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.
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