Middle Ear Anatomy

Move the cursor over the graphic to identify structures

The middle ear (ME) and contents serve to transmit external sound energy to the components of the inner ear. Sound pressure applied to the ear drum (tympanum) creates motion which is transmitted through the ossicles to the oval window. The oval window membrane is the interface with the inner ear. The inner ear is where motion is translated to neural signals.

At rest, the eustachian tube is collapsed closed. During the acts of swallowing or yawning, air is allowed to enter the lumen through an orifice within the nasopharynx

The tube opens by contraction of the dilator tubae muscle. The dilator tubae is the medial bundle of the tensor veli palantini muscle.

Any condition which affects the function of the dilator tubae will affect the patient's ability to aerate and drain the ME. Conditions which can limit efficient contraction of the dilator tubae muscles include:

  • craniofacial defects such as cleft palate, trisomy 21, etc.
  • craniofacial trauma,
  • neuromuscular defects,
  • tumors, etc.


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The dilator tubae contracts to close the opening of the eustachian tube.


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