The three parts of the ear are the outer ear, the middle ear and the inner ear.
The outer ear and the middle ear serve only for hearing, the inner ear serves for hearing and balance.
The outer ear consists of the auricle and auditory canal. The auricle is the external and visible part of the ear, it is made of cartilage covered entirely of skin. The auditory canal begins at the center of the auricle on the outside, it is a short, narrow tube. It is 2 to 3 cm long and about 0.5 cm wide, it is closed inside by ear-drum. The ear-drum is thus at the end of the auditory canal and marks the beginning of the middle ear.
The middle ear is a set of small cavities filled with air dug in the temporal bone. It consists of the ear-drum, the ossicles (hammer, anvil, stirrup) and the Eustachian tube. It begins with the ear-drum, it is an extremely thin membrane that measures 8 to 10 mm thick with a surface of about 60 mm², stretched by small muscles. Its central cavity is the tympanic case, it is the auditory element of the middle ear, it is dug in the temporal bone, it is filled with air and communicates with the Eustachian tube. The tympanic case begins at the ear-drum and marks the end of the middle ear. At the ear-drum are connected the ossicles, they are bones, the names of the ossicles evoke their form: hammer, anvil, stirrup. The ear-drum is mechanically connected to the inner ear by the ossicles, the stirrup resting on the vestibule window, which constitutes the beginning of the inner ear. The Eustachian tube is an oblique conduit that connects the middle ear to the throat.
The inner ear is located in the temporal bone. It is composed of two structural parts: a bony part of protection, called the bone labyrinth (semicircular canals, vestibule of the bone labyrinth, cochlea), and a sensory part, called the membranous labyrinth. The bone labyrinth constitutes a bone hull around the membranous labyrinth. The membranous labyrinth is the set of cavities that supports the sensory elements of the inner ear. All the structures of the inner ear thus have a bone part and a membranous part. The membranous labyrinth is subdivided into two parts: an anterior part (cochlear canal) and a posterior part composed of the utricle, the saccule, and the semicircular canals. It contains endolymph. The cochlea is the organ of hearing. The vestibule is lodged between the cochlea and the semicircular canals, and forms part of the organ of equilibrium. Other elements are the window of the vestibule = oval window that marks the beginning of the vestibule, the cochlea and the window of the cochlea = round window that marks the end of the cochlea.