The human ear is a hearing organ designed to collect sound vibrations, and then pass those vibrations to the brain through auditory nerves. The main part of the ear is located inside the skull. The ear has a complex structure; it has several small bones intricately arranged inside it. It has the smallest bone of the body, the stapes. The sound waves from the outer ear travel to the middle ear. Through the bones and ear-drum, it travels to the innermost part, the bony labyrinth.
The external ear
The external ear, also called the auricle or pinna, is divided into the following parts: the pinna and external auditory meatus. It is a funnel that collects the sound vibrations. The collected sound vibrations travel through a large membrane present at the end of the external ear. The irregularly shaped auricle is made up of cartilage and fibrous tissues. The narrow entrance of the ear is called the concha. The ear canal has wax and hair to trap dirt that could harm the internal ear.
Ear Drum
The ear-drum is a thin membrane present at the interface of the outer ear and the middle ear. This membrane acts as a drum, which is beaten by sound waves. It is connected with a set of three small bones. It is an important as well as a crucial part of the ear which helps a human being to hear. When the ear-drum receives a sound, it vibrates to and fro. These vibrations are received by the auditory nerves and are eventually transferred to the brain as signals.
Middle Ear
The middle ear is the connection between the external ear and the inner ear. The ear-drum is placed at the entrance of the middle ear. The middle ear has ear bones (ossicles) which act as small levers that work together to relay the sound vibration. These bones are: malleus, incus and stapes. At the end of the bones is the tympanic cavity and eustachian tube. This tube regulates air pressure in the ear.
Eustachian Tube
Eustachian tube, also called the auditory tube, is a narrow tube that connects middle ear to the throat. It is an important part of the human ear. This tube balances the pressure of the air on both sides of the ear-drum. This equilibrium can be disturbed by the sudden changes in air pressure that can be experienced while diving underwater or while travelling in aircraft. Another important task performed by this tube is that it drains the mucus towards the throat. Mucus is produced by the lining of the middle ear.
Cochlea
Cochlea is the main part of the inner ear. It resembles a snail’s shell. The cochlea is filled with a liquid and lined with many nerve cells. It is designed to receive the sound vibrations. When the eardrum vibrates, the vibrations are, in turn, passed along the three small bones of the middle ear. The last bone of the middle ear is set into the cochlea, so the vibrations cause the liquid in the cochlea to move and sweep over the nerve cells, which send signals to the brain along the auditory nerve.
Inner Ear
The innermost part of the ear is the inner ear. The main parts of the inner ear are the oval window and the bony labyrinth. The bony labyrinth is further divided into three parts: the vestibule, the cochlea and the semi-circular canals. The inner ear is filled with a liquid. The cochlea is the most important part as it converts sound vibrations into nerve signals. The internal ear is innervated with auditory nerves.
Head Balancing Fluid in the Ear
The innermost semi-circular canals of the ear have fluid in it. This fluid is very important for balancing the position and movement of the head. This fluid moves when our head moves or rotates. The movement of the fluid sends signals to the brain about the direction and speed of the rotation of the head. When we spin our head continuously for a few minutes and suddenly stop, we feel dizzy. This is because when the head is spun fast, the fluid in the canals also starts moving and sustains the movement even after the head has stopped its movement. The movement of the fluid sends signal to the brain about the spinning of the head. This, in turn, confuses the brain, because the head has stopped rotating but the ear fluid is sending signals regarding the rotations. As a result, we start feeling dizzy.
