Structure Of The Ear

Anatomically, the ear has three distinguishable parts: the outer, middle, and inner ear. In this section, we take a general look at the three parts of ear.

The Outer Ear

1. Pinna 2. Auditory Canal 3. Eardrum
The outer ear consists of pinna or auricle, the external auditory canal and the eardrum (tympanic membrane). The outer ear transmits sound to the eardrum. It is made up of cartilage and skin When these sound vibrations reach the eardrum, the eardrum begins to vibrate.

The Middle Ear

1. Eardrum 2. Malleus 3. Incus 4. Stapes
The space inside the ear drum is called the middle ear. Three of the smallest bones of the body are seen in the middle ear. They are called the malleus, the incus and the stapes. These bones are known as the hammer, anvil and stirrup either.The medical term for all three bones together is the middle ear ossicles, that are connected to form the “ossicular chain”.
The last bone in the chain is pushed in and out of the oval window of the cochlea. The eustachian tube, which equalizes pressure between the ear and the environment, is also seen in the middle ear.

The Inner Ear

1. Cochlea 2. Auditory Nerve

The inner ear is the innermost part of the ear that plays an important role in hearing and balance. The inner ear consists of tiny bony structures filled with fluid. As sound waves travel from the outer to the inner ear, they create waves in the fluid of the inner ear, which in turn moves the tiny hairs in the ear that send sound or movement signals to the brain.

Problems with this part of the ear can result in hearing loss and balance issues. Inner ear problems are one of the primary causes of vertigo.

The rocking motion of the stapes in the oval window moves fluid within the cochlea causing a “shearing” action or movement of the hair cells. This shearing action causes the hair cells to send an electrical impulse to the auditory nerve.

Retro-Cochlear Auditory Pathway

The auditory nerve carries the information to the brain, via the brainstem, for decoding. There are auditory centers in the brain which interpret the stimulus enabling the understanding of what is being heard. If these parts of the brain are badly damaged or are not stimulated for a long period of time, a patient may not be able to hear speech even at high levels despite the fact that the auditory nerve has transmitted it to the brain.

If these parts of the brain are badly damaged or are not stimulated for a long period of time, a patient may not be able to hear speech even at high levels despite the fact that the auditory nerve has transmitted it to the brain.

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