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Sense OrgansSense Organs
1.1. Sense organs Sense organs –– classification classification 2.2. Sensory receptorsSensory receptors3.3. Gustatory apparatusGustatory apparatus4.4. Olfactory apparatusOlfactory apparatus5.5. Visual apparatus Visual apparatus –– the eye. Visual pathwaythe eye. Visual pathway6.6. Vestibulocochlear apparatus Vestibulocochlear apparatus –– the ear. the ear.
Auditory and vestibular pathwaysAuditory and vestibular pathways
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 2
�� ff ive senses:ive senses:�� touchtouch�� tastetaste�� smellsmell�� ssightight�� hearinghearing
�� specialized cells specialized cells –– receptors for specific stimulireceptors for specific stimuli:� confined to the head region� receptors are not free endings of sensory neurons
Human sense organsHuman sense organsSense organsSense organs
Five Senses IconsFive Senses IconsFive Senses IconsFive Senses IconsFive Senses IconsFive Senses IconsFive Senses IconsFive Senses Icons
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 3
Sense of touchSense of touchSense organsSense organs
�� four kinds of touch sensationsfour kinds of touch sensations ::�� light tlight t ouchouch (contact)(contact)
�� coldcold
�� heatheat
�� painpain
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 4
�� 3 main groups 3 main groups –– Sherrington, 1906Sherrington, 1906::
�� exteroceptorsexteroceptors
�� proprioceptorsproprioceptors
�� interoceptorsinteroceptors
�� by sensory modality:by sensory modality:
�� baroreceptorsbaroreceptors – respond to pressure
�� chemoreceptorschemoreceptors – chemical stimuli
�� mechanoreceptorsmechanoreceptors – mechanical stress
�� nociceptorsnociceptors – pain perception
�� thermoreceptorsthermoreceptors – temperature (heat, cold or both)
�� by location:by location:
�� cutaneous receptorscutaneous receptors
�� muscle spindlesmuscle spindles
�� by morphologyby morphology:
�� free nerve endingsfree nerve endings
�� encapsulated receptorsencapsulated receptors
Sensory receptors Sensory receptors –– classification classification Sense organsSense organs
C.S. SherringtonC.S. Sherrington18571857––19521952
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 5
Gustatory apparatusGustatory apparatusSense organsSense organs
NB:NB: about 50 fibers innervate a single taste bud!about 50 fibers innervate a single taste bud!
�� peripheral gustatory organsperipheral gustatory organs ::
�� taste buds taste buds
(gustatory caliculi(gustatory caliculi) ) –– 20002000--9000:9000:
�� vallate papillae vallate papillae –– most numerousmost numerous
� plentiful in the posterior posterior ⅓⅓ of the tongueof the tongue
�� fungiform papillaefungiform papillae
�� soft palate, epiglottis and pharynxsoft palate, epiglottis and pharynx
�� nono structuralstructural differencedifference amongamong tastetaste buds:buds:�� gustatory (taste) poregustatory (taste) pore – 2-3 µm� collection of 5050--100 epithelial cells100 epithelial cells� contain long microvillimicrovilli
extend through a taste pore� contain two types of
gustatory receptor cellsgustatory receptor cells• with and without dense-cored granules
�� supportingsupporting (non-sensory) cellscells�� basal cellsbasal cells – undifferentiated,
form new receptor cells every 10-14 days
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 6
Gustatory apparatusGustatory apparatusSense organsSense organs
NB:NB: about 50 fibers innervate a single taste bud!about 50 fibers innervate a single taste bud!
�� traditionally four basic qualities traditionally four basic qualities of taste:of taste:�� sweetnesssweetness�� bitternessbitterness�� sournesssourness�� saltinesssaltiness
�� fifth basic tastefifth basic taste�� umamiumami (“deliciousnessdeliciousness”) –
non-salty sensations evoked by some amino acids – glutamate
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 7
�� the sense of smell (olfaction):the sense of smell (olfaction):� receptors are part of the olfactory epithelium
�� olfactory mucosa olfactory mucosa – 3 cell types:� cell bodies of olfactory receptor cellsolfactory receptor cells
(40 million in human olfactory epithelium)
�� supporting cellssupporting cells – columnar cells
�� basal cellsbasal cells – form new receptor neurons (4-8 weeks)
�� olfactory (Bowmanolfactory (Bowman’’s) glandss) glands –– in lamina propriain lamina propria
Olfactory apparatusOlfactory apparatusSense organsSense organs
NB:NB: The smell receptors are sensitive toThe smell receptors are sensitive toThe smell receptors are sensitive toThe smell receptors are sensitive toThe smell receptors are sensitive toThe smell receptors are sensitive toThe smell receptors are sensitive toThe smell receptors are sensitive to seven types of sensationseven types of sensationseven types of sensationseven types of sensationseven types of sensationseven types of sensationseven types of sensationseven types of sensation::
camphor, musk, flower, mint, ether, acrid, or putrid!camphor, musk, flower, mint, ether, acrid, or putrid!
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 8
Olfactory neuroepitheliumOlfactory neuroepithelium� non-myelinated axons of the
olfactory epithelium:� gather into 18-20 bundles –
filaments of the olfactory nerve (CNI)� pass through the cribriform plate of the
ethmoid bone � attach to the olfactory bulbs
Sense organsSense organs
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 9
Olfactory bulbOlfactory bulbSense organsSense organs
� transmits smell information from the nose to the brain:� supported and protected by the cribriform plate
� multi-layered cellular architecture:� glomerular layer� external plexiform layer � mitral cell layer � internal plexiform layer � granule cell layer
� olfactory bulb – synaptic glomeruli:� nucleus of termination of cranial nerve I� mitral, granule and periglomerular cells� initial part of rhinencephalon
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 10
Olfactory tractOlfactory tract� consists of:
� axons of the mitral and tufted cells� centrifugal axons from the opposite bulb
� anterior olfactory nucleusanterior olfactory nucleus:� medium-sized multipolar neurons� their axons continue into the olfactory
striae and trigone�� olfactory striaeolfactory striae:
� lateral olfactory stria � limen insulae� medial olfactory stria � diagonal band of Broca
�� anterior perforate substanceanterior perforate substance�� olfactory tubercleolfactory tubercle – reduced in man
Sense organsSense organs
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 11
�� primary olfactory cortexprimary olfactory cortex:�� prepiriform cortex prepiriform cortex –– lateral olfactory gyrus lateral olfactory gyrus �� gyrus ambiensgyrus ambiens
�� periamygdaloidperiamygdaloid areaarea –– laterallateral olfactoryolfactory striastria �� gyrus semilunarisgyrus semilunaris
�� secondary olfactory cortexsecondary olfactory cortex:�� entorhinal areaentorhinal area, cranial part of parahippocampal gyrus
Olfactory cortex (piriform lobe)Olfactory cortex (piriform lobe)Sense organsSense organs
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 12
�� The eye The eye –– ssome amazing facts:ome amazing facts:� the eyeballeyeball of a human weighsweighs approximately 28 g28 g;;
� although only 1/6th of it is exposed to the outside world, about half of our brain is involved in the seeing process – hhumans areumans are thus very much visual animalsvisual animals!
� the only part of our body that can function at 100%can function at 100%ability at any moment, day or night, without restwithout rest;;
�� most complex organs most complex organs wewe possesspossess – composed of more than 2 million working partsmore than 2 million working parts;;
� the external muscles that move the eyes are the strongest muscles in the human body for the jobstrongest muscles in the human body for the job that they have to do. They are 100 times more powerful than they need to be!
� the retina contains 120 million rods for "night visionnight vision", and 8 million cones that are colour sensitivecolour sensitive and work best under daylight conditionsdaylight conditions;;
� contributes towards 85% of 85% of ourour total knowledgetotal knowledge –can process 36,000 bits of information every hour.
Human visual organsHuman visual organs
NB: NB: Human eye:Human eye:Human eye:Human eye:Human eye:Human eye:Human eye:Human eye: a window to the outside worlda window to the outside worlda window to the outside worlda window to the outside worlda window to the outside worlda window to the outside worlda window to the outside worlda window to the outside world!!
Human eyeHuman eye
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 13
�� The eye The eye –– Lat. Lat. oculusoculus, Gr. , Gr. ophthalmosophthalmos::�� eyeball eyeball –– coatscoats
�� ocular fibrous tunicocular fibrous tunic•• sclerasclera•• corneacornea
�� vascular tunic (uveal tract)vascular tunic (uveal tract)•• choroid choroid •• ciliary bodyciliary body•• irisiris
�� retinaretina
�� ocular refractive mediaocular refractive media�� aqueous chamber&humoraqueous chamber&humor�� vitreous bodyvitreous body�� lenslens
�� accessory structuresaccessory structures� extraocular muscles� eyebrows and eyelids� lacrimal apparatus
Anatomy of the eyeAnatomy of the eyeHuman eyeHuman eye
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 14
Human eyeHuman eye
EyeballEyeball�� Eyeball Eyeball –– the peripheral organ of sightthe peripheral organ of sight ::
� embedded in the fat of the orbitorbit� enveloped by a fascial sheath (capsule of capsule of TenonTenon)�� anterior and posterior polesanterior and posterior poles � optic (visual) axisoptic (visual) axis� approximately spherical spherical ““ballball”” – dimensions:
� vertical diameter – 23.5 mm� anterioposterior diameter – 24 mm (17.5 mm at birth)
� three coatscoats (tunics):�� fibrous tunicfibrous tunic�� vascular, pigmented tunicvascular, pigmented tunic�� nervous layer, retinanervous layer, retina
� content – ocular refractive mediaocular refractive media
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 15
Human eyeHuman eye
Ocular fibrous tunicOcular fibrous tunic�� Sclera (tunica sclera) Sclera (tunica sclera) –– Gr. Gr. sklerosskleros, hard:, hard:
� the outer layer of the eyeball – ““the white of the eyethe white of the eye””� the posterior fiveposterior five--sixthssixths
of the connective tissue coat of the globe
� firm protective membraneprotective membrane �
maintains the shape of the globe �� smooth, smooth, provides an attachment
for the extraocular muscle insertions �� perforated by many nerves and vesselsperforated by many nerves and vessels
�� lamina cribrosa, sinus venosus scleraelamina cribrosa, sinus venosus sclerae (canal of Schlemm)
�� opaqueopaque with varying varying thicknessthickness::� 1 mm at the posterior pole� 0.3 mm just behind muscle insertions
�� fibrous connective tissue fibrous connective tissue – four layers:�� episcleraepisclera�� stromastroma�� lamina fuscalamina fusca�� endotheliumendothelium
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 16
Human eyeHuman eye
Ocular fibrous tunicOcular fibrous tunic�� Cornea Cornea –– ““keratkerat--““, Gr., Gr. κέραςκέρας, horn, horn
�� projecting and transparent front partprojecting and transparent front part of the eye � refracts (together with the lens) light (~ 43 dioptres)
� the anterioranterior oneone--sixthssixthsof the connective tissue coat of the globe
�� densedense with varying varying thicknessthickness::� ~1.2 mm round its periphery� 0.5-0.6 mm at its centre
�� nonnon--vascular structure vascular structure � surface ectodermal origin
�� richly innervated richly innervated �� corneal (blink) reflexcorneal (blink) reflex
�� structurally structurally – five layers:
� corneal epitheliumepithelium� anterior limiting membrane (of BowmanBowman)
� substantia propria (corneal stromastroma )
� posterior limiting membrane (of DescemetDescemet)
�� endotheliumendothelium of the anterior chamber
NB:NB: The mnemonic "The mnemonic "EBSDEEBSDEin", read as "in", read as "EbsteinEbstein" "
can be used to remember the layers in sequencecan be used to remember the layers in sequence!!
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 17
Human eyeHuman eye
Vascular tunic (uveal tract)Vascular tunic (uveal tract)�� Choroid Choroid –– ⅔⅔ of the uveal tract surface of the uveal tract surface ~ 0.5 mm in humans::
� thin, highly vascular coatvascular coat, dark brown or chocolate
�� dense capillary plexusdense capillary plexus – provides oxygen and nourishment to the outer layers of the retina
� composition:�� suprachoroid laminasuprachoroid lamina – ~ 30 µm thick� choroid proper:
•• vascular laminavascular lamina•• capillary lamina (choroidocapillaris)capillary lamina (choroidocapillaris)•• basal lamina (membrane of basal lamina (membrane of BruchBruch))
NB:NB:NB:NB:NB:NB:NB:NB: uva, Lat. grapeuva, Lat. grapeuva, Lat. grapeuva, Lat. grapeuva, Lat. grapeuva, Lat. grapeuva, Lat. grapeuva, Lat. grape
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 18
Human eyeHuman eye
Vascular tunic (uveal tract)Vascular tunic (uveal tract)�� Ciliary bodyCiliary body –– Lat. Lat. ciliumcilium, eyelid:, eyelid:
�� the circumferential tissue inside the the circumferential tissue inside the eyeeye�� triangular in horizontal sectiontriangular in horizontal section� coated by a double layer, the ciliary epitheliumciliary epithelium
� superficial lamina – columnar cells� deep layer – cuboidal cells with pigment granules
� composition:�� ciliary ring, ciliary ring, orbiculus ciliarisorbiculus ciliaris (pars plana) – 3.5-4 mm�� corona ciliariscorona ciliaris (pars plicata)
•• 70-80 ciliary processes ciliary processes � aqueous humor•• ciliary plicaeciliary plicae
�� ciliary muscleciliary muscle � zonule of Zinn � lens (suspensory ligament)•• meridional (muscle of meridional (muscle of BrBrüückecke))•• radial (oblique) fibersradial (oblique) fibers•• circular (muscle of circular (muscle of MMüüllerller))
�� functions:functions:�� aaccommodationccommodation�� aqueousaqueous humorhumor productionproduction �� glaucomaglaucoma�� production and maintenance production and maintenance
of the lens zonulesof the lens zonules
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 19
Human eyeHuman eye
Vascular tunic (uveal tract)Vascular tunic (uveal tract)�� Iris Iris –– GreekGreek goddess of the rainbowgoddess of the rainbow::
�� opaque, pigmented diaphragmopaque, pigmented diaphragm�� two major regionstwo major regions:
�� pupillary zonepupillary zone �� pupilpupil•• a a sphincter sphincter muscle (muscle (sphincter pupillaesphincter pupillae))•• a set of dilator muscles (a set of dilator muscles (dilator pupillaedilator pupillae))
�� ciliary zoneciliary zone � ciliary body
� iridocorneal angle � FontanaFontana’’s spacess spaces� microscopic structure:
� pigmented fibrovascular tissue (stromastroma)� pigmented epithelial cells
�� functions:functions:�� ccontrolontrol ofof the diameter and size of the the diameter and size of the pupilpupil�� the amount of light reaching the the amount of light reaching the retinaretina�� responsibleresponsible for for
the the ““eeye color"ye color"
Iris eyeIris eyeIris eyeIris eyeIris eyeIris eyeIris eyeIris eye recognitionrecognition
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 20
Human eyeHuman eye
RetinaRetina�� Retina Retina –– Lat.Lat. rete, rete, net:net:
�� aapprpproxox.. 72%72% ofof thethe eyeballeyeball internalinternal surfacesurface�� neuronal,neuronal, lightlight--sensitivesensitive layerlayer of the eyeball�� two principal parts two principal parts –– ora serrata:ora serrata:
� anterior ““blindblind”” partpart•• ciliary partciliary part•• iridial partiridial part
� posterior optic partoptic part•• macula luteamacula lutea �� fovea centralisfovea centralis•• optic disc optic disc –– ““blind spotblind spot””
�� structure structure –– two major two major layerslayers:�� outer outer stratum pigmentosumstratum pigmentosum �� pigment epitheliumpigment epithelium�� inner inner stratum nervosumstratum nervosum
�� functions:functions:�� the same the same functionfunction as the film in a cameraas the film in a camera
•• recereceiives the image seen through ves the image seen through ourour eyeeye•• convertconvertss a light signal into a neural signal a light signal into a neural signal
("signal transduction")("signal transduction")•• transmits this image through the optical nervetransmits this image through the optical nerve
to the brainto the brain
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 21
Human eyeHuman eye
Structure of the retinaStructure of the retina�� three layers of three layers of retinal neuronsretinal neurons�� two layers of two layers of synapsessynapses�� retinal pigment epitheliumretinal pigment epithelium
�� 44--6 million hexagonal6 million hexagonal cells cells –– fuscinfuscin
�� neural part of retinaneural part of retina –– 5 cell types5 cell types::�� neuroepithelialneuroepithelial ((photoreceptorphotoreceptor ) ) cellscells
–– in in stratum neuroepithelialestratum neuroepitheliale��rodsrods��conescones
�� bipolar cells bipolar cells –– inin stratum ganglionare retinaestratum ganglionare retinae
�� ganglion cells ganglion cells –– inin stratum ganglionare nervi opticistratum ganglionare nervi optici
�� horizontal cells horizontal cells –– GABAergic interneurons GABAergic interneurons –– inin stratum plexiforme externum stratum plexiforme externum
�� amacrine cells amacrine cells –– inin stratum plexiforme internumstratum plexiforme internum
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 22
Human eyeHuman eye
Photoreceptor cellsPhotoreceptor cells�� neuronsneurons capablecapable ofof phototransductionphototransduction�� classicclassic photoreceptorsphotoreceptors – two main classes:
�� rods rods –– 75 to 150 million75 to 150 million�adapted for low light "night visionnight vision“�contain rhodopsinrhodopsin
�� conescones –– ~ 7~ 7 millionmillion�� function well in bright lightfunction well in bright light ““daylightdaylight””��detect colorsdetect colors –– three different typesthree different types
•• responding to short (blueblue) light• responding to medium (greengreen) light• responding to long (yellowyellow--redred) light
�� photosensitive ganglion cells photosensitive ganglion cells ––11--2% of all (1.3 million) ganglion cells in humans2% of all (1.3 million) ganglion cells in humans
� the same basic structurestructure:�� cell bodycell body with nucleus in outer nuclear layer�� outer segmentouter segment (discs), stalkstalk (cilium), inner segmentinner segment
(mitochondria) in photoreceptor layer
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 23
Human eyeHuman eye
Bipolar cellsBipolar cells�� transmit signals from the photoreceptors to the ganglion cellstransmit signals from the photoreceptors to the ganglion cells –– interneuronsinterneurons� three typestypes bipolar neurons:
�� rodrod bipolar cells� midget (cone) cells� flat bipolar cells
� common bipolar cell structurestructure:� a central cell bodycell body in inner nuclear layer�� outer processouter process
�� makes synapse with either rods or conesmakes synapse with either rods or cones�� inner processinner process
�� accepts synapses from horizontal cellsaccepts synapses from horizontal cells� direct innervationinnervation of the photoreceptor above it,
either through ametabotropicmetabotropic (ON) (ON) or or ionotropicionotropic (OFF) (OFF) receptorreceptor
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 24
Human eyeHuman eye
Ganglion cellsGanglion cells�� receive visual information from receive visual information from photoreceptorsphotoreceptors
via via bipolar bipolar and and amacrine cellsamacrine cells�� transmit visual information from retina to several regions in transmit visual information from retina to several regions in brain� ~ 1.2 to 1.5 million retinal ganglion cells in the human retina�� five main classesfive main classes of ganglion neurons:
�� midget ganglion cells midget ganglion cells –– monosynaptic; A cellsmonosynaptic; A cells�� pparasol (arasol (mmagnocellular; B cells)agnocellular; B cells)�� polysynaptic (rod and flat)polysynaptic (rod and flat) ganglion cellsganglion cells�� photosensitive ganglion cellsphotosensitive ganglion cells
�� structurestructure:� a central cell bodycell body in ganglionic cell layer�� inner processinner process
�� makes synapse with either bipolar or amacrine cellsmakes synapse with either bipolar or amacrine cells�� outer processouter process – long axon extending into the brain
� forms the optic nerveoptic nerve
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 25
Human eyeHuman eye
Macular areaMacular area�� macula lutea macula lutea ((Lat.Lat.maculamacula, "spot" + , "spot" + lutealutea, "yellow"), "yellow"):
� oval-shaped highly pigmented yellow spotyellow spotwith diameter of around 5 mm
� centre of the macula is the foveal pit, foveafovea centraliscentralis� the fovea contains the largest concentration of
cones in the eye � allows for the sharpest visionsharpest vision
�� optic disk (papilla)optic disk (papilla):� location where ganglion cell axons exit the eye
to form the form the optic nerveoptic nerve� placed 3 to 4 mm to the nasal side of the fovea� vertical oval with a central depression, opticoptic cupcup� contains no light sensitive receptor cells –
““the blind spotthe blind spot””
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 26
Human eyeHuman eye
Inverted retinaInverted retina�� ‘‘invertedinverted’’ arrangement of the vertebrate retinaarrangement of the vertebrate retina::
�� the light sensing cells sit at the back side the light sensing cells sit at the back side
of the retinaof the retina
�� light has to pass through several light has to pass through several
inner layers of its neural apparatus inner layers of its neural apparatus
before reaching the photoreceptorsbefore reaching the photoreceptors
�� aan image of the external environment n image of the external environment
is thus focused on the retina which is thus focused on the retina which
transduces light into neural signalstransduces light into neural signals
� neural impulses pass back from the photoreceptor layer through the ganlionic cell layer to the optic nerve
� opposite directions of light and nerve impulse!
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 27
Human eyeHuman eye
Ocular refractive mediaOcular refractive media�� Ocular refractive media:Ocular refractive media:
�� aqueous chambers aqueous chambers ––anterior and posterioranterior and posterior��aqueous humoraqueous humor
�� vitreous chambervitreous chamber��vitreous bodyvitreous body
�� lenslens
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 28
Human eyeHuman eye
Aqueous chambers and humorAqueous chambers and humor�� aqueous chambers:aqueous chambers:
�� anterioranterior – between the posterior surface of the cornea and the iris
�� posteriorposterior – between the iris and the front face of the vitreous body
�� aqueous humor:aqueous humor:� provides nutrients to the lens
and corneal endothelium� maintains the convex shape of the cornea� carries away waste products from metabolism
�� compositioncomposition:� water – 99%, glucose, amino acids� ions: HCO3
-; Cl-; Na+; K+; Ca2+; PO43-
� proteins: albumin, β-globulins� production and drainage:
� secreted into posterior chamber by the ciliary body� drains into Schlemm’s canal � glaucoma
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 29
Human eyeHuman eye
Vitreous chamber and bodyVitreous chamber and body�� vitreous chamber vitreous chamber –– ~4/5 of the eyeball~4/5 of the eyeball
�� the gel in vitreous chamber is stagnantthe gel in vitreous chamber is stagnant�� vitreous body:vitreous body:
�� transparent, colourless, gelatinous masstransparent, colourless, gelatinous mass�� produced by certain retinal cellsproduced by certain retinal cells
�� structure:structure:�� vitreous (hyaloid) membranevitreous (hyaloid) membrane peripherally�� hyaloid canalhyaloid canal centrally�� very few cellsvery few cells – phagocytes and hyalocytes� contains no blood vesselsno blood vessels
�� compositioncomposition:� water – 99%� some salts� little glycoprotein and hyaluronate� vitrosin (a type of collagen)
�� functionsfunctions:� refracting media� helps to keep the retina in place
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 30
Human eyeHuman eye
LensLens�� lens:lens:
�� transparent, transparent, biconvex bodybiconvex body�� structure:structure:
�� anterior and posterior polesanterior and posterior poles�� equator and capsuleequator and capsule� soft cortical substancecortical substance� firm, central part, nucleusnucleus� contains no true elastic tissueno true elastic tissue� lens fibers (cells) – superficial and deep
�� functionfunction:� helps to refract light to be focused on the retina� contributes about 15-18 dioptres (⅓)
to the total dioptric power
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 31
Human eyeHuman eye
Accessory visual apparatusAccessory visual apparatus
�� Extraocular musclesExtraocular muscles
�� Eyebrows and eyelidsEyebrows and eyelids
�� ConjunctivaConjunctiva
�� Lacrimal apparatusLacrimal apparatus
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 32
Human eyeHuman eye
Extraocular musclesExtraocular muscles
�� extraocular muscles:extraocular muscles:
�� elevator of the upper eyelidelevator of the upper eyelid
�� superior and inferior tarsal musclessuperior and inferior tarsal muscles
�� orbital muscleorbital muscle
�� fourfour rectirecti muscles – annular tendon
�� superior rectussuperior rectus
�� inferior rectusinferior rectus
�� lateral rectuslateral rectus
�� medial rectusmedial rectus
�� two obliquitwo obliqui muscles
�� obliquus superiorobliquus superior
�� obliquus inferiorobliquus inferior
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 33
Human eyeHuman eye
EyebrowsEyebrows�� eyebrows:eyebrows:
� two arched eminences of skin� numerous short, thick hairs� fibers of orbicularis oculi, corrugator and frontal
belly of occipitofrontalis muscles� functions:
� protect the eye – prevent moisture, mostly salty sweat and rain, from flowing into the eye
� important to human communication and facial expression
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 34
Human eyeHuman eye
EyelidsEyelids�� eyelids, eyelids, palpebrae:palpebrae:
� thin, movable folds that covers and protects eyes
� upper eylid is larger and more movable
� palpebral fissure
� lateral angle of the eye (lateral canthus)
� medial angle (medial canthus)
� lacus lacrimalis
� lacrimal caruncle – small, reddish, conical body
� lacrimal papilla
� punctum lacrimale
� eyelashes – short, thick curved hairs
� ciliary glands (of Moll)
� Meibomian (tarsal) glands
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 35
Human eyeHuman eye
ConjunctivaConjunctiva�� conjunctiva:conjunctiva:
� transparent mucous membrane
� consisting of cells and underlying basement membrane
� over the inner surface of the eyelids
� over the front part of the sclera and cornea
�� palpebral conjunctivapalpebral conjunctiva� highly vascular
� adherent to the tarsi
� conjunctival fornix
�� ocular conjunctivaocular conjunctiva� thin, transparent
� loosely connected to the eyelid
� continues as the corneal epithelium
�� semilunar fold of conjunctivasemilunar fold of conjunctiva
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 36
Human eyeHuman eye
Human lacrimal apparatusHuman lacrimal apparatus
�� lacrimal glandlacrimal gland
�� lacrimal canaliculilacrimal canaliculi
�� lacrimal saclacrimal sac
�� nasolacrimalnasolacrimal (tear)(tear) ductduct
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 37
Human eyeHuman eye
Lacrimal glandLacrimal gland
� almond-like, two parts two parts by the aponeurosis
of the levator palpebrae superioris muscle:
� larger upper orbital part orbital part – in fossa lacrimalis
� smaller lower palpebral partpalpebral part, ⅓ of the orbital
� small accessory lacrimal glandsaccessory lacrimal glands
� more numerous in the upper lid
� in and near the conjunctival fornices
� ~12 ducts
� into the superior conjunctival fornix
�� secretessecretes a complex fluid, the tearsthe tears
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 38
Human eyeHuman eye
Lacrimal pathwaysLacrimal pathways�� lacrimal canaliculilacrimal canaliculi –– superior and inferiorsuperior and inferior:
� ~10 mm in length� dilated into ampullaeampullae� commence at the puncta lacrimaliapuncta lacrimalia
�� lacrimal saclacrimal sac:� upper blind end of the nasolacrimal duct
� connect it with the lacrimal canaliculi� ~12 mm in length, lodged in a fossa
�� nasolacrimal (tear) duct:nasolacrimal (tear) duct:� membranous canal; ~18 mm long� drains into the inferior nasal meatus
Structure of the tear filmStructure of the tear filmObstruction of the lacrimal drainageObstruction of the lacrimal drainage
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 39
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 40
� The peripheral auditory apparatus, the earthe ear , auris, Gr. us, Gr. us, ωτοωτο == genitive genitive for earfor ear::� external (outer) earexternal (outer) ear, auris externaauris externa
�� auricle (pinna)auricle (pinna)
�� external auditory meatus (ear canal)external auditory meatus (ear canal)
�� middle earmiddle ear, auris mediaauris media�� tympanic membrane (ear drum)tympanic membrane (ear drum)
�� tympanic cavitytympanic cavity
�� auditory (Eustachian) tubeauditory (Eustachian) tube
�� auditory ossiclesauditory ossicles
�� internal (inner) earinternal (inner) ear, auris internaauris internaauditory and vestibular portionsauditory and vestibular portions:�� osseous labyrinthosseous labyrinth
�� membranous labyrinthmembranous labyrinth
Anatomy of the earAnatomy of the earHuman earHuman ear
NB: NB: HumanHumanHumanHumanHumanHumanHumanHuman ear:ear:ear:ear:ear:ear:ear:ear: the organ of hearing and balancethe organ of hearing and balancethe organ of hearing and balancethe organ of hearing and balancethe organ of hearing and balancethe organ of hearing and balancethe organ of hearing and balancethe organ of hearing and balance
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 41
External earExternal ear , , auris externaauris externa� the first structure of the sound conduction apparatus – serves to
collectcollect and conductand conduct the air vibrationsthe air vibrationsto the tympanic membrane
Human earHuman ear
�� auricle (pinna)auricle (pinna) – auriculaauricula�� external acoustic meatusexternal acoustic meatus
((ear canalear canal) ) –– meatus acusticus meatus acusticus externusexternus
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 42
Auricle,Auricle, auriculaauricula� pinna – Lat. Lat. pinnapinna, a feather, a feather:
� thin skin with fine hairs
� elastic fibrocartilagefibrocartilage� lobule of auricle� auricular tubercle
(of Darwin)�� ligaments of auricleligaments of auricle, ,
extrinsic and intrinsic,
�� auricularauricular muscles muscles –extrinsic and intrinsic,
n. facialis
Human earHuman ear
� collects and funnels the sound wavescollects and funnels the sound wavesinto the meatus
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 43
Human earHuman earExternal acoustic meatusExternal acoustic meatus , , meatusmeatus acusticus externusacusticus externus
�� conducts the sound wavesconducts the sound waves to the ear drum
NB:NB: The The ear waxear wax assistassists s in cleaning and lubrication, and also in cleaning and lubrication, and also
provides some protection from provides some protection from bacteria, fungibacteria, fungi, and , and insects!insects!
�� externalexternal auditoryauditory meatusmeatus (earear canalcanal), Lat. Lat. meomeo, a passage, a passage� length ~ 2.5 cm; 7 mm in diameter� S-shaped curve (140°)
�� structurestructure – two parts:�� cartilaginouscartilaginous partpart – outer⅓ (~8 mm long),
cartilago meatus acusticicartilago meatus acustici�� osseous partosseous part – inner ⅔ (~16 mm long),
meatus acusticus externusmeatus acusticus externus� thin skin; the thicker cerumen-producing ear canal
skin has fine hairs, tragi� sebaceous glands � in the hair follicles� ceruminous glands � ear wax, cerumen
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 44
� a structure of the sound conduction apparatussound conduction apparatus� primary functionsfunctions:
�� transmission of the vibrationstransmission of the vibrations of the tympanic membrane to the internal ear
� efficient transfertransfer of of acoustic energy acoustic energy from compression waves in air to fluid from compression waves in air to fluid ––membrane waves within the membrane waves within the cochleacochlea
�� tympanic membranetympanic membrane –membrana tympanimembrana tympani (tympanica)(tympanica)
�� tympanic cavity tympanic cavity –cavitas (cavum) tympanicavitas (cavum) tympani
�� auditory (eustachian) tubeauditory (eustachian) tube –tuba auditiva tuba auditiva (auditoria)(auditoria)
�� auditory ossiclesauditory ossicles –ossicula auditus ossicula auditus (auditoria)(auditoria)
Human earHuman ear
Middle earMiddle ear , , auris mediaauris media
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 45
�� ear drumear drum – thin, semisemi--transparenttransparent, nearly ovaloval in form:� longest diameter d=10-11 mm� shortest diameter d=8-9 mm
�� pars flaccidapars flaccida –Schrapnell’s membrane
�� pars tensapars tensa �� umboumbo� cuticular layer� fibrous layer –
absent in pars flaccida:� radiate fibers� circular fibers
� mucous layer
Human earHuman ear
Tympanic membraneTympanic membrane , , membrana tympanimembrana tympani
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 46
Human earHuman ear
Tympanic cavityTympanic cavity , , cavum tympanicavum tympani�� volumevolume – 1.5 cm3, air-filled�� diametersdiameters:
� vertical – 15 mm� transverse – 6-4-2 mm� antero-posterior – 15 mm
� two parts:parts:�� tympanic cavity propertympanic cavity proper�� epitympanic recessepitympanic recess
�� three clinically important levels:three clinically important levels:�� epitympanumepitympanum�� mesotympanummesotympanum�� hypotympanumhypotympanum
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 47
�� Eustachian (Eustachian ( pharyngotympanicpharyngotympanic ) tube) tube , links the pharynx to the middle ear, ~3.5 cm long:�� ostium tympanicum tubaeostium tympanicum tubae�� ostium pharyngeum auditivaeostium pharyngeum auditivae
� two parts:parts:�� cartilaginouscartilaginous partpart -- ⅔⅔ (cartilago tubae auditivae)(cartilago tubae auditivae) – 24 mm
�� bony partbony part -- ⅓⅓ ((in semicanalis tubae auditivae)semicanalis tubae auditivae) – 12 mm
�� isthmus tubae auditivaeisthmus tubae auditivae� mucous membrane – ciliated columnar epithelium
Human earHuman ear
Auditory tubeAuditory tube , , tuba auditivatuba auditiva
}
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 48
Human earHuman ear
Auditory ossiclesAuditory ossicles , , ossicula auditus ossicula auditus �� malleusmalleus – Lat. = mallet, hammerLat. = mallet, hammer; the largest, 8-9 mm long:
� head, caput mallei� neck, collum mallei� handle, manubrium mallei� anterior and lateral processes
�� incus incus – Lat. = anvilLat. = anvil:� body, corpus incudis� longprocess,crus longum
� lenticular process� short process, crus breve
�� stapes stapes – Lat. = stirrupLat. = stirrup:� head, caput stapedis� limbs (crura)
� anterius� posterius
� base, basis stapedis�� m. tensor tympani (Eustachii)m. tensor tympani (Eustachii)�� m. stapediusm. stapedius�� ligg. et artt. ossiculorum auditusligg. et artt. ossiculorum auditus
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 49
Human earHuman ear
Internal earInternal ear , , auris internaauris interna� location – in pars petrosa ossis temporalis� main functions:
�� converts sound waves into nerve impulsesconverts sound waves into nerve impulses� registers changes in equilibriumequilibrium
� composition:�� osseous labyrinth,osseous labyrinth,
labyrinthuslabyrinthus osseusosseus�� membranous labyrinthmembranous labyrinth,,
labyrinthuslabyrinthus membranaceusmembranaceus
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 50
�� vestibulevestibule, vestibulum�� three semicircular canalsthree semicircular canals,,
canales semicirculares::� canalis semicircularis lateralis� canalis semicircularis anterior� canalis semicircularis posterior
� cochlea� filled with perilymphperilymph
Human earHuman ear
Osseous labyrinth, Osseous labyrinth, labyrinthus osseuslabyrinthus osseus
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 51
VestibuleVestibule , , vestibulumvestibulum� lateral wall –
paries labyrinthicusparies labyrinthicus:� fenestra vestibuli �
closed by basis stapedis, fixed with lig. annulare stapedis
� fenestra cochleae �membrana tympani secundaria
� medial wall:�� ellipticalelliptical recessrecess �� utriculusutriculus�� vestibular crestvestibular crest ��
aqueduct of the vestibuleaqueduct of the vestibule�� spheroidspheroid recessrecess �� sacculussacculus�� cochlear recesscochlear recess�� maculae cribrosaemaculae cribrosae
pars vestibularis n. vestibulocochlearis::�� macula cribrosa superiormacula cribrosa superior�� macula cribrosa mediamacula cribrosa media�� macula cribrosa inferiormacula cribrosa inferior
Human earHuman ear
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 52
�� lateral semicircular canallateral semicircular canal (14 mm) – directed horizontallyhorizontally
�� anterioranterior (superior) semicircular canalsemicircular canal (18 mm) – verticalvertical in direction
�� posteriorposterior semicircular canal semicircular canal (22 mm) – directed sagittally backwards
� ⅔ of a circle
� diameter = all ~ 1 mm
� located in three perpendicular planes
� filled with semicircular ducts
� initial portion – ampulla osseaampulla ossea
� end part – crus osseumcrus osseum:�� simplex simplex – for lateral canal
�� communecommune – for anterior&posterior canals
Human earHuman ear
Semicircular canals, Semicircular canals, canales semicircularescanales semicirculares
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 53
Osseous cochleaOsseous cochlea�� spiral canalspiral canal,, canalis spiralis cochleaecanalis spiralis cochleae –
2½-2¾ turns (length ~ 3 cm):�height – 4-5 mm�base – 8-9 mm
�� basis cochleaebasis cochleae
�� cupula cochleaecupula cochleae� structure:
��modiolus modiolus –– Lat. Lat. the hub of a wheelthe hub of a wheel:� basis modioli �tractus spiralis foraminosus� lamina modioli� canalis spiralis modioli �ganglion cochleare
�� lamina spiralis ossealamina spiralis ossea � hamulushelicotrema
�� lamina spiralis secundarialamina spiralis secundaria �
membrana basilarismembrana basilaris
Human earHuman ear
Lat. Lat. cochleacochlea, snail shell, snail shell
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 54
Cochlear canalCochlear canal ,, canaliscanalis cochleariscochlearis��scala vestibuliscala vestibuli��scala tympaniscala tympani��scala mediascala media (ductus cochlearis)
� organum spirale Corti
Human earHuman ear
Lat.Lat. scalascala, stairway, stairway
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 55
� a closed system of fluid-filled membranous channels (sacs) of ectodermal origin
�� locationlocation – within the bony labyrinth� filled with endolymphendolymph� surrounded by perilymphperilymph –
perilymphatic space� labyrinthus vestibularislabyrinthus vestibularis ––
� within the osseous vestibule –utriculus and sacculus
� endolymphatic duct and sac� three semicircular ducts
�� labyrinthus cochlearis labyrinthus cochlearis ––� membranous cochlea
(cochlear duct)� spiral organ of Corti
Human earHuman ear
Membranous labyrinth, Membranous labyrinth, labyrinthus membranaceuslabyrinthus membranaceus
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 56
Vestibular labyrinthVestibular labyrinth , , labyrinthus vestibularislabyrinthus vestibularisHuman earHuman ear
�� utriculusutriculus – in recessus ellipticus:
�ductus utriculosaccularis
�macula utriculi – ⅔ mm: pars utricularis n. vestibulocochlearis
�� sacculus sacculus – in recessus sphericus:
�ductus reuniens �
ductus cochlearis
�macula sacculi – pars saccularis n. vestibulocochlearis
�� ductus ductus endolymphaticusendolymphaticus� saccus endolymphaticus
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 57
�� semicircular ductssemicircular ducts::�� ductus semicircularis lateralisductus semicircularis lateralis
�� ductus semicircularis anteriorductus semicircularis anterior
�� ductus semicircularis posteriorductus semicircularis posterior
� ¼ of the semicircular canals� ampulla membranacea� crus membranaceus:
� simplex – for lateral duct� commune – anterior&posterior ducts
� wall – thickened, three layers:
� inner – simple squamous epithelium� middle – vascular connective tissue� outer – fibrous tissue with blood vessels
clothed by flattened perilymphatic cells
Human earHuman ear
Vestibular labyrinthVestibular labyrinth , , labyrinthus vestibularislabyrinthus vestibularis
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 58
Human earHuman ear
Vestibular systemVestibular system�� Statoreceptor spotsStatoreceptor spots::�� macula utriculi macula utriculi andand macula sacculi:macula sacculi:
•• neuroepitheliumneuroepithelium:� epitheliocyti sensorii pilosi – 2 types
� 40-80 stereocilia; 1 kinocilium� epitheliocyti sustentantes•• membrana statoconiorummembrana statoconiorum –
otoliths, statoconia (Gr. oto-, ear + λιθος, lithos, a stone)
�� cristae ampullarescristae ampullares::•• neuroepitheliumneuroepithelium:� epitheliocyti sensorii pilosi – type I and II� epitheliocyti sustentantes•• cupula cupula – a glycoprotein substance
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 59
Human earHuman ear
Cochlear labyrinthCochlear labyrinth , , labyrinthus cochlearislabyrinthus cochlearis
�� cochlear duct, cochlear duct, ductus cochlearisductus cochlearis::
�scala media –endolymph
� length ~35 mm
� cecum vestibulare –in recessus cochlearis
� cecum cupulae –in cupula cochleae
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 60
Cochlear duct,Cochlear duct, ductus cochlearisductus cochlearis�� paries vestibularisparies vestibularis – vestibular membranevestibular membrane
((of ReissnerReissner) – two layers:� basal lamina
� simple squamous epithelium
�� paries externusparies externus:�� lig. spiralelig. spirale cochleaecochleae
�� striastria vascularisvascularis: three cell types:marginalmarginal, , intermediateintermediate and basaland basal – secrete endolymphendolymph
�� paries tympanicusparies tympanicus – basilarbasilar membranemembrane(membrana spiralismembrana spiralis)):� internal zone – sulcus spiralis internus, sulcus spiralis internus,
limbuslimbus spiralisspiralis (tympanic and vestibular lips �
membrana tectoriamembrana tectoria),
� middle zone – spiral organ of spiral organ of CortiCorti� external zone – sulcus spiralis externussulcus spiralis externus
Human earHuman ear
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 61
Spiral organ of Corti, organum spirale
� receptor (sensory) and supporting cells:�� internal and external rod (pillar) cellsinternal and external rod (pillar) cells of Cortiof Corti
� cuniculus internus (cuniculus internus (innerinner tunneltunnel of of Corti)Corti)� cuniculus medius (cuniculus medius (space ofspace of Nuel)Nuel)
�� internal phalangeal cellsinternal phalangeal cells ofof DeitersDeiters – 1 row andexternal phalangeal cellsexternal phalangeal cells ofof DeitersDeiters – 3 rows
�� internal (inner) hair cellsinternal (inner) hair cells – 1 row andexternal (outer) hair cellsexternal (outer) hair cells – 3 rows� cuniculus externus (cuniculus externus (outerouter tunnel)tunnel)
� epitheliocyti limitantes externiexterni(cells of Hensen) – 3-4 rows
� epitheliocyti sustentantes externi (cells of Claudius)
� supporting cells of Boettcher – beneathClaudius cells in the lower turn of the cochlea
� epitheliocyti limitantes interni – 1-2 rows� epitheliocyti sustentantes interni – 2-3 rows
Alfonso Corti (1822–1876)
� located onto basilar membrane: 100 µm basal, 500 µm apical turns
Human earHuman ear
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 62
Tectorial membraneTectorial membrane , , membrana tectoria (Cortii)membrana tectoria (Cortii)
� overlies the sulcus spiralis internus and the spiral organ of Corti�� secretedsecreted byby the epithelial cells of the
vestibular lipvestibular lip of theof the limbus laminae spiralislimbus laminae spiralis� colorless fibers embedded in a jelly-like matrix:
� 4 mm filaments of soft keratin� glycosaminoglycans
� covers the hair cells in organ of Corti, making contacts with their stereocilia
� the vibrating mechanism in the cochlea
Human earHuman ear
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 63
Mechanism of the auditory receptionMechanism of the auditory reception
Georg von BGeorg von Béékkéésysy((18991899--19721972))
�� Helmholtz Helmholtz resonance theoryresonance theory
�� RutherfordRutherford telephone theorytelephone theory
� travelling wave theory of BBéékkéésysy:
� basilar-membrane "resonance"
NB:NB: The The humanhuman ear can nominally hear ear can nominally hear soundssounds in the rangein the range 12 12 Hz Hz
toto 20,000 Hz20,000 Hz, with intensity levels from , with intensity levels from 0 0 toto 20 20 dB!dB!
Human earHuman ear
The Nobel Prize The Nobel Prize in Physiology or Medicine 1961in Physiology or Medicine 1961"for his discoveries of the physical "for his discoveries of the physical mechanism of stimulation within the cochlea"mechanism of stimulation within the cochlea"
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 64
}} laterallateral lemniscuslemniscus
Human earHuman ear
Auditory pathwaysAuditory pathways
�� IIstst neuronneuron –spiral ganglion:spiral ganglion:�� true bipolar neuronstrue bipolar neurons ––
3000030000--33000 33000 cellscells�� cell bodies in cell bodies in the spiral the spiral
structure of the cochleastructure of the cochlea�� peripheral processesperipheral processes
�� spiral organ of spiral organ of CortiCorti�� central processescentral processes
�� cochlear part of the cochlear part of the vestibulocochlear nervevestibulocochlear nerve
�� IIIIndnd neuronneuron ––cochlear nuclei:cochlear nuclei:�� dorsaldorsal cochlear nucleuscochlear nucleus�� ventralventral cochlear nucleuscochlear nucleus
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 65
�� IIIIIIrdrd neuronneuron – nucleus colliculi inferioris nucleus colliculi inferioris
�� IVIVthth neuronneuron – medial geniculate nucleusmedial geniculate nucleus
�� acoustic radiationacoustic radiation �� primary auditory primary auditory cortexcortex (A-I) = Brodmann’s area area 441 1 ((upper part of gyrus temporalis superior)
Human earHuman ear
Central auditory pathwaysCentral auditory pathways
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 66
Human earHuman ear
Vestibular pathwaysVestibular pathways
}} laterallateral lemniscuslemniscus
�� IIstst neuronneuron –vestibularvestibular ganglionganglion ((of of Scarpa):Scarpa):�� situated in the upper part of the outer situated in the upper part of the outer
end of the end of the internal auditory meatusinternal auditory meatus�� true bipolar neuronstrue bipolar neurons ––
~~220000 0000 cellscells�� peripheral processesperipheral processes ��
statoreceptor spots instatoreceptor spots in::•• maculae utriculi et sacculi maculae utriculi et sacculi ––linear accelerationlinear acceleration•• semicircular semicircular ducts ducts ––angular accelerationangular acceleration
�� central processescentral processes ��
vestibular part of the vestibular part of the vestibulocochlear nervevestibulocochlear nerve
�� IIIIndnd neuronneuron –– vestibular nuclei:vestibular nuclei:�� superior superior ((Bechterew) ) �� inferiorinferior ((Roller))�� medialmedial ((Schwalbe))�� laterallateral ((Deiters)) tractus spinocerebellaris posteriortractus spinocerebellaris posterior
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 67
�� tractus vestibulothalamicus tractus vestibulothalamicus –� nucleus ventralis posterolateralis
� nucleus ventralis posterior inferior
�� tractus thalamocorticalistractus thalamocorticalis –internal capsule � vestibular area ingyrus postcentralisgyrus postcentralis (area 3a)and around sulcus intraparietalissulcus intraparietalis
Human earHuman ear
Central vestibular pathwaysCentral vestibular pathways�� IIIIIIrdrd neuronneuron –– medial geniculate nucleusmedial geniculate nucleus
�� IVIVthth neuronneuron –– vestibular cortexvestibular cortex� rostral part of
gyrus temporalis superiorgyrus temporalis superior
Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 68
Thank youThank you……