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