The eustachian tube is a small passage that connects the pharynx to the middle ear. When sneezing, swallowing or yawning, the body’s eustachian tube opens to allow gas to pass through, which prevents air pressure and fluid from building up in the ear. The eustachian tube in infants is about 17.5 mm and then continues to grow to a length of about 37.5 mm in adulthood. The eustachian tube is most commonly known for its role in equalizing the pressure within the middle ear. The eustachian tube serves three purposes: pressure equalization in the middle ear, expelling air from the middle ear, and protecting the middle ear from bacteria or viruses. On average, the eustachian tube opens one to two times per hour. When opened, it usually remains open for only about 0.3 to 0.5 seconds. However, when yawning, the eustachian tube opens more frequently and for longer periods of time. When the pressure in the ear is uneven during changes in altitude and weather, the eardrum changes shape. In the absence of equal pressure, the eardrum does not respond to sound in the same way and hearing is affected. At the same time the body may feel pain and in extreme cases the eardrum may rupture. – The eustachian tube connects the middle ear to the nasopharynx and has triangular to oval openings at both ends. The eustachian tube is a very important organ of the body and should be protected.