What is the Middle Ear Cleft?
The middle ear cleft is an anatomical system comprising the tympanic cavity (including the bony eustachian tube/protympanum), the middle ear cavity with its ossicles, and the mastoid air cell system—all interconnected to allow gaseous exchange and pressure regulation. 1
Anatomical Components
The middle ear cleft functions as an integrated system with several key structures:
The tympanic cavity contains the three ossicles (malleus, incus, and stapes) that are attached to the tympanic membrane and transmit sound vibrations 2, 3
The bony eustachian tube (protympanum) forms the anterior portion of the middle ear cleft and connects to the fibrocartilaginous eustachian tube 1
The mastoid air cell system extends posteriorly from the tympanic cavity, creating an interconnected network that allows for pressure equalization and gas exchange 4, 1
The middle ear cavity is separated from the outer ear by the tympanic membrane and connects to the inner ear via the oval window 2, 3
Functional Relationships
The middle ear cleft operates as part of a larger functional system:
Anteriorly, it connects through the eustachian tube to the nasopharynx, with the tensor veli palatini muscle actively opening the tube to promote ventilation 4
The eustachian tube protects the middle ear from excessive sound pressure and nasopharyngeal secretions while helping drain middle ear secretions through pumping action during opening and closing 4
The interconnected tympanic cavity and mastoid air cells allow for gaseous exchange and pressure regulation throughout the entire middle ear cleft system 1
Clinical Significance
Understanding the middle ear cleft anatomy is essential for comprehending middle ear pathology:
Chronic suppurative otitis media is defined as chronic inflammation of the middle ear and mastoid (the middle ear cleft) usually associated with tympanic membrane perforation and otorrhea 5
Eustachian tube dysfunction plays a central role in middle ear disease pathogenesis, as the tube's failure to ventilate properly affects the entire middle ear cleft system 4
Children with cleft palate experience nearly universal middle ear cleft disease because abnormal muscle insertions limit the eustachian tube's ability to open actively, resulting in chronic effusion throughout the system 2
Middle ear cleft opacification can occur as a sequela of external ear pathology, demonstrating the anatomical connections between ear regions 6