Structure of an Ear

Structure of an Ear

Ear is the organ and that part of the body which helps human being to hear and balance. The ear is divided into three pats. It has an external part that is connected with the middle part and finally the inner part. The outer portion of the ear has been named as pinna. This part is built with ridged cartilage and is protected by the skin which covers the inner parts of the ear from getting damaged from external source. Sound travels through the route of the pinna which traverses into the auditory canal that is present at the external part. The canal is a tiny tube which terminates at the point of meeting eardrum which is scientifically known as tympanic membrane. 

External ear  

Pinna: The external part of the ear consists of two different parts.  Pinna is also known as auricle. The entire external part is known as Pinna.

External auditory canal or tube: This is a small tube that acts as a bridge to connect one part of the ear to the other. The outer ear is connected with the middle ear by this tiny tube which is known as the external auditory canal or tube.

Tympanic membrane: This does not function as the external auditory canal rather it acts in the complete opposite way. The function of the external auditory canal is to connect the outside of the ear to the inside of the ear while the tympanic membrane divides outside of the ear from the middle part of the ear. The tympanic membrane is also known as eardrum.

Middle ear

Ossicles: There is a point where three of the small bones are placed one after the other. This is called ossicles. The bones are connected with each other to send out the sound waves from the external ear to the inner ear. The three bones are respectively malleus, incus and stapes. Stapes is the smallest bone in the human body. The entire middle ear is known as tympanic cavity. 

Eustachian tube: There is a point where a part of the ear is connected with the back part of the nose. The tube which connects the gap between the middle ear and the back part of the nose is known as Eustachian tube. The tube not only connects the middle ear with the nose but also helps in equalize the constant pressure that passes to the middle ear. The pressure is needed to be equalized because it helps in transferring the sound waves in a proper way. The tube acts as the connecting line which is merged with mucous the way the nose and the throat is lined together.

Inner ear

Inner ear is made up of three different parts.

Cochlea: This part is responsible for containing the nerves that help humans in hearing. The most important part of the inner ear is this for it contributes the most in hearing. This is solely responsible for generating the feeling of hearing. There lies another most important organ which is known as the organ of Corti. This is considered to be really important because it acts as the translator of the sound vibrations and changes them into nerve impulses. These sound impulses are then transmitted to the brain for the functioning of processing. The interpretation of the impulses takes place in the brain too.

The other important part which exists inside the cochlea is the hair cells. With deeper analysis it can be understood that the way a drumstick and the sound impart a great force on the drum at the moment of striking the drum. The hitting of the sound waves in the eardrum impacts similarly. When the eardrum gets vibrated the oval window also starts moving back and forth. That finally leads to displace the fluid which is dropped inside the cochlea causing the sound waves to create an impression of ripple inside it. Hair cells are even tinier parts of organ of Corti which are also responsible for coming into motion because of the movement of the sound wave. They are responsible in transmitting sound into electric impulses.

The nerve fibres that collectively receive the signal which is sent by the hair cells are commonly known as auditory nerves. It carries the electric impulses to the brain for the process of interpretation.

Vestibule: Ear helps in maintaining balance of the human body. This part of the inner ear contains receptors which help in maintaining balance.

Semicircular canals: This is a canal which has different shape than that of the vestibule but functions in the same way. It also contains the receptors that help in maintain balance.

The process of hearing

The whole process of hearing does not only take place inside the inner ear rather it involves all the three parts of the ear to generate sound and regulate the process of hearing. It gets started in the outer ear. When a sound is generated outside the external ear, the sound waves in the form of vibrations is carried through the external auditory canal and travels down the entire route to hit the eardrum that is also known as tympanic membrane. As soon as the sound waves touch the eardrum it vibrates the eardrum immediately. After the eardrum is vibrated, the created vibration is now passed on to the three extremely tiny bones that are present in the middle ear which are collectively known as ossicles. The function of the ossicles is to amplify the generated sound. The bones gather the sound collectively and send the waves inside the inner ear and particularly to the hearing organ. The hearing organ is filled with fluid and is called cochlea.

When the generated sound wave is able to successfully reach the inner part of the ear, they are transformed into impulses which are inevitably electric because it would be easier for the brain to catch the electric impulse. These impulses are now sent to the brain by the auditory nerves. Now the brain functions as translating the electric impulses into sound. The sound that is finally generated in the brain finally comes to a state that stimulates the sense of audibility and human beings are able to hear.