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The Temporal Bone

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The Temporal Bone TheThe TemporalTemporal BoneBone Dr K Lehmann Division of Otorhinolaringology University of Stellenbosch and Tygerberg Hospital FourFour elementselements fusefuse toto formform temporaltemporal bonebone •• PetromastoidPetromastoid •• SquamousSquamous •• TympanicTympanic •• StyloidStyloid processprocess TemporalTemporal bonebone TemporalTemporal bonebone PetromastoidPetromastoid •• PetrousPetrous (G:(G: Petra:Petra: Rock)Rock) •• DerivedDerived fromfrom thethe petrouspetrous bonebone •• Dense,Dense, bonybony massmass –– OssificationOssification ofof cartilagenouscartilagenous oticotic capsulecapsule –– 1616th weekweek (embrio)(embrio) –– NoNo suturesuture lineslines PetromastoidPetromastoid (continued) •• ContainsContains importantimportant structures:structures: –– InnerInner earear (labyrinth)(labyrinth) • Cochlea, semi-circular canals –– InternalInternal acousticacoustic meatusmeatus • Facial nerve, vestibulo cochlear nerve, (superior and inferior), intermediate nerve,nerve, internal auditory artery and vein) –– CanalCanal forfor facialfacial nervenerve • Fallopian canal –– MastoidMastoid airair cellscells PetromastoidPetromastoid (continued) •• Forms:Forms: –– RoofRoof andand floorfloor ofof middlemiddle earear –– LateralLateral halfhalf ofof EustachianEustachian tubetube –– BaseBase ofof skullskull PetromastoidPetromastoid SquamousSquamous •• StartsStarts toto ossifyossify fromfrom aa singlesingle centrecentre atat rootroot ofof zygomazygoma •• 88th weekweek (embryo)(embryo) •• PosteriorPosterior inferiorinferior partpart growsgrows downdown behindbehind thethe tympanictympanic ringring –– FormsForms laterallateral wallwall ofof fetalfetal mastoidmastoid antrumantrum TympanicTympanic •• StartsStarts toto ossifyossify fromfrom severalseveral centrescentres aroundaround thethe externalexternal meatusmeatus •• FormsForms aa ringring withwith aa groovegroove ÆÆ sulcussulcus forfor tympanictympanic membranemembrane (annulus)(annulus) •• ContainsContains thethe bonybony passagepassage fromfrom thethe auricle:auricle: –– TheThe externalexternal acousticacoustic meatusmeatus StyloidStyloid processprocess •• Slender,Slender, pointedpointed bonebone •• NotNot fullyfully developeddeveloped atat birthbirth •• GivesGives attachmentattachment toto certaincertain ligamentsligaments andand musclesmuscles ((egeg stylohyoidstylohyoid muscle,muscle, posteriorposterior bellybelly ofof digastricdigastric muscle)muscle) •• LiesLies nextnext toto stylomastoidstylomastoid foramen:foramen: facialfacial nervenerve TemporalTemporal bonebone (articulation; processus) •• ArticulatesArticulates atat suturessutures withwith parietal,parietal, occipital,occipital, sphenoidsphenoid andand zygomaticzygomatic bonesbones •• ZygomaticZygomatic processprocess ofof temporaltemporal bonebone unitesunites withwith temporaltemporal processprocess ofof zygomaticzygomatic bonebone toto formform zygomaticzygomatic archarch •• ZygomaticZygomatic processprocess ofof temporaltemporal bonebone articulatesarticulates withwith headhead ofof mandiblemandible atat mandibularmandibular fossafossa •• ZygomaticZygomatic arches:arches: widestwidest partsparts ofof face,face, commonlycommonly fracturedfractured andand depresseddepressed CranialCranial fossaefossae •• Anterior,Anterior, middlemiddle andand posteriorposterior (largest)(largest) •• LodgesLodges variousvarious partsparts ofof thethe centralcentral nervousnervous systemsystem •• Anterior:Anterior: – Frontal lobes of cerebral hemispheres •• Middle:Middle: – Anterior extremities of temporal lobes (temporal poles); and half of inferior surface of temporal lobe •• Posterior:Posterior: – Cerebellum, pons and medulla CranialCranial fossaefossae PosteriorPosterior cranialcranial fossafossa •• FormedFormed largelylargely byby thethe inferiorinferior andand anterioranterior partsparts ofof occipitaloccipital bonebone •• Also:Also: – Body of sphenoid – Petromastoid part of temporal bone •• TentoriumTentorium cerebellicerebelli coverscovers thethe cerebralcerebral hemisphereshemispheres andand thethe occipitaloccipital lobeslobes lielie onon thethe tentoriumtentorium cerebellicerebelli,, superiorsuperior toto thethe posteriorposterior cranialcranial fossafossa CranialCranial foraminaforamina •• ManyMany foraminaforamina (l.(l. openings)openings) perforateperforate thethe basebase ofof skullskull •• MostlyMostly theythey areare forfor thethe passagepassage ofof thethe twelvetwelve cranialcranial nervesnerves (some(some areare forfor bloodvesselsbloodvessels)) •• PresencePresence ofof allall thethe foraminaforamina andand thinthin areasareas ofof bonebone inin thethe cranialcranial floorfloor makemake thethe skullskull basebase fragilefragile andand vulnerablevulnerable toto fracturefracture andand toto invasioninvasion byby malignancymalignancy (primary(primary oror metastaticmetastatic disease)disease) ForaminaForamina •• AnteriorAnterior cranialcranial fossafossa:: –– CribiformCribiform plate:plate: axonsaxons ofof olfactoryolfactory cellscells •• MiddleMiddle cranialcranial fossafossa:: –– SphenoidSphenoid bonebone andand petrouspetrous partpart –– temporaltemporal bonebone –– MostMost foraminaforamina foundfound inin sphenoidsphenoid bone,bone, butbut cranialcranial nervesnerves foundfound closeclose toto petrouspetrous partpart ofof temporaltemporal bonebone ForaminaForamina MiddleMiddle cranialcranial fossafossa (continued) •• CrescentCrescent ofof foraminaforamina foundfound inin thethe greatergreater windwind ofof sphenoid:sphenoid: FourFour constantconstant foramina:foramina: •• SuperiorSuperior orbitalorbital fissurefissure:: communicationcommunication betweenbetween middlemiddle cranialcranial fossafossa andand orbitorbit –– CNCN III,III, IV,IV, VIVI –– FrontalFrontal nervenerve (CN(CN VV1)) MiddleMiddle cranialcranial fossafossa (continued) •• ForamenForamen rotundumrotundum:: –– MaxillaryMaxillary nervenerve (CN(CN VV2)) •• ForamenForamen ovaleovale:: –– MandibularMandibular nervenerve (CN(CN VV3)) •• ForamenForamen spinosumspinosum:: –– MiddleMiddle meningealmeningeal arteryartery (largest)(largest) MiddleMiddle cranialcranial fossafossa (continued) •• TheThe foramenforamen lacerumlacerum isis locatedlocated betweenbetween basebase ofof sphenoidsphenoid andand apexapex ofof petrouspetrous partpart ofof temporaltemporal bonebone •• ContainsContains thethe internalinternal carotidcarotid arteryartery PosteriorPosterior cranialcranial fossafossa •• ForamenForamen magnum:magnum: – Largest – Unpaired – Junction of medulla and spinal cord •• UsuallyUsually ovaloval--shapedshaped •• LiesLies atat mostmost inferiorinferior partpart ofof middlemiddle cranialcranial fossa,fossa, midwaymidway betweenbetween thethe mastoidmastoid processesprocesses •• CNCN XI:XI: spinalspinal rootsroots PosteriorPosterior cranialcranial fossafossa (continued) •• JugularJugular foramen:foramen: – Between occipital bone and petrous part of temporal bone – CN IX (glossopharyngeal nerve) – CN X (vagus nerve) – CN XI (accessory nerve) •• SuperiorSuperior bulbbulb ofof internalinternal jugularjugular vein.vein. ContainsContains thethe tympanictympanic body:body: chemoreceptorchemoreceptor tissue.tissue. TumourTumour ÆÆ causecause symptomssymptoms owingowing toto neighbouringneighbouring cranialcranial nervesnerves PosteriorPosterior cranialcranial fossafossa (continued) •• HypoglossalHypoglossal foramen:foramen: –– CNCN XIIXII (hypoglossal(hypoglossal nerve)nerve) PosteriorPosterior cranialcranial fossafossa SummarySummary •• TemporalTemporal bone:bone: fourfour partsparts •• HousesHouses importantimportant structuresstructures •• PetrousPetrous part:part: –– HardestHardest bonebone inin bodybody –– ContainsContains innerinner andand middlemiddle earear –– AdultAdult sizesize atat birthbirth –– ThusThus cochleacochlea isis adultadult sizesize atat birthbirth SummarySummary (continued) •• CranialCranial nervesnerves runrun throughthrough foramina;foramina; skullskull basebase succeptablesucceptable toto fracturesfractures andand infiltrationinfiltration byby malignancymalignancy •• Clinically:Clinically: – CN fall out might be only sign of pathology – If clinically suspected; can be visualized by CT/MRI •• MustMust bebe ableable toto testtest forfor cranialcranial nervenerve functionfunction andand makemake connectionconnection ExamplesExamples •• CNCN IX;IX; X;X; XIXI fallfall out;out; andand pulsatilepulsatile tinnitus:tinnitus: glomusglomus jugularejugulare •• CNCN V;V; VIVI fallfall out;out; pain:pain: GradenigoGradenigo syndrome:syndrome: malignantmalignant otitisotitis externaexterna •• CNCN VII;VII; VIII:VIII: temporaltemporal bonebone fracturefracture •• CNCN VIII:VIII: unilateral:unilateral: acousticacoustic neuromaneuroma •• CNCN V;V; VI;VI; inin patientpatient withwith prostateprostate CA:CA: metastaticmetastatic diseasedisease toto petrouspetrous apexapex.
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