meatus

Meatus, plural meatuses, is an anatomical term for a natural body passage or opening that leads to another cavity, duct, or canal. The word derives from Latin meatus, meaning passage or conduit. In humans, meatuses are openings that allow air, sound, urine, or other secretions to pass from one space to another.

Common examples include the external auditory meatus, the ear canal that conducts sound from the outer ear to the tympanic membrane; the nasal meatuses (superior, middle, and inferior), recesses beneath the corresponding nasal conchae that serve as air passages and as drainage pathways for the paranasal sinuses; and the urethral meatus, the external opening of the urethra, located at the penile tip in males and near the vaginal opening region in females.

Meatuses may also describe openings of ducts or structures within other organs, such as the meatus acusticus externus (external auditory meatus) or other regional names for natural conduits.

Functionally, meatuses serve as conduits for airflow, sound transmission, drainage, and exposure of mucosal surfaces to the environment. Clinically, narrowing or obstruction of a meatus—meatal stenosis—can impair drainage or flow and may require evaluation or intervention.

Outside humans, the term is used similarly in veterinary and comparative anatomy to denote analogous passages. See also urethral opening, nasal meatus, and the external auditory canal.