Anatomy & Physiology of EarFatthi Abdel Baki MD 2010Middle Ear CleftInner EarExternal EarANATOMYAuricle(Pinna)External auditory canalExternal EarANATOMYANATOMYAuricleANATOMYExternal Auditory CanalCartilaginous partOuter 1/3: Cartilage Inner 2/3:Bone Examination Adult: up and backANATOMYExternal Auditory CanalCartilaginous partOuter 1/3: Hair follicles = furunculosisInner 2/3: No hair folliclesReferred Otalgia V: Trigeminal IX: Glossopharyngeal X: Vagus C2 & C3Middle Ear CleftInner EarExternal EarANATOMYMiddle Ear Cleft ANATOMYEustachian TubeANATOMYBony opening:PatentCartilaginous opening:Potentially closedOpens on yawning & swallowingFrom Middle ear To NasopharynxEustachian TubeChildrenANATOMYChildren ET:ShorterWiderMore horizontalInfection is commoner in infantsEustachian TubePhysiologyPhysiologyEqualize Pressure Middle & External EarMiddle Ear CavityWalls (6)ANATOMYMiddle Ear CavityLateral wallANATOMYMiddle Ear CavityLateral wall (Tympanic membrane)SkinFibrousMMPars TensaPars FlaccidaSkinMMMiddle Ear CavitySuperior wallANATOMYTegmen TympaniMiddle EarMCF (Temporal lobe)Middle Ear CavityMedial WallANATOMY(P)Middle Ear CavityMedial wallANATOMYMiddle Ear CavityPosterior wallANATOMYMastoidair cells: Cellular ScleroticANATOMYVertical part of facial nerve:Third part or mastoid partBony canalExit from stylomastoid foramenMiddle Ear CavityPosterior wallMiddle Ear CavityAnterior wallANATOMYANATOMYBony plate (thin) separating ME from IJVMiddle Ear CavityInferior wallMiddle Ear CavityPartsANATOMYEpitympanum (Attic):Above TMMesotympanum:Opposite TMHypotympanum:Below TMMiddle Ear CavityContentsANATOMYOssicles: 3Muscles: 2Nerve: 1Middle Ear CavityFunctionPhysiologyMagnification of soundsProtection of inner earfrom high soundsMiddle Ear CleftInner EarExternal EarANATOMYInner EarLabyrinthANATOMYHearing CochleaEquilibrium Vestibular apparatusInner EarLabyrinthANATOMYHearing CochleaEquilibrium Vestibular apparatusOuter Bony: PerilymphInner Membranous: EndolymphInner EarCochlea(P)PhysiologyInner EarCochleaPhysiologyANATOMYVestibule(utricle & saccule)SCCInner EarVestibular apparatusANATOMYSCC (3)Angular accelerationInner EarVestibular apparatusAmpulla of SCCCristae ampullarisCupulaCristaeAmpullaANATOMYVestibule Linear accelerationUtricle & SacculeMaculaeInner EarVestibular apparatusAbsorptionFormationCochlea: Stria vascularisEndolymphatic sacStria vascularisEndolymph (K+)Inner EarFluidANATOMYFormationCSFAbsorptionvenulesPerilymph (Poor K+)Inner EarFluidInternal Auditory CanalANATOMYFacial NerveVestibulocochlear NerveVasculatureANATOMYVasculatureANATOMY