Sense Organs : Parts and Functions of Ears

Ears are one of the five sense organs. Ears are helpful for listening.

Transmission of Sound Waves:

Sound waves are received by the outer ear and they are conducted to specialized receptor cells within the ear and they are transmitted by those cells to the nerve fibers that lead to the auditory region of the brain in the cerebral cortex. The sensations of the sound are perceived within the nerve fibers of the cerebral cortex.

Pinna —> External Auditory Canal —-> Tympanic Membrane —-> Malleus —-> Incus —-> Stapes —-> Oval window —> Auditory nerve fiber —> Cerebral Cortex.

EAR -external,middle,inner

Parts or regions of the Ear:

The ear can be divided into three separate regions, namely

1. Outer Ear
2. Middle Ear
3. Inner Ear

Parts and Functions of the Outer Ear :

Sound waves enter the ear through the pinna, which is the projecting part or flap of the ear. The external auditory meatus leads from the pinna and is lined with numerous glands that secrete a yellowish brown colored waxy substance called as cerumen. The function of the cerumen is to lubricate and protect the ear.

Parts and Functions of the Middle Ear :

Sound waves travels through the auditory canal and strike a membrane between the outer and middle ear, this is known as tympanic membrane or ear drum. As the ear drum vibrates, it moves three small bones that conduct the sound waves through the middle ear. These bones in the order of their vibration are malleus, the incus and the stapes. Stapes is the smallest bone  in the human body. As the stapes moves it touches a membrane called the oval window, which separates the middle ear from the inner ear. The auditory tube or eustachian tube is a canal leading from the middle ear to the pharynx. This tube can prevent damage to the ear drum and shock to the middle ear and inner ears.

Parts and Functions of the Inner Ear :

Sound vibrations  having been transmitted by the movement of the ear drum by the bones of the middle ear reach the inner ear via the fluctuations of the oval window that separates middle and inner ears. The inner ear is also called labyrinth because of its circular maze like structure.

The part of the labyrinth that leads from the oval window is a bony snail shaped structure called as the cochlea. The cochlea contains special fluids called as perilymph and endolymph, through which the vibrations travel. Also present in the cochlea , a sensitive auditory receptor area called as the organ of corti.

In the organ of corti, tiny hair cells receive vibrations from the auditory liquids and relay the sound waves to the auditory meatus.

The ear is an important organ for maintaining the equilibrium as well as an organ for hearing. The vestibule connects the cochlea to 3 semicircular canals for balance. The semicircular canals contains a fluid called endolymph and sensitive hair cells in an intricate manner. The fluid and hair cells fluctuate inresponse to the movement of the head.