How do we hear?


The ear consists of three major parts: the outer ear, the middle ear and the inner ear. The outer ear includes the pinna (the visible part of the ear) and the ear canal. The outer ear extends to the tympanic membrane (eardrum), which separates the outer ear from the middle ear. The middle ear is an air-filled space located behind the eardrum. It contains 3 tiny bones, the malleus, incus and stapes, which transmit sound from the middle ear to the inner ear. The middle ear is connected to the back of the nose and upper throat by the Eustachian tube. This tube ventilates the ear and equalizes the air pressure in the middle ear to the outside air pressure. The inner ear contains the hearing (cochlea) and balance (labyrinth) organs. The auditory nerve connects the cochlea to the brain.

In a healthy ear, sound waves striking the eardrum send vibrations through the 3 tiny bones in the middle ear. Movement of these bones transmits sound waves across the middle ear to the cochlea of the inner ear. In the cochlea, sound is transformed into nerve impulses that travel to the brain. In this manner, sound is perceived.


What is Otitis Media?


Otitis Media is an infection or inflammation of the middle ear that usually follows a buildup of fluid in the middle ear space. This condition occurs when the Eustachian tube becomes inflamed following a cold, sinus or throat infection, allergic reaction, or is blocked by enlarged adenoid tissue. Fluid accumulating in the middle ear cannot drain properly and may become infected. Bacteria are the primary causes of otitis media and are detected in 70% of cases. The most common microorganisms detected are Haemophilus influenzae and Streptococcus pneumoniae. Less common bacteria involved are Moraxella catarrhalis and Streptococcus pyogenes. Viruses are not usually a direct cause of otitis media, but play a major role by causing inflammation in the nasal passages and impairing defense systems, such as cilia, in the ear. Respiratory syncytial virus (RSV), Influenza virus and Rhinovirus are the prime suspects. Although this condition occurs most often in children one to three years of age, older children and adults may develop it as well.