Protympanum

The protympanum (rare plural: protympana) is the compartment of the middle ear cavity located anterior to the coronal plane defined by the anterior margin of the tympanic annulus. Some authors consider the protympanum the anterior part of the mesotympanum rather than a separate compartment or do not mention it at all as a major compartment .

Gross anatomy

Relations and/or boundaries

Anteriorly, the protympanum includes most or all of the bony portion of the Eustachian tube .

Posteriorly, the protympanum widely opens to the mesotympanum.

Laterally, the wall of the protympanum is a piece of bone called the lateral lamina that separates the middle ear cavity from the mandibular (glenoid) fossa.

Medially, the wall of the protympanum is the carotid plate.

Superiorly, the protympanum is delimited from the attic (epitympanum) by the semicanal for the tensor tympani muscle and the tensor tympani fold .