Tympanic Membrane

Tympanic Membrane


TYMPANIC MEMBRANE

  • Obliquely set so that postero-superior part is more lateral than antero-inferior part
  • 9-10mm tall; 8-9mm wide; 0.1mm thick.
  • Normal colour of tympanic membrane is pearly white.
  • The most mobile part of the tympanic membrane is peripheral part.
  • The distance between tympanic membrane and medial wall of middle ear at the level of center is 2 mm.
  • Surface area of tympanic membrane is 90 mm2.
  • The effective diameter of the tympanic membrane is 45 mm2.
  • Lever ratio of tympanic membrane is 1.3-1.

Pars tensa

  • Forms most part of tympanic membrane
  • Periphery thickened to form annulus tympanicus
  • Central part is tented inwards at the level of tip of malleus and is called the umbo
  • Handle of Malleus is attached to the center of the tympanic membrane.
  • Umbo is the most reliable landmark in otoscopy
  • A bright cone of light seen radiating from the tip of malleus to the periphery in the antero¬inferior quadrant

Pars flaccida (Shrapnel’s membrane)

  • Situated above the lateral process of malleus between the notch of Rivinus and the anterior and posterior malleal (earlier called malleolar) folds.

NERVE SUPPLY OF TYMPANIC MEMBRANE

  • Anterior half of lateral surface- auriculotemporal
  • Posterior half of lateral surface- Arnolds nerve
  • Medial surface – tympanic branch of 9th nerve (Jacobson’s N)

EMBRYOLOGY OF TYMPANI MEMBRANE

  • Tympanic membrane develops from all the three germinal layers-represents all the 3 components of the embryonic disc

CLINCAL SIGNIFICANCE OF TYMPANIC MEMBRANE

  • Most common site of perforation of tympanic membrane in ASOM is Anterior inferior quadrant.
  • Rupture of an ear drum may occur at the noise level above 160 dB.
  • The treatment of traumatic rupture of tympanic membrane is no active treatment.
  • The hearing loss after rupture of tympanic membrane is 10-40 db.
  • Use of nitrous oxide is contraindicated during Tympanic Membrane Grafting Surgery.
  • The torture method involving simultaneous beating of both ears with palms of hand, resulting in rupture of tympanic membrane is called Telefono.
  • Uses of  of Siegel’s Speculum during Ear Examination are Magnification ,Assessment of movement of the tympanic membrane, As applicator for the powdered antibiotic of ear and to suck out middle ear secretions in patients with chronic serous ottitis media.
  • In a case of conductive hearing loss of 55 db with normal cochlera reserve,due to accident,with normal tympanic membrane,the tympanogram would show Ad type of Curve.It occurs due to Ossicular Discontinuity.
  • Maximum hearing loss occur when there is ossicular interruption with intact tympanic membrane (54dB).
  • Glomus Tumor-Otoscopy shows a red reflex through intact tympanic membrane. “Pulsation sign” is positive, progressive deafness and pulsatile  tinnitus.
  • Normal consciousness and blood in the tympanic membrane may be found in a case of Basilar fracture due to head injury. 
  • The presence of conductive type of hearing loss, dull tympanic membrane and type B tympanogram suggests the presence of middle ear cavity or serous otitis media.
  • Serous otitis media in an older individual should raise the suspicion of nasopharyngeal malignancy. The presence of enlarged lymph nodes adds to the suspicion.
  • Chalky white tympanic membrane is seen in Tympanosclerosis.
  • Features of moderately retracted tympanic membrane : Handle of malleus appearance foreshortened ,Cone of light is absent or interrupted , Lateral process of malleus becomes more prominent,Non prominent Umbo.
  • Bluish tympanic membrane is seen in Glue  ear(Secretory Otitis Media).
  • Myringoplasty is plastic repair of Tympanic membrane,done with Operating Microscope.
  • Procedure of surgical opening in Tympanic Membrane is Myringotomy.
  • Tympanoplasty is eradication of middle ear disease with reconstruction of tympanic membrane & ossicles.
  • Thin painless otorrhoea, multiple perforations of the tympanic membrane and failure to respond to antimicrobial treatment is characteristic of Tubercular Otitis Media.
  • Areas of spontaneously healed tympanic membrane are called Dimeric.
Exam Question
 
  • Most common site of perforation of tympanic membrane in ASOM is Anterior inferior quadrant.
  • Rupture of an ear drum may occur at the noise level above 160 dB.
  • Use of nitrous oxide is contraindicated during Tympanic Membrane Grafting Surgery.
  • The torture method involving simultaneous beating of both ears with palms of hand, resulting in rupture of tympanic membrane is called Telefono.
  • Uses of  of Siegel’s Speculum during Ear Examination are Magnification ,Assessment of movement of the tympanic membrane, As applicator for the powdered antibiotic of ear and to suck out middle ear secretions in patients with chronic serous ottitis media. 
  • In a case of conductive hearing loss of 55 db with normal cochlera reserve,due to accident,with normal tympanic membrane,the tympanogram would show Ad type of Curve.It occurs due to Ossicular Discontinuity.
  • Maximum hearing loss occur when there is ossicular interruption with intact tympanic membrane (54dB).
  • Glomus Tumor-Otoscopy shows a red reflex through intact tympanic membrane. “Pulsation sign” is positive, progressive deafness and pulsatile tinnitus
  • Handle of Malleus is attached to the center of the tympanic membrane.
  •  The presence of conductive type of hearing loss, dull tympanic membrane and type B tympanogram suggests the presence of fluid in middle ear cavity or serous otitis media.
  •  Serous otitis media in an older individual should raise the suspicion of nasopharyngeal malignancy. The presence of enlarged lymph nodes adds to the suspicion.
  • Tympanic membrane develops from all the three germinal layers-represents all the 3 components of the embryonic disc.
  • Auriculotemporal nerve is one of the nerves providing sensation to the tympanic membrane.
  • The treatment of traumatic rupture of tympanic membrane is no active treatment.
  • Normal consciousness and blood in the tympanic membrane may be found in a case of Basilar fracture due to head injury.
  • Normal colour of tympanic membrane is pearly white.
  • The most mobile part of the tympanic membrane is peripheral part.
  • Pars flaccida of the tympanic membrane is also called Shrapnell’s membrane. 
  • The distance between tympanic membrane and medial wall of middle ear at the level of center is 2 mm.
  • Surface area of tympanic membrane is 90 mm2.
  • The effective diameter of the tympanic membrane is 45 mm2. 
  • Lever ratio of tympanic membrane is 1.3-1.
  • The hearing loss after rupture of tympanic membrane is 10-40 db.
  • Chalky white tympanic membrane is seen in Tympanosclerosis.
  • Features of moderately retracted tympanic membrane : Handle of malleus appearance foreshortened ,Cone of light is absent or interrupted , Lateral process of malleus becomes more prominent,Non prominent Umbo.
  • Bluish tympanic membrane is seen in Glue  ear(Secretory Otitis Media).
  • Myringoplasty is plastic repair of Tympanic membrane,done with Operating Microscope.
  • Procedure of surgical opening in Tympanic Membrane is Myringotomy.
  • Tympanoplasty is eradication of middle ear disease with reconstruction of tympanic membrane & ossicles.
  • Thin painless otorrhoea, multiple perforations of the tympanic membrane and failure to respond to antimicrobial treatment is characteristic of Tubercular Otitis Media.
  • Areas of spontaneously healed tympanic membrane are called Dimeric.
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