11. It has been estimated that about 30 % of people with Meniere's disease have eustachian tube dysfunction. 12. Major causes are ear infections or conditions that block the eustachian tube , such as allergies or tumors. 13. The Eustachian tubes , passages that connect the middle ear with the pharynx, are very complex in crocodilians. 14. In fact, the eustachian tubes are not located close enough to the mandible to be pinched off. 15. The Eustachian tube , which opens near the velopharyngeal sphincter, connects the middle ear and middle ear infections. 16. The Eustachian tube connects from the chamber of the middle ear to the back of the nasopharynx. 17. Normally, the Eustachian tube is collapsed, but it gapes open both with swallowing and with positive pressure. 18. The eustachian tubes help the ear to drain and balance pressure on the inner and outer ear. 19. You also get a similar effect by yawning, since the yawning mechnaism also involves the eustachian tubes . 20. But during a steep descent, pressure that builds up outside the body can push the eustachian tube closed.
