Eustachi tube
The Eustachi tube (also Eustachiröhre or Eustachi'sche tube ) or ear trumpet ( Latin - anat. Tuba auditiva Eustachii or Tuba pharyngo tympanica ) is a tube about 3.5–4 centimeters long in adults that connects the tympanic cavity with the Connects the nasopharynx (pars nasalis of the pharynx) . In adults, the eustachian tube begins on the anterior wall of the tympanic cavity with the tube opening (ostium tympanicum) . From this opening laterally at the top, the tube runs obliquely towards the medial front and bottom, where it ends like a funnel behind the inferior turbinate with the ostium pharyngeum. It runs through the back of the musculotubary canal and is named after the Italian anatomist Bartolomeo Eustachi , who was the first to describe it .
The ear trumpet occurs in all birds , reptiles and mammals (including humans ). In horses ( Equidae ) and some other odd-toed ungulates - families and the hyrax , it also has an extensive baggy extension, the air bag .
history
A first description around 500 BC Chr. Is Alkmaion attributed to the fact, however, an additional opening suspected in goats to breathe over the ears. Eustachius presented the organ for the first time in 1562 with descriptions and a copper engraving in his work Epistula de auditus organis . For procedures and investigations the eponymous researchers dealt with the tube: Antonio Maria Valsalva , Joseph Toynbee and Adam Politzer , the various details on function and task of the organ examined and presented.
construction
The Eustachi tube ( Tuba auditiva ) consists of a bony part ( pars ossea ) and a cartilaginous part ( pars cartilaginea ). The transition between the cartilaginous and the bony part of the eustachian tube is a narrow point and is known in Latin as isthmus tubae auditivae . The bony portion of the tube lies in the musculotubary canal , which runs as a canal through the temporal bone. Here is often spoke of two channels because of the cranial part Canalis musculotubarius the tensor tympani is. This is separated from the caudally lying Semicanalis tubae auditivae by a thin bone lamella . The bony tube portion is in direct topographical relation to the carotid canal .
function
The task of the Eustachi tube is to ventilate the spaces in the tympanic cavity (both middle ears) and to ensure pressure compensation with the ambient pressure. This counteracts any force on the eardrum. This process is triggered by the M. tensor veli palatini and the M. levator veli palatini , which arise from the auditory tuba . When you contract, both muscles contract and the tubes open. This creates a pressure balance between the two rooms.
This pressure equalization enables v. a. the act of swallowing and yawning , as the pharyngeal outlet of the pharyngotympanic tuba opens, the ostium pharyngicum tubae auditivae . If the air pressure equalization is no longer successful automatically, there is limited or no pressure equalization between the middle ear and the nasopharynx ( tube ventilation disorder ). By closing or holding the mouth and nose and simultaneously attempting to exhale, the pressure in the nasopharynx can be actively increased and the eustachi tube can be passively opened ( Valsalva maneuver ). This enables pressure equalization between the outside air and the middle ear. The same applies to negative pressure: A rapid pressure reduction in the outside air - e.g. B. in an airplane that is climbing - can lead to a painful bulging of the eardrum if the middle ear is not adequately ventilated . A numerical example may clarify the balance of forces with changes in pressure: The ear can convert pressure differences of 20 µ Pa into auditory impressions. In commercial aircraft, the cabin pressure drops by around 20,000 Pa during the journey. By closing your mouth and nose and carefully “pulling” against this resistance, you can equalize the pressure yourself and experience it as a pleasant relaxation of the eardrum. When the pressure rises in descent, pressing the breathing air against the closed breathing openings brings relaxation. This applies accordingly in all situations in which the external pressure changes, i.e. when driving up and down the mountains, during activities under water or when driving through tunnels with non-airtight cabins. However, not too much pressure should be applied, as this could tear the eardrum; as soon as pain develops, the attempt should be stopped. The natural way to support the pressure equalization consists in tensing certain throat muscles ( Musculus tensor veli palatini and Musculus levator veli palatini ), which open the entrance to the Eustachian tube when swallowing and yawning and thereby cause the typical "click" in the ear (this may require practice ).
Another function of the Eustachi tube is to drain secretions from the ear. In diseases of the upper respiratory tract , the eustachian tube, by a swelling of the mucous membranes be narrowed or especially in children as a transport channel for an ascending bacterial infection are used and thus a middle ear infection ( otitis media trigger). In rare cases, viruses or fungi can also be the cause, so that antibiotics do not always have to be the right therapy. If the Eustachian tube is not closed as usual, but remains open, autophony occurs , the loud hearing of one's own voice, and in the worst case, a gaping tube .
Diseases
Diseases of the Eustachian tube are referred to in the broader sense as functional and ventilation disorders, which can manifest themselves in different symptoms. In the case of the gaping tube, there is temporary or permanent patency. Physiologically, it only opens when yawning, swallowing and sneezing in order to equalize pressure between the middle ear and the ambient pressure.
Another disease is obstructive tube dysfunction (tube ventilation disorder) , in which the patency of the Eustachi tube is influenced by various factors. In the worst case, it is completely closed.
development
The Eustachian tube is formed together with the tympanic cavity , the cavity of the middle ear , from the first pharyngeal pouch , the former being created from its distal (outer) part and the Eustachian tube from the proximal (inner) part.
Individual evidence
- ↑ KJ Moll, M. Moll: Anatomie . 18th edition. Urban & Fischer Verlag, Munich 2006, ISBN 978-3-437-41743-6 , pp. 733 .
- ^ Charles Joseph Singer: A short history of anatomy from the Greeks zu Harvey . 2nd Edition. New York / Dover 1957.
- ↑ Bartholomeo Eustachii: Bartholomaei Eustachii… Opuscula anatomica . 1726, urn : nbn: de: hbz: 061: 1-201883 .
- ↑ a b K.J. Moll, M. Moll: Anatomy . 18th edition. Urban & Fischer, Munich 2006, ISBN 978-3-437-41743-6 , pp. 734 .