The pinna is made of cartilage and is so formed as to act as...

The pinna is made of cartilage and is so formed as to act as a receiving antenna in charge of guiding the incoming sound waves towards the ear canal. The ear canal is nearly three centimeters long, and produces wax to prevent the entry of dirt and insects into the ear. The middle ear is separated from the ear canal by the eardrum. The middle ear normally contains air and is connected to the back of the pharynx by the Eustachian tube. There are delicate bones in the middle ear.

When sound waves enter the ear and touch the eardrum, these delicate bones vibrate and transfer these signals to a liquid inside the ear. The hearing cells that are there sense these changes and transmit the information to the brain. In simple terms, that is how we hear. Our hearing ability depends on the position of the source of sound, our physical state, the way we eat, and our age. Anatomy and Physiology of the Ear What is the ear? The ear is the organ of hearing.

The parts of the ear include: External Ear or Outer Ear, consisting of: Pinna or auricle - the outside part of the ear. External auditory canal or tube - the tube that connects the outer ear to the inside or middle ear. Tympanic membrane - also called the eardrum. The tympanic membrane divides the external ear from the middle ear. Middle ear (tympanic cavity), consisting of: A) Ossicles - three small bones that are connected and transmit the sound waves to the inner ear.

The bones are called: malleus,[^4] incus,[^5] stapes.[^6] B) Eustachian tube - a canal that links the middle ear with the throat area. The Eustachian tube helps to equalize the pressure between the outer ear and the middle ear. Having the same pressure allows for the proper transfer of sound waves. The Eustachian tube is lined with mucous, just like the inside of the nose and throat.

Inner ear, consisting of: A) Cochlea (contains the nerves for hearing) B) Vestibule (contains receptors for balance) C) Semicircular canals (contain receptors for balance) How do we hear? Hearing starts with the outer ear. When a sound is made outside the outer ear, the sound waves, or vibrations, travel down the external auditory canal and strike the eardrum (tympanic membrane). The eardrum vibrates. The vibrations are then passed to three tiny bones in the middle ear called the ossicles.

The ossicles amplify the sound. They send the sound waves to the inner ear and into the fluid- filled hearing organ (cochlea).