Sense Organsdownloads.imune.net/medicalbooks/Sense Organs in pictures... · 2018-06-29 · Sense...

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


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


�� 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


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


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


�� 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!


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


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


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


�� 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


�� 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


�� 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


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


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


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!!


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


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


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


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


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


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


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


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


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””


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!


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


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


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


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


Human eyeHuman eye

Accessory visual apparatusAccessory visual apparatus

�� Extraocular musclesExtraocular muscles

�� Eyebrows and eyelidsEyebrows and eyelids

�� ConjunctivaConjunctiva

�� Lacrimal apparatusLacrimal apparatus


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


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


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


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


Human eyeHuman eye

Human lacrimal apparatusHuman lacrimal apparatus

�� lacrimal glandlacrimal gland

�� lacrimal canaliculilacrimal canaliculi

�� lacrimal saclacrimal sac

�� nasolacrimalnasolacrimal (tear)(tear) ductduct


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


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


� 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


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


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


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


� 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


�� 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


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


�� 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

}


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


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


�� 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


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


�� 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


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


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


� 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


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


�� 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


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


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


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


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


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


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"


}} 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


�� 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


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


�� 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


Thank youThank you……

Sense Organsdownloads.imune.net/medicalbooks/Sense Organs in pictures... · 2018-06-29 · Sense...

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Transcript of Sense Organsdownloads.imune.net/medicalbooks/Sense Organs in pictures... · 2018-06-29 · Sense...