State the main function of the following:
Eustachian tube
Topic: Eustachian tube
Answer
It EQUALISES THE AIR PRESSURE on either side of the eardrum, so that the eardrum can vibrate freely.
The Eustachian tube connects the MIDDLE EAR to the PHARYNX (throat).
WHY EQUALISING MATTERS: a difference in pressure would push the eardrum inward or outward, preventing it from vibrating properly and possibly rupturing it. That is why your ears "pop" in an aeroplane or on a mountain road, and why swallowing or yawning relieves the blocked feeling — both open the tube.
THE OTHER SIDE OF THE COIN: the same passage gives INFECTION a route in. Bacteria from a throat infection can travel up it and infect the middle ear — which is why a sore throat is often followed by earache, and why middle-ear infection is commoner in children, whose tube is shorter and more horizontal.