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Anatomy of ear
The document summarizes the anatomy of the ear. It describes the three main parts of the outer ear: the auricle, external acoustic canal, and tympanic membrane. It then discusses the middle ear in detail, including the bones (malleus, incus, stapes) and muscles (tensor tympani, stapedius). Finally, it briefly outlines the three sections of the inner ear: the vestibule, semicircular canals, and cochlea. The ear has a complex anatomy that allows it to receive sound waves and transmit signals to the brain.
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Anatomy of ear
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- 2. components Auricle External acoustic canal Tympanicmembrane pgmedicalworld.com
- 3. Auricle /pinna single pieceof yellow elastic cartilage covered with skin Closely adherant to perichondrium on lateral surface than medial Incisura terminalis: no cartilage between tragus n crus of helix .incision in this area for epidural approach use: as source of source of graft for reconstruction surgery of middle ear etc pgmedicalworld.com
- 4. External acaustic /auditorycanal 24 cms along posterior wall upper wall directed upwards, backwards, medially Inner part: downwards, forwards ,medially For allignment :pulled upwards, backwards, medially pgmedicalworld.com
- 5. (a)Cartilagenous part 8mm has 2deficiencies:fissure of santorini; part through which parotid or superior mastoid infection occur Furuncles(staphylococcal infection) in outer 1/3 of canal due to hair follicles pgmedicalworld.com
- 6. (b)Bony part 16mm devoidof hair, ceruminous glands 6mm lateral to tympanic membrane bony meatus presents narrowing :”isthmus” Anteroinferior part of deep meatus beyond isthmus presents recess-”ant recess” Anteeroinferior part of bony canal may presents deficiency (foramen of huschke) pgmedicalworld.com
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- 8. Tympanic memb/ear drum 9-10mmtall,8-9mm wide,.1mm thick Divided into 2 parts (a) pars tensa Thick perifery ,form fibrocartlagenous ring called ”annulus tympanicus” Central part tensed inwards at tip of malleus ‘UMBO’ pgmedicalworld.com
- 9. (b)Pars flacida /shrapnelsmembrane Between notch of rivinus n anterior n posterior malleal folds LAYERS OF TYMPANIC MEMBRANE Outer epIthelial layer Inner mocosal layer Middle fibrous layer pgmedicalworld.com
- 10. Nerve supply ofexternal ear Greater auricular nerve Lesser occipital nerve Auriculo temporal nerve Auricular branch of vagus EXTERNAL AUDITORY CANAL Facial nerve Auriculo temporal nerve Auricular br of vagus nerve TYMPANIC MEMBRANE Auriculo temporal nerve Auri br of vagus nerve Jacobsons nerve pgmedicalworld.com
- 11. MIDDLE EAR Middle earcleft: eustachian tube,aditus,antrum,mastoid air cells Divided into: mesotympanium,epitympanum,hypotympanum Linked to 6 sided box pgmedicalworld.com
- 12. roof Formed by thinplate of bone : tegmen tympani,forms roof of aditus n antrum FLOOR Thin plate of bone seperates tympanic cavity from jug bulb ANTERIOR WALL Thin plate of bone seperates cavity from internal carotid art 2 openings: eustachian tube, tensor tympani muscle pgmedicalworld.com
- 13. Posterior wall Close tomastoid air cells Presents bony progectn”pyramid”,tendon of stapedius is attachad to neck of stapes Surgically important as direct access can be made through middle ear Facial recess/ posteauor sinus: depression in post wall lateral to pyramid pgmedicalworld.com
- 14. Medial wall Formed bylabyrinth Presents bulge” promontary” Oval window fixed to foot plate Round window covered by sec tympanic membrane Over oval window is canal for facial n Just anterior to oval window, hook like progection” pocessus cochleariformis” pgmedicalworld.com
- 15. Lateral wall Formed bytympanic membrane n bony outer attic wall ”scutum” OSSICLES OF MIDDLE EAR pgmedicalworld.com
- 16. Malleus:head,neck,handle,lateral and anteriorprocess Incus:body,short and long process Stapes: head, neck, anterioe and posterior crura, foot plate INTRA TYMPANIC MUSCLES Tensor tympani stapedius pgmedicalworld.com
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- 18. Bony and membranouslabyrinth filled with endolymph and perylymph respectively Bony labyrinth 3 parts:vestibule,semicircular canals,cochlea Vestibule:the central canal of labrynth Latwral wall:oval window Medial wall: 2 recess: spherical and elliptical Below opening of elliptical recess is opening of aqueous duct through which passes endolymphatic duct Posterior part of vestibule:5 openings of semisircular canals pgmedicalworld.com
- 19. Semicircular canals3 innumber: lateral,posterior,superior at right angles to each other Has amputated n nonamputated end, Nonamputated ends of posterior n superior canals unite to form channel ”crus commune” conchae Coiled tube making2.5-2.75 turns round central pyranid ”modiolus” “osseous spiral lamina”:around modiolus winding spirally like thread of screw 3 componants: scala vestibuli Scala tympani Scala mediapgmedicalworld.com
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