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If you are reading this article, chances are you want to understand more about the human ear.
You may have read in several articles and heard several people say things like “I have a middle ear infection”, “Apparently my inner ears are damaged”, “the doctor said it is a nerve issue and not because of wax or infection”. What exactly could all this mean? What does it mean when your doctor says you have a problem in the inner ear? Are inner ear and nerve the same?
If you have ever thought about these things, you are in the right place!
Our ears are marvelous structures that not just help us to hear, but also help our body maintain its balance.
The human ear is divided into 3 major parts: Outer Ear, Middle Ear and the Inner Ear.
Outer Ear:
This - like the name suggests - is the outermost part of our ear. This part is visible to us.
It comprises of 2 structures called
Pinna
External Auditory Canal (EAC)
Pinna is basically the part that we most commonly call the ‘ear’.
Pinna and the EAC help in funneling the sounds into the ear.
Did you know that each groove and ridge in our pinna has been evolved specifically in a way to funnel specific frequencies. This happens because the resonant frequencies are altered based on the structure of the medium.
EAC also helps in trapping foreign objects through hair and ear wax present in EAC, thereby preventing any damage to the eardrum.
Middle Ear:
For the ease of imagination, the middle ear is like a room filled with air. It has six walls and 3 tiny bones, known as the middle ear ossicles. Its outermost wall is formed by the eardrum, near the cochlea, formed by the footplate of stapes connected to another membrane called oval window.
Did you know that Stapes (meaning: stirrup) is the smallest bone in the body?
The middle ear is also connected to a part of our nose/throat through a tube called the Eustachian tube. The tube helps in equalizing the air pressure between the inside and outside of your middle ear. This is why you feel that your ears pop while flying on an airplane. Interesting, isn’t it?
When we have a cold, the middle ear could be filled with fluid, and eventually result in a middle ear infection. This can disrupt the conduction of sound to the inner ear and result in hearing loss. Similarly, when wax is impacted in our ear canal or when there is an infection in our outer ear, it can affect the conduction of sound into the inner ear and result in hearing loss.
Redundantly enough, this type of hearing loss is called Conductive Hearing loss. This can be most commonly treated by medicines or surgery.
Inner ear:
This is the innermost part of our ear (duhhhh!)
It is also the part of the ear that is the main site of hearing. It has sensory cells and also comprises the auditory nerve.
In general, inner ear is mainly divided as:
Cochlea
Vestibular system
Vestibulocochlear nerve
The cochlea houses the sensory cells responsible for the hearing. These sensory cells are lakhs of tiny little hair like structures called the hair cells.
The movement of hair cells results in generation of neural impulses in the auditory nerve (a part of vestibulocochlear nerve).
The vestibular system is mainly responsible for maintaining the balance of the body. It is an intricate system that requires a blog post of its own, so more about that later!
The vestibulocochlear nerve is a nerve that is connected to the cochlea and the vestibular system. It transmits the information to the auditory region in the brain.
When there is a problem in the inner ear such as damage or degeneration of the hair cells, build up of inner ear fluid, or degeneration of the auditory nerve among others, it can hamper the perception of sound.
This is called a sensorineural hearing loss. When the hearing loss is caused purely due to a problem in the cochlea, it is called a sensory hearing loss. Similarly, if the hearing loss is purely caused due to a problem in the auditory nerve, it is called a neural hearing loss. In most forms of sensorineural hearing losses, both cochlea and the nerve are affected. Unless specialised tests are carried out, it is quite difficult to specifically find out how much problem exists in the cochlea and how much in the nerve. Hence, the diagnosis is almost always made as sensorineural hearing loss.
Sensorineural hearing loss usually cannot be reversed and medicines are futile in most cases. The best way to address this type of problem is by wearing hearing aids or cochlear implants.
A problem in both outer and/or middle ear and the inner ear results in mixed hearing loss.
In summary,
Ear is divided into three parts: outer, middle and inner ear.
Problems in the outer and/or middle ear result in conductive hearing loss and can usually be treated by medicines or bone conduction devices such as bone anchored hearing aids or bone conduction implants.
Problems in the inner ear can result in sensorineural hearing loss and can be addressed by wearing hearing aids or cochlear implants.
Is it not amazing how wonderful our ears are? They are such intricate systems, formed by millions of years of evolution and understood after decades of research yet, the knowledge we have just about our cochlea is like a tip of the iceberg! Having such beautiful structures in our body, we tend to neglect taking care of our ears very frequently. We take our hearing for granted!
Now that you know what your ears are and what kind of hearing loss they can lead to, you can also educate others about this and make hearing care more acceptable and common. 🙂
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