Tympanic cavity

The tympanic cavity, also known as the middle ear, is a small, air-filled chamber located within the temporal bone of the skull. It serves as a vital link between the external environment and the inner ear, allowing for the transmission of sound waves from the outer ear to the auditory system.

Structure

The tympanic cavity is a complex, three-dimensional space that is bounded by the temporal bone of the skull and the lateral wall of the pharynx.^[5] It consists of three main parts: the pars tensa, pars flaccida, and the attic.

Pars Tensa

The pars tensa is the most posterior and largest part of the tympanic cavity.^[3] It is a thin, membrane-like structure that is attached to the lateral wall of the middle ear and extends from the oval window to the round window. The pars tensa is composed of connective tissue and contains the tensor tympani muscle, which helps to dampen the vibrations of the ossicles.

Pars Flaccida

The pars flaccida is the anterior and smaller part of the tympanic cavity. It is located between the pars tensa and the attic and is composed of a thin layer of connective tissue. The pars flaccida is responsible for transmitting sound waves from the external auditory canal to the ossicles.

Attic

The attic is the superior part of the tympanic cavity and is located above the pars tensa.^[1] It is a small, triangular-shaped space that is bounded by the tegmen tympani, the lateral wall of the middle ear, and the promontory. The attic contains the auditory tube, which connects the tympanic cavity to the pharynx and helps to equalize pressure between the middle and outer ear.

Location

The tympanic cavity is located within the temporal bone of the skull, which is located on the lateral aspect of the head.^[2] It is situated behind the external auditory canal and is separated from the external environment by the tympanic membrane, also known as the eardrum. It is connected to the inner ear via the oval window and the round window, which are small, membranous openings located in the bony walls of the middle ear.

Function

The main function of the tympanic cavity is to transmit sound waves from the external environment to the inner ear. ^[4]This process occurs through a series of bones and muscles known as the ossicular chain, which consists of the malleus, incus, and stapes. When sound waves enter the external auditory canal, they strike the tympanic membrane and cause it to vibrate.^[6] These vibrations are then transmitted through the ossicular chain to the oval window, which is connected to the cochlea of the inner ear. The cochlea contains thousands of hair cells that are responsible for converting the vibrations into electrical signals, which are then transmitted to the auditory nerve and sent to the brain for processing. In addition to its role in sound transmission, the tympanic cavity also serves to protect the inner ear from foreign objects and to regulate the pressure within the middle ear. The auditory tube connects the tympanic cavity to the pharynx and helps to equalize pressure between the middle and outer ear. This is important because changes in atmospheric pressure can affect the functioning of the inner ear and cause discomfort or hearing difficulties.^[8]