The ear performs two functions, hearing and balance, and is one of the most sensitive and delicately made structures in the whole body. It can easily be damaged, so any aches, pains, or feelings of dizziness should be investigated and treated promptly.
Vibrations in the air travel through the wax-lined outer canal of the ear and cause the eardrum to vibrate. This causes three tiny linked bones in the middle ear to vibrate too. The vibrations then pass into a fluid-filled spiral chamber called the cochlea, where they agitate the delicate endings of banks of nerve cells. These unite to form the cochlear nerve, which then becomes part of the auditory nerve, which is connected to the brain. The brain then interprets auditory nerve messages as speech, music, noise, and so on.
Two passages lead from the middle ear. One goes to the mastoid process, a cavity-filled bone which helps with resonance. The other, the eustachian tube, goes to the nose. The eustachian tube ensures that pressure inside and outside the eardrum is equal. If it is not, the eardrum will not vibrate properly. A blocked eustachian tube causes pressure in the middle ear to fall, sucking the eardrum inwards. When the tube unblocks and pressure is equalized, a sudden pop is heard. Catarrh is a frequent cause of eustachian tube blockage.
The inner ear or labyrinth, which contains all the nerve endings responsible for detecting sounds, also contains three semi-circular fluid-filled canals lined with nerve endings which detect movement and acceleration in any plane relative to gravity. The semicircular canals are the organ of balance. As we move, the fluid in them wafts against the nerve endings, stimulating them to send messages to the brain. The brain then integrates these messages with others coming from the eye and from pressure receptors all over the body. |
Back to Ailments & Diseases
