Aditus to mastoid antrum

Anatomical structure in the ear

The aditus to mastoid antrum is an important anatomical structure located in the temporal bone of the skull. It serves as a passage connecting the tympanic cavity to the mastoid antrum, which is part of the mastoid air cells system. This structure plays a crucial role in the ventilation and drainage of the middle ear.

Anatomy

The aditus to mastoid antrum is situated in the posterior wall of the tympanic cavity, above the level of the tympanic membrane. It is a narrow, funnel-shaped opening that leads into the mastoid antrum, a large air-filled space within the mastoid process of the temporal bone.

Location

The aditus is located superiorly to the facial nerve canal and posteriorly to the epitympanic recess. It is bordered by the tegmen tympani superiorly, which separates it from the middle cranial fossa.

Structure

The aditus is lined with a mucous membrane that is continuous with that of the tympanic cavity and the mastoid antrum. This continuity allows for the equalization of air pressure and drainage of secretions from the middle ear into the mastoid air cells.

Function

The primary function of the aditus to mastoid antrum is to facilitate the ventilation of the middle ear. It allows air to pass between the tympanic cavity and the mastoid air cells, helping to maintain equal air pressure on both sides of the tympanic membrane. This is essential for proper hearing function.

Additionally, the aditus provides a pathway for the drainage of any fluid or infection from the middle ear into the mastoid air cells, where it can be absorbed or further drained.

Clinical significance

The aditus to mastoid antrum is clinically significant because it can be involved in various ear pathologies. Infections of the middle ear, such as otitis media, can spread through the aditus into the mastoid antrum, leading to mastoiditis.

In surgical procedures, such as mastoidectomy, the aditus is an important landmark. Surgeons must carefully navigate this area to ensure proper drainage and ventilation of the middle ear while avoiding damage to nearby structures like the facial nerve.

Related pages

• Mastoid antrum
• Mastoid air cells
• Tympanic cavity
• Otitis media
• Mastoiditis

Gallery

• Aditus to mastoid antrum, shown in a diagram of the ear.

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  Location of the aditus to mastoid antrum in relation to the tympanic cavity.

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