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Tegmen Tympani

tegmen tympani

The tegmen tympani is the thin bony roof of the middle ear cavity (tympanic cavity), formed by the petrous temporal bone. It separates the middle ear from the middle cranial fossa dura and the temporal lobe. The same plate continues anteriorly as the tegmen mastoideum (roof of the mastoid antrum and air cells). The tegmen is typically only 1-2 mm thick and may have dehiscences.

Region: Head & Skull

Clinical Relevance

Clinical Notes

The tegmen tympani is eroded by cholesteatoma, chronic suppurative otitis media, and granulation tissue, creating a direct path for infection from the middle ear to the extradural and intracranial spaces. Tegmen dehiscence, whether congenital or erosive, predisposes to intracranial complications of otitis media including meningitis, extradural abscess, and temporal lobe abscess. In cochlear implant surgery and mastoidectomy, the tegmen is the superior limit of dissection. Tegmen repair with temporalis fascia and bone dust is performed when iatrogenic or disease-related defects create a dural communication.

Pathology

Common Injuries & Conditions

Cholesteatoma Erosion of Tegmen Tympani

Cholesteatoma enzymatically erodes the tegmen tympani, creating a middle ear-intracranial communication visible on CT as loss of the tegmen plate; complications include extradural abscess, meningitis, and temporal lobe abscess, requiring combined otological and neurosurgical management with tegmen defect repair.