Question

Describe the internal structure of the human ear with a labelled diagram.

Answer 1

Hint:Humans have five sense organs. One of the sense organs is the ear. It enables us to receive the sound and hear our surroundings. It consists of bones and cartilages. The internal structure of the human ear is divided into three parts- external ear, middle ear and inner ear.

Complete answer:
The human ear is one of the most important sense organs in the human body which enables us to detect and transmit the various sounds. It also helps in maintaining the sense of balance of the body. The three main parts of the human ear include- external ear, middle ear and inner ear.
External ear:
>It consists of auricle, external auditory meatus and tympanic membrane.
>Auricle is also called the pinna which is made up of thin cartilage which is elastic in nature. It is covered by skin. The main function of this part is to receive the sound waves and pass it on to the middle ear. The ear lobule present in the pinna consists of adipose and fibrous tissues.
>Pinna is followed by a slightly covered canal which consists of bone in the inner side and cartilage on the outer side. This part of the ear consists of various wax glands.
>Tympanic membrane plays an important function by amplification of sound. It separates the inner and external ear.
Middle ear:
>It consists of a tympanic cavity, eustachian tube and ear ossicles.
>The tympanic cavity is lined by a tympanic membrane on one side and a bony wall on the other side. It is a narrow fluid filled irregular space. It consists of two openings- round and oval window.
>A narrow tube of about 4 cm long is present from the tympanic cavity to the nasopharynx. It is called an eustachian tube. The main function of this part is to maintain equal air pressure on both sides of the tympanic membrane.
>The three bones forming a lever from the tympanic membrane to the inner membranes are called ear ossicles. They are malleus, incus and stapes. The hammer shaped bone which is in contact with the tympanic membrane is called as malleus, the middle anvil shaped bone is called as incus and the smallest bone in the human body is the stapes which articulates with the incus on one side and oval window on the other side.
Inner ear:
>The inner ear is also called a labyrinth. It contains two types: bony and membranous labyrinth.
>The membranous labyrinth is surrounded by a fluid inside the perilymph which is present inside the bony labyrinth.
>The bony labyrinth consists of a vestibule, semicircular canal and cochlea. Cochlea is the main hearing organ.

Note:The pinna collects the sound waves which pass through the auditory canal to reach the eardrum. The sound waves cause the eardrum to vibrate and get converted to mechanical vibrations. These vibrations pass to the ear ossicles and get amplified. These vibrations cause vibration in the fluid of cochlea. The stimulation of sensory cells produces electrical signals which reach the nerves.