Middle Ear
Studies on the Human Ear

The Middle Ear

The middle ear is located between the outer ear and the inner ear and is comprised of the eardrum, the ossicular chain which includes the hammer, anvil and stirrup, the middle ear cavity, and the oval window.

The eardrum is a thin fibrous membrane, similar to a small drum head. The eardrum separates the auditory canal of the outer ear from the cavity of the middle ear. The buried and protected position of the eardrum makes it nearly independent of the effects of temperature and humidity, and protects it from accidental damage.

The hammer, anvil and stirrup form a flexible chain of three small bones which extend across the middle ear cavity, from the eardrum to the oval window. The handle of the hammer is connected to the eardrum by thin fibers. The anvil rests between the hammer and the stirrup. While the foot of the stirrup is attached directly to the oval window. All three bones are held in place by muscles and ligaments.

The middle ear cavity is formed along the boundaries of the outer and inner ear. The upper end of the cavity contains the hammer, anvil, and stirrup, while the lower end forms a small pocket of air which extends downward from the mouth of the Eustachian tube. The entire middle ear cavity is about a third of an inch wide and a sixth of an inch deep.

The oval window is a thin oval-shaped membrane which covers a small opening at the base of the cochlea. The oval window separates the interior wall of the middle ear cavity from the inner ear.

The function of the middle ear is to detect sounds which have been trapped by the outer ear, to amplify them, and transmit them to the inner ear.

The middle ear is uniquely designed to amplify incoming sounds so that they are able to penetrate the dense liquid medium of the inner ear. In addition, there are two sets of middle ear muscles which act as a reflex system to protect the inner ear against loud noises.

All of the middle ear functions occur within a space approximately the size of a sugar cube.