The tympanic membrane is also known as the eardrum. It consists of a very thin layer of skin which lies at the end of the ear canal and marks the boundary between the middle ear and the outer ear. It vibrates with sound energy and transmits this vibration to the ossicles. These are tiny bones which amplify the sound energy to make it more readily detected by the sensory apparatus of the ear.
Equalisation of the pressure on both sides of the eardrum allows the drum to remain compliant. This means it can vibrate as much as possible in response to sound energy. The Eustachian tube allows this to happen by connecting the middle ear space to the nasal cavity. If this becomes blocked or is unable to open for some reason, then the pressure is not equalised. Hearing is dulled, and it is possible for the drum to rupture.
This can happen under several circumstances; one of the most common is in infection. Otitis media can result in the formation of pus. This creates pressure behind the eardrum which can result in it bursting. The cardinal sign is increasing pain followed by relief and a rush of pus and blood from the ear. The causes of a ruptured eardrum includes a high pressure wave such as that which occurs with a bomb blast or a lorry tire exploding right by the ear. As well as this the changes of pressure which are experienced during scuba diving and a plane travel can also results in rupture.