Anatomy of ear

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Anatomy of ear

  1. 1. Anatomy of ear pgmedicalworld.com
  2. 2. components Auricle External acoustic canal Tympanic membrane pgmedicalworld.com
  3. 3. Auricle /pinna single piece of 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. 4. External acaustic /auditory canal 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. 5. (a)Cartilagenous part 8mm has 2 deficiencies: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. 6. (b)Bony part 16mm devoid of 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
  7. 7. pgmedicalworld.com
  8. 8. Tympanic memb/ear drum 9-10mm tall,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. 9. (b)Pars flacida /shrapnels membrane 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. 10. Nerve supply of external 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. 11. MIDDLE EAR Middle ear cleft: eustachian tube,aditus,antrum,mastoid air cells Divided into: mesotympanium,epitympanum,hypotympanum Linked to 6 sided box pgmedicalworld.com
  12. 12. roof Formed by thin plate 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. 13. Posterior wall Close to mastoid 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. 14. Medial wall Formed by labyrinth 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. 15. Lateral wall Formed by tympanic membrane n bony outer attic wall ”scutum”  OSSICLES OF MIDDLE EAR pgmedicalworld.com
  16. 16. Malleus:head,neck,handle,lateral and anterior process Incus:body,short and long process Stapes: head, neck, anterioe and posterior crura, foot plate INTRA TYMPANIC MUSCLES Tensor tympani stapedius pgmedicalworld.com
  17. 17. THE INTERNAL EAR pgmedicalworld.com
  18. 18. Bony and membranous labyrinth 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. 19. Semicircular canals3 in number: 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
  20. 20. THANK YOU pgmedicalworld.com

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