The Sensory Organs

Muh.Iqbal BasriAnatomy DepartmentHasanuddin University*

The Sensory Organs

Sensory organs include the receptors and accessory organs. The receptors may be divided into three kinds: The exteroceptors : receive stimuli such as touch, temperature, pain, light and sound from the external environmentThe interoceptors : pick up information about internal environment The proprioceptors : receive stimuli from muscles, tendons, joints and ligaments*

The Visual Organ

Composition: eyeball and accessory organs of eyeShape of eyeballHas anterior and posterior polesEquator : an imaginary line encircling the eyeball, midway between anterior and posterior polesAxis of eyeball : a line joining the two polesOptic axis : a line joining the center of the pupil to the fovea centralis *

Walls of eyeballFibrous tunica of eyeballCorneaScleraVascular tunica of eyeballIrisCilliary body

Choroid

RetinaPars iridica retinaePars ciliaris retinaePars optica retinaePars caeca retinae*

Fibrous tunic of eyeball (outer)

Cornea : anterior 1/6, a nonvascular, transparent portion, richly supplied by nerves; because it is curved, the cornea helps focus lightSclera white of eye, opaque portion): posterior 5/6, consisting of fibrous connective tissue that forms a tough protective covering for eyeball, Contains sinus venosus sclerae which lies beneath the junction of cornea and sclera*

Vascular tunic of eyeball (middle)IrisThin contractile membrane anterior to ciliary body, with a central opening, the pupilContains sphincter pupillae (circular fibers) and dilator pupillae (radial fibers)Cornea and iris meet to form the iridocorneal angle*

Cilliary bodyBody a ring-shaped thickening anterior to equator, containing smooth muscle fibers called ciliary muscleCiliary processes : a series of some 60~80 projections producing aqueous humorCiliary ring*

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ChoroidThin, highly vascular in posterior 2/3 of eyeContains brown pigmented cells and dense capillary plexus

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RetinaPars caeca retinaePars iridica retinaePars ciliaris retinaePars optica retinaeLines the choroidsComposed of two layersAn outer pigment cell layer Inner neural layer (four layers)*

The fourth layer consists photoreceptor cellsCone cells are color receptors that function best during the dayRod cells are dark-light receptors that function best at night and in dim lightThe third layer consists of bipolar neuronsThe second layer is formed ganglion cells ,whose axons form optic nerveThe first layer consists of nerve axons that collect at the optic disk and pass through the sclera to form the optic nerve*

Optic disc (blind spot), located medial to posterior pole of eye, and consists of optic nerve fibers and central artery of retina Macula luteaLies lateral about 3.5 mm to optic disc, a shallow depression, it is completely free of blood vessels and is yellowish in color Fovea centralis, area of greatest visual acuity (concentration of cones), at its center The pigmentted layer absorbs light that passes completely through the anterior layer, preventing backscatter (blurring of vision)*

Contents of eyeballAqueous humorLensVitreous body*

Aqueous humor

Chamber of eye lies between cornea and lens, and divided by iris into anterior and posterior chambersAqueous humorA clear watery fluid that fills chamber of eyeContinuously secreted by ciliary body into posterior chamberPasses through pupil into anterior chamberThen it filters though iridocorneal angle into sinus venosus sclerae, this sinus drains via anterior ciliary veins into ophthalmic veins *

Ciliary body Posterior chamber Anterior chamber Sinus venosus sclera Anterior ciliary vein Ophthalmic vein Production and circulation of aqueous humor FunctionsHelps focus lightHelps maintain constant pressure in eyeballHelps nourish the lens and cornea*

LensTransparent biconvex structure, covered by an elastic transparent capsuleLocated between iris and vitreous body, and suspended behind pupil by ciliary zonuleShape changed by the ciliary muscle: for near vision, the ciliary muscle contracts and the lens rounds up, while for distant vision the lens flattens out, so that the eye may be focused on distant objects*

Vitreous bodyConsists of colorless, transparent jelly-like substance in which there is a meshwork of fine fibrils, occupies the vitreous chamber, the space between lens and retinaHelps maintain the shape of eyeball and supports the retina *

Refractive media of eyeBend entering light waves and focus them on the retina Cornea Aqueous humorLens Vitreous body*

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Accessory organs of eyeEyelidsConjunctivaLacrimal apparatus Ocular musclesConnective tissue in the orbit*

Eyelidsfrom without inwards Skin, extremely thinSubcutaneous areola tissue, loose and delicateMuscular layer: orbicularis oculiTarsus, formed by dense connective tissue in which the tarsal glands embedded Lined by palpebral conjunctivaFunction: to protect, open, and close eye*

Tarsus*

ConjunctivaThree partsPalpebral conjunctiva lining inner surface of eyelidsBulbar conjunctiva : lining anterior part of sclera, up to corneal marginConjuntival fornix (superior and inferior): line of reflection of bulbar and palpebral conjunctivaConjunctival sac*

Lacrimal apparatus Lacrimal glandOval 2-cm, occupies fossa for lacrimal glandDucts (6~10 in number): empty into anterior region of superior fornix of conjunctivaSecrets tears, which move across eyeball to medial angle,protect and moisten eye*

Lacrimal passagesLacrimal puncta opening to lacrimal ductules, one on each eylid margin near medial angle Lacrimal ductules : one in each lid, pass medially, join and enter lacrimal sacLacrimal sac within fossa for lacrimal sac, opening into nasolacrimal ductNasolacrimal duct courses 2 cm inferiorly and opens into inferior nasal meatus*

Tear is produced by lacrimal glandPasses through superior conjunctival fornix into conjunctival sacThen it is drained through lacrimal punctum, lacrimal ductule, lacrimal sac and nasolacrimal duct into inferior nasal meatus.

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Ocular muscles*

Muscle Action Nerve supplylevator palpebrae superiorisRaises upper eyelidSuperior rectusTurns eyeball superomediallyInferior rectusTurns eyeball inferomediallyMedial rectusTurns eyeball mediallyLateral retusTurns eyeball laterallySuperior obliquusTurns eyeball inferolaterallyInferior obliquusTurns eyeball superolaterally

Ocular muscles*

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Connective tissue in the orbit

Sheath of eyeball : a thin membrane, which surrounds the eyeball from optic nerve to corneoscleral junction, permits the eyeball to move in the orbit without frictionAdipose body of orbit : lies between sheath of eyeball and the orbit acts as a protective cushion and shock sorber for the eyeball*

Vessels of eye

Ophthalmic arteryBranch of internal arteryBranchescentral artery of retinaEnters optic nerve, passes toward the optic disk and then fans out to supply the retina*

Four branches: superior and inferior nasal or temporal arteriole of retina

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Ophthalmic veinSuperior ophthalmic vein communicates with facial vein anteriorly, exits posteriorly via superior orbital fissure to drain into cavernous sinusInferior ophthalmic vein lies on floor of orbit and communicates with pterygoid plexus, exits via superior orbital fissure to drain into cavernous sinus*

N. II = N. OPTICUSenter: Canalis Opticus Foramen OpticumSp. Subarach: pada Cisterna ChiasmatisNucleus: khusus noPathway:Axon sel ganglion N. OPTICUS CHIASMA OPTICUM (pada Retina) (serabut nasal + temporal) (Nasal silang, temporal tidak)CORPUS GENICULATUM LAT TRACTUS OPTICUSMETATHALAMUS (ganti Neuron)

Radiatio Opticum Cortex Occipitas Colliculus Sup (MES) Nucleus Pretectatis (MES) (Area Brodmann 17, (ganti Neuron) (ganti Neuron) Cortex Visualis PRIMER) area Brodmann 18 + 19 Tractus tectospinalis + Nucleus EW N. III (MES) (Cortex Visualis SECUNDER) Tractus tectobulbaris (ganti Neuron)Ggl Ciliare (ganti Neuron) M. Sphincter pupillae + M. Ciliare

Ggl. Sensoris: noGgl. Parasympathis: no*PENGLIHATANReflex GerakanOculi + Kepala/LeherMIOSIS PUPILLAEReflex Cahaya

Visual pathway

Optic nerveOptic chiasma Optic radiation Lateral geniculate body Visual area Optic tract *

Optic nerveOptic chiasmaOptic tractLateral geniculate bodyOptic radiationVisual area*

Pupillary reflexes

Pretectal area Accessory oculomotor nuclei Occculomotor n.Ciliary ganglia Sphincter pupilCiliary muscle *

The Vestibulocochlear Organ

Muh.Iqbal Basri*

General features

Three partsExternal ear : collects sound wavesMiddle ear : transmits sound wavesInternal ear : contains the vestibulocochlear organ concerned with equilibration and hearing*

External earAuricleExternal acoustic meatusTympanic membrane

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Auricle

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External acoustic meatusA slender canal that extends from external acoustic pore to tympanic membrane Two partsCartilaginous part lateral 1/3 Bony partmedial 2/3Lined by a layer of thin skin. This S-shaped passage medially, at first forward and upward, then backward and, finally forward and downward. *

Tympanic membrane

A thin oval membrane Two partsFlaccid part : upper 1/4Tense part : lower 3/4Umbo of tympanic membraneCone of light*

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Middle ear

Tympanic cavityAuditory tubeMastoid antrum and mastoid cells

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Tympanic cavityAn air-containing cavity locates within petrous portion of temporal bone*

Walls

RoofFloorlateral wallMedial wallPosterior wall

Anterior wall

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WallsRoof or tegmental wall formed by tegmen tympani, separates tympanic cavity from middle cranial fossaFloor or jugular wall separates the cavity from superior bulb of internal jugular veinAnterior wall or carotid wall separates tympanic cavity from carotid canal, superiorly lies two openings: Upper opening for tensor tympani muscleLower opening for auditory tube, which communicates with nasopharynx

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Posterior wall or mastoid wallAditus of mastoid antrumPyramidlateral wall or membranous wall tympanic membrane with epitympanic recess superiorly*

Medial wall or labyrinthine wallPromontoryFenestra vestibuli (oval window)Fenestra cochleae (round window) covered by secondary tympanic membraneProminence of facial canal

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Acute otitis media Perforation, inflammation ortrauma*

Auditory ossiclesConsists of chain of three bones: MalleusIncusStapesArticulate by synovial jointsTransmit vibration of tympanic membrane to footplate of stapes in fenestra vestibule.Muscles of auditory ossicles Tensor tympaniStapedius*

Auditory tubeAbout 3~4 cm long, extends from nasopharynx posteriorly, laterally, and upward to tympanic cavityTwo partsBony part: posterolateral 1/3Cartilaginous part: medial 2/3 Functions to equalize air pressure on either side of tympanic membraneIn childhood, it is shorter, wider and more horizontal than in adult*

Mastoid antrum and mastoid cells

Mastoid antrum: a small chamber between tympanic cavity and mastoid cellsMastoid cells: contain a group of air cells within mastoid process of temporal bone*

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Internal ear

General featuresLies within the petrous portion of temporal boneKey contents of internal earBony labyrinth contains perilymph Membranous labyrinth is filled with endolymph and contains the sensory organs*

Bony labyrinth

CochleaVestibuleBony semicircular canals*

CochleaIt somewhat resembles a snails shellConsists of ModiolusCochlear spiral canal makes two and one-half spinal turns around the modiolus Osseous spiral laminaScala vestibuliScala tympani*

VestibuleHollow bony spaceContains utricle and saccule*sacculusutriculusampulla

Semicircular duct in eachCanal at right angles to each otherDilated ampulla in each canalcalled bony ampullar

Bony semicircular canals(anterior, posterior, and lateral) posteriorly

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Membranous labyrinth

Cochlear ductUtricle and sacculeSemicircular ducts

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Cochlear ductContains spinal organ (of Corti), the sound receptors lies on tympanic wall of cochlear duct*

Utricle and sacculeContain macular utricli and macular sacculi, end organs of balance, which respond to linear acceleration and deceleration, static of gravity*

Semicircular ductsEach duct has a membranous ampullaeContaining crista ampullaris, receptors of balance that respond to rotational acceleration in three different planes

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Conduction of soundAir-conduction of sound Sound wavesCochlear nerve*

Bony- conduction of soundSound waves Skull Bony labyrinth Perilymph Endolymph within cochlear duct Spinal organCochlear nerve*

Internal acoustic meatusExtends from internal acoustic pore to fundus of internal acoustic meatusFacial, vestibulocochlear nerves and vessles of labyrinth pass through the fundus of internal acoustic meatus*

N. VIII = N. VESTIBULARIS 1enter: dari Labyrinthus Ossis Temporalis MAI PAI (bersama N. Cochlearis)

Sp. Subarach: Cisterna Basalis + Cisterna Pontis

Nucleus: Nuclei Vestibulares td. Lateralis, Medialis, Sup and Inf (SK)

Pathway:

Organa VestibularisGgl. VestibulareN. Vestibularis (Sacculus, Utriculus, (dalam MAI)Ductus Semicircularis)

Nuclei Vestibulares(Via MAI/PAI)

PCI Tractus FLM Nucleus VP ThalamusVestibula Sp. (pd TC) Cerebellum Radiatio Thalami Med. SpNucleus N. III, IV, VI Cortex Gyrus post centralis area Vestibularis Primer (= area Brodmann 3, 1, 2)

Cortex Vestibularis Secunder (?)

Ggl. Sensoris: Ggl. Vestibulare (SK)

Ggl. Parasympathis: no*

N. VIII = N. COCHLEARIS 2enter: dari Labyrinthus Ossis Temporalis MAI PAI (bersama N. Vestibularis)

Sp. Subarach: Cisterna Basalis + Cisterna Pontis

Nucleus: Nuclei Cochlearis Ventralis/Ant + Dorsalis/Post (SK)

Pathway:

Organa Spirale Corti Ggl. Spirale N. Cochlearis(dlm Canalis Spiralis) (ganti Neuron)

Stria acustica

ascendens sbgNucleus Corpus Trapezoideum +Lemniscus Lat Nucleus Olivarius Superior, Bilateral (ganti Neuron)

Corpus Geniculatum MedialeColliculus Inf Metathalamus(ganti Neuron) (ganti Neuron)Colliculus Inf Radiatio Acustica Kontralat Gyrus Temporalis Transv C. G. Lat sepihak (Cortex Auditoria Primer) = area Brodmann 41

Cortex Auditoria Secunder = area Brodmann 42 + 22

Ggl. Sensoris: Ggl. Cochlearis (SK)

Ggl. Parasympathis: no*

Auditory pathwayBipolar neuron of cochlear ganglion Cochlear nerveCochlear nucleiTrapezoid body Lateral lemniscus Medial geniculate body Acoustic radiation Transverse temporal gyrus*

Olfactory system*

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N.OlfactoriusArise from olfactory nerve cells, above superior chonchaBundles of these nerves openings in the lamina cribrosa ossis ethmoidalisBulbus olfactoriusTractus olfactoriusOlfactory area of cerebral cortex*

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Olfactorius Pathway*

N. I = N. OLFACTORIUSenter: Lamina Cribrosa Os EthmoidaleSp. Subarach: anterior Cisterna ChiasmatisNucleus: noPathway:Fila Olfactoria Bulbus Olfactorius Tractus Olfatorius(pd mucosa cav. Nasi) (ganti neuron) (ke subst. perforata ant) stria olfactoria St. Olf. Lateralis St. Olf. Intermedia St. Olf. Medialis (paling besar/penting) Cortex Subst. Perf. Ant ke bulbus olf. Kontralat area periamygdalae + (area olf. Primer) + sistem Limbik + prepiriformis (uncus) area Brodmann 25 (cortex olf. PRIMER) (cortex olf. PRIMER) Area Entorrhinal(pd gyrus parahippocampi) = Area Olfactoris SECUNDER (area Brodmann 28)Ggl. Sensoris + Parasympathis: no*penciuman

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Gustatory System*

MusclesIntrinsic : The longitudinal, transverse and vertical musclesExtrinsic : The genioglossus, hyoglossus, styloglossus and palatoglossus muscles*

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Mucous membraneSulcus terminalis v-shaped groove, upper surface of the tongueType of papillae: Papilla filiformis Papilla fungiformis Papilla vallatae 10-12 in number *

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Blood SupplyArteri lingualis Ramus tonsilaris a. FacialisA. Pharyngea ascendens*

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Clinical NotesLaceration of The Tongue : Bleeding is halted by grasping the tongue between the finger and thumb posterior to the laceration, thus occluding the branches of the lingual artery.*

Lymph drainageTip : submental lymph nodesSides of anterior two thirds : submandibular lymph nodesPosterior third : deep cervical lymph nodes*

Sensory and Motoric InnervationAnterior two thirds : the lingual nerve (general sensation) and chorda tympani (taste)Posterior two thirds : the glossopharyngeal nerve (general sensation and taste)Motoric : n.hypoglossus*

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Chorda tympani*

Movement of the tongueProtrusion: m.genioglossus (both sides)Retraction : m.styloglossus and m.hyoglossus (both sides)Depression : m.hyoglossus (both sides)Retraction and elevation of posterior third m.styloglossus and m. Palatoglossus (both sides)Shape changes: intrinsic muscles*

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Gustatory Pathway*

N. VII = N. FACIALIS (+ N. Intermedius) 1enter/exit: Meatus Acusticus Internus Canalis Facialis For. Stylomastoideum

Sp. Subarach: Cisterna Basalis + Cisterna Pontis

Nucleus: 1. Nucleus Motoris N. VII (BM) 2. Nucleus Salivatorius Sup (VM) 3. Nucleus Tractus Solitarius (SK) 4. Nucleus Tractus Spinalis N. V (SU)

Pathway:SENSORIS UMUM (kulit area MAE and proprioseptif mm. faciales)

Rm. Auricularis N. X N. VII ggl. geniculatum Nucleus tract. Spinalis N. V (dlm genu can. Facialis)

SENSORIS KHUSUS (taste 2/3 ant. Lingua)

chorda tympaniN. VIIggl. GeniculatumN. Intermedius(dlm N. Lingualis N. V3)

ascendens kesilang kontralatNucleus Tractus SolitariusNucleus VPM Thalamus

Radiatio ThalamiOperculum frontopariataleCortex Gustatoris Secunder (area gustatoris Primer) (Lobus Insulae???) = area Brodmann 43*Selanjunyat idem SENSORIS N. VBtk N. Intermedius

N. VII = N. FACIALIS (+ N. Intermedius) 2Pathway (cont.):VISCEROMOTORIS (motoris parasympathis untuk kelenjar2 mucosa cav. nasi, cav. oris, sinus paranasalis, labia & gld. Lacrimalis, gld. Submandibularis, gld. sublingualis)

Nucleus Salivarius SupN. IntermediusGgl. Geniculatum N. VII

Ikut cabang-cabang N. V1, V2, V3Ggl. PterygopalatinumN. Petrosus Superf. (ganti Neuron) major N. VIIGld. Lacrimalis, Nasales, Labiales,Palatinae, Buccales, ParanasalesGgl. Submandibulareikut N. Lingualis N. V3 Chorda Tympani

Gld. SubmadibularisGld. Sublingualis*

N. VII = N. FACIALIS (+ N. Intermedius) 3Pathway (cont.):BRANCHIOMOTORIS (mm. faciales, m. stylohyoideus, m. digast. V. Post)

Nucleus Motoris N. VII N. VII Ggl. Geniculatum N. VII

Ggl. Sensoris: Ggl. Geniculatum (SU + SK)

Ggl. Parasympathis: 1. Ggl. Pterygopalatinum 2. Ggl. Submandibulare*

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Thank you*

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