Question

Name the middle ear ossicles. What is their evolutionary origin?

Answer 1

Hint: Human ear is the organ of hearing and balance. It consists of three parts- external ear, middle ear, inner ear. The middle ear connects the external and internal ear by the help of the three ossicles which are nothing but the bones.

Complete answer:
The eye is a complex structure which receives the sound impulses, converted into vibrations by the help of tympanum and these vibrations are amplified in the middle ear, processed in the inner ear and converted into nerve impulses. The amplification of these vibrations takes place in the middle year by the help of three bones called the malleus, incus and stapes.

Let us discuss the structure of the middle ear.

The middle ear is the part of the ear which lies in between the eardrum and the oval window. It contains an air-filled space which contains three bones- malleus, incus and stapes. These ossicles are named in accordance with their shape : hammer, anvil and stirrup. The eardrum is merged with the malleus which is connected to incus and stapes. The ear ossicles transmit the sound vibrations from the tympanum to the oval window of the cochlea.

In the case of reptiles, there are two bones present which hold the upper and lower law. They are called the articular and the quadrate bone. They are similar to malleus and incus. In the case of the tetrapod, the stapes are present.

Note: The attachment of the tympanum to the malleus smoothens the frequency of the sound. They also reduce the sound pressure. The peak efficiency of sound in the middle ear is about 1KHz.