The middle ear cavity (tympanic cavity) is an air-filled space within the temporal bone between the tympanic membrane laterally and the medial wall (containing the oval and round windows and the cochlear promontory). It contains the ossicular chain (malleus, incus, stapes), the chorda tympani crossing it, the facial nerve in its tympanic segment above the oval window, and the tympanic plexus on the promontory. It communicates with the mastoid via the aditus ad antrum and with the nasopharynx via the Eustachian tube.
| Location | Air-filled space in the petrous part of the temporal bone, between the eardrum and the inner ear |
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| Parts |
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| Nerve Supply | Tympanic nerve of the glossopharyngeal nerve (tympanic plexus, sensory); Chorda tympani (passes through); Facial nerve in the medial wall and its branch to stapedius; Nerve to tensor tympani (mandibular nerve) |
| Blood Supply | Anterior tympanic artery (maxillary); Stylomastoid artery (posterior auricular); Superior tympanic and petrosal branches (middle meningeal); Inferior tympanic artery (ascending pharyngeal) |
Converts airborne sound into fluid waves in the inner ear through the ossicles, boosting pressure about twentyfold. The auditory tube keeps its air pressure equal to the outside.
The middle ear cavity is the site of otitis media, cholesteatoma, glomus tympanicum, and conductive hearing loss from ossicular dysfunction. Acute otitis media in children arises from Eustachian tube dysfunction allowing nasopharyngeal bacteria to enter the middle ear. Chronic suppurative otitis media (CSOM) with or without cholesteatoma destroys the ossicles and adjacent structures. Middle ear anatomy guides surgical approaches: tympanotomy (posterior tympanotomy facial recess approach) provides access to the round window for cochlear implant electrode placement.
Keratinising squamous epithelium migrating through a marginal tympanic membrane perforation or retraction pocket fills the middle ear cavity with keratin debris, eroding the ossicles and adjacent bony structures including the tegmen, facial canal, and labyrinth; canal-wall-down or canal-wall-up mastoidectomy removes the cholesteatoma with reconstruction of the hearing mechanism.
