The middle ear is located inside the tympanic bone of the crown. The parts of the middle ear are the eustachian tube, the cochlea and the sphincter.
1. Eustatian Tube: The narrow tube from the tip of the middle ear to the pharynx is called Eustatian tube. It keeps air pressure equal on both sides of the tympanic membrane. It is named after the 16th century Italian physician Bartolommo Eustachio.
2. Ear Ossicles: There are 3 small bones in the middle ear. These are-
(i) Malleus: It looks like a hammer. One end is attached to the tympanic membrane and the other end to the incus
(ii) Incus : It looks like anvil. One end is attached to the malleus and the other end to the stapes
(iii) Stepis: Stepis looks triangular or like the stirrup of a horse saddle. It is the smallest bone in the human body. One end is attached to the incus and the other end to the fenestra ovalis.
Function: Bones conduct sound waves from the tympanic membrane to the cochlea.
3. Opening: There are two openings in the middle ear. Fenestra ovalis (oval window) at the top and fenestra rotanda (round window) at the bottom. Sound enters the cochlea through the fenestra ovalis and exits through the fenestra rotanda.