Question

Briefly explain the structure of the ear.

Answer 1

Ear is an hearing organ in mammals which develops from a pharyngeal pouch and it consists of mainly three parts- outer ear, middle ear and inner ear.

Complete answer:
The ear mainly consists of three parts which are external, middle and inner.
1. External ear: External or outer ear consists of three parts which includes- Pinna, ear canal and outer layer of ear drum. Pinna is a funnel-shaped structure and it is made up of rigid cartilage which is covered by skin. The main function of pinna is to focus on the sound waves. Pinna opens into the ear canal and the skin which surrounds the ear canal contains sebaceous glands that produce ear wax and this ear canal ends at the outer layer of ear drum. Eardrum separates the outer and middle ear as shown in the diagram.
2. Middle ear: Since it's middle ear, it lies between the outer and inner layer which consists of a tympanic cavity and three ossicles. If you look at the diagram, there are ossicles which are three specialized bones- malleus, incus and stapes and ossicles transmit sound vibration from the eardrum to the oval window. Malleus receives vibrations from sound pressure to the eardrum and then it is transmitted to incus which is then transmitted to stapes. Stapes vibrate and then these vibrations are transmitted to the oval window.
3. Inner ear: Inner ear consists of vestibular organs and the cochlea as shown in the diagram. Cochlea is the organ of hearing which is a spiral shell-shaped structure and cochlea is responsible for the sense of hearing. This cochlea is divided into three fluid-filled spaces which are vestibular duct, cochlear duct and tympanic duct. The sound waves are transmitted to the vestibulocochlear nerve in the inner ear.

Note: Since there are three parts of ear, sound waves are first received by the outer ear which are then modulated to the middle ear and then further from the middle ear, it passes to the inner ear and then the nerve transmits the information to the brain where it is known to be sound. The pinna helps to focus the sound which impacts on the eardrum.