Tympanic membrane

Dr Jeremy Jones et al.

The tympanic membrane is a thin membrane that separates the external ear from the middle ear. It acts to transmit sound waves from air in the external auditory canal to the ossicles of the middle ear.

The malleus is the first bone in the ossicular chain that eventually sees the sound wave transmitted to the oval window of the cochlea.

Gross anatomy

The tympanic membrane is shaped like a flat cone pointing into the middle and inner ear. It consists of three layers (from external to internal):

  1. cutaneum (skin)
  2. radiatum circulare (collagen fibres)
  3. mucosum (epithelium)

There are two distinct portions of the membrane:

  • pars tensa: the tense portion of the membrane is the larger portion and extends from the anterior and posterior malleolar folds at the level of the lateral process of the malleus to the inferior edge of the membrane
  • pars flaccida: the flaccid portion of the membrane is much smaller and is the portion of the membrane above the anterior and posterior malleolar folds 
Quadrant separation

It is anatomically separated into four quadrants:

  • anterosuperior
  • anteroinferior
  • posteroinferior
  • posterosuperior

This is important because vessels and nerves (specifically chorda tympani nerve) pass through the superior portion of the membrane. Additionally, the light reflex (cone of light) is specific to the anteroinferior portion of the membrane. Thus, when intervention is performed, the posteroinferior portion of the membrane is chosen.

Innervation

The membrane has two distinct nerve supplies based on the different embryological origins of the internal and external surfaces.

Related pathology


Head and neck anatomy
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Article Information

rID: 10522
System: Head & Neck
Section: Anatomy
Tag: refs
Synonyms or Alternate Spellings:

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