Q1. Briefly describe the structure of the following:
Ear: Ear is the sense organ for hearing and equilibrium. It consists of three portions external ear, middle ear, and internal ear.
1. External ear: It consists of the pinna, external auditory meatus, and a tympanic membrane. Pinna is a sensitive structure that collects and directs the vibrations into the ear to produce sound. External auditory meatus is a tubular passage supported by cartilage in the external ear. The tympanic membrane is a thin membrane that lies close to the auditory canal. It separates the middle ear from the external ear.
2. Middle ear: It is an air-filled tympanic cavity that is connected with pharynx through the eustachian tube. The eustachian tube helps to equalize air pressure in both sides of the tympanic membrane. The middle ear contains a flexible chain of three middle bones called ear ossicles. The three ear ossicles are malleus, incus, and stapes that are attached to each other.
3. Internal ear: It is also known as the labyrinth. The labyrinth is divided into the bony labyrinth and a membranous labyrinth. The bony labyrinth is filled with perilymph while a membranous labyrinth is filled with endolymph.
The membranous labyrinth is divided into 2 parts.