asuperior surface of the sclera behind the equator ofcovering sleeve from the sheath of eyeball, whichthe eyeball. Contraction of this muscle turns the an-fades out posteriorly in continuity with the epimysi-terior pole of the eyeball inferolatarally.The inferiorum.oblique arises from thefloorof theorbit justlateral toSection 3 Blood Ves-the opening of nasolacrimal canal, and passes lateral-ly and backwards and is inserted into lateral surfacesels and Nerves of Eyeof the sclera behind the equator. Its action is to turnthe eyeball superolaterally.I.Arteries of Eye3.Levatorpalpebrae superiormuscleThe eye is supplied by the ophthalmic artery(Fig.IV-1-10).It arises from the internal carotid ar-It is a thin, triangular shaped muscle. It arisestery inside the cranial cavity and enters the orbitalfrom the inferior surface of the lesser wing of thecavity through the optic canal.sphenoid bone near the optic canal, its wide Apo-At first it lies below the optic nerve,then windsneurosis inserts into the skin and the superior tarsusround the lateral side of the nerve, crosses above ittomuscle and the upper lid, it can elevate the superiorreach themedial wall of the orbit, and runs forwardseyelid.below the superior oblique,and ends by dividingThe movement of the eyeball results from theinto the supratrochlear and dorsal nasal arteries.Itscooperation of the extra ocular muscles of both eyes.branchesareasfollows:Forexample, when two eyes arelooking upwards, thesuperior rectus and the inferior oblique muscle of twoeyes must contract simultaneously;whentwo eyes are.Central artery of retinalooking to theright side, thelateral rectus ofthe righteye and medial rectus of the left eye must contractIt isthefirst andmost importantbranch ofthesimultaneously and their opponent muscles must beophthalmic artery (Fig.V-1-5,10).It pierces therelaxed atthe same time.inferior surface of the optic nerve about 1.0-1.5cmbehind eyeball,and runsforwards to theoptic disc ofthe retina along the center of the optic nerve. In theV.Connective Tissue in theoptic disc,itdivides into superiorand inferiorbranch-Orbites, each of these divides into a large temporal anda smaller nasal arteriole,which run on the internalThe orbital cavity contains a lot of fat tissues,surface of the retina to the ora serrata, and supply thenamed the adipose body of orbit. It fills the spaceinternal lamina of the retina.The branches of the cen-around the organs within the orbit (Fig. IV-1-1),tral artery of retina can be seen through the pupil byand plays a supporting and protective role for thesethe ophthalmoscopy.If this arteryoccluded,blindnessorgans. At the anterior margin of the orbit, the adi-of the eyeresults.扫描全能王创建