Mittellohr

The Mittellohr, or middle ear, is an air-filled cavity in the temporal bone that constitutes the middle portion of the auditory system. It lies between the external auditory canal, separated by the tympanic membrane, and the inner ear, connected to the nasopharynx by the Eustachian tube. The cavity contains the auditory ossicles: the malleus (hammer), incus (anvil), and stapes (stirrup).

The tympanic membrane vibrates in response to sound and transmits movements to the ossicles. The malleus is attached to the drum, the incus bridges to the stapes, whose footplate interfaces with the oval window of the inner ear. The round window provides a pressure-relief opening for cochlear fluid. The middle ear also houses small muscles and nerves that regulate movement of the ossicles.

Functionally, the middle ear conducts and amplifies sound from air to the fluid-filled inner ear. The ossicular chain provides impedance matching, increasing the effective pressure at the oval window. The Eustachian tube equalizes middle-ear pressure and enables drainage to the nasopharynx. The stapedius and tensor tympani muscles modulate vibration to protect the inner ear from extremely loud sounds, a reflex known as the acoustic reflex.

The blood supply comes from tympanic branches of the maxillary artery and other nearby vessels; venous drainage occurs through a network to surrounding venous systems. Innervation is mainly via the tympanic plexus, formed by branches of the glossopharyngeal nerve, with motor innervation to the adjacent muscles by the facial nerve and mandibular branch of the trigeminal nerve. The ossicles and cavity develop from the first and second pharyngeal arches.

Clinically, the Mittellohr is associated with otitis media (acute or chronic), otosclerosis with stapes fixation, cholesteatoma, and tympanic membrane perforation. Diagnosis relies on otoscopy and tympanometry, often complemented by audiometry; computed tomography is used to assess chronic disease and bony involvement.