![]() The Eustachian tube has the function of equilibrating the environmental pressure with inner pressure, protecting the middle ear from abrupt pressure changes. Keywords: valsalva maneuver, tympanic membrane, eustachian tube. Renata Rumy Makibara 1, Jackeline Yumi Fukunaga 2, Daniela Gil 3 MuscleEustachian tube function in adults with intact tympanic membrane It also has an active opening mechanism - this is mediated by four muscles surrounding the tube. Fig 3 - The opening of the Eustachian tube into the nasopharynx, posterior to the inferior concha. The cartilaginous part is incomplete along the lower and lateral margin of the tube, and is completed by fibrous tissue - the membranous lamina. Note the proximity of the internal carotid artery to the auditory orifice, Osseous Portion Fig 2 - The osseous and cartilaginous parts of the Eustachian tube. The epithelial lining of the Eustachian tube surrounding the tympanic orifice is ciliated columnar with goblet cells. The internal carotid artery is closely associated with the medial wall of the Eustachian tube at the tympanic orifice, where the overlying bone may be thin or even dehiscent in approximately 2% of the cases. Anterolateral to this opening is Huguier’s canal - where the chorda tympani nerve leaves the middle ear. It is located just above the middle ear floor. The tympanic orifice of the Eustachian tube marks the opening of the tube into the middle ear. It contains a tympanic and a pharyngeal orifice and is divided into an osseous and cartilaginous portions. The Eustachian tube arises from the anterior wall of the middle ear and slopes downward, forward, and medially to reach the nasopharynx. Fig 1 - The Eustachian tube connects the tympanic cavity to the nasopharynx Parts of the Eustachian Tube Main action is as part of the acoustic reflex, but a secondary action is to open the Eustachian tube.It is attached to the cartilaginous portion of the Eustachian tube. Muscle of the pharynx that is also attached to the pharyngeal orifice of the Eustachian tube and contributes to tube opening. ![]() Attached to the pharyngeal orifice of the Eustachian tube and is thought to make a minor contribution to tube opening.Acts to elevate the soft palate during swallowing.Innervated by the mandibular nerve (branch of the trigeminal nerve).Makes the largest contribution to active opening of the tube.Attached to the lateral wall of the Eustachian tube, and so can open the tube with each contraction.Acts to tense the soft palate during swallowing and yawning.It also has an active opening mechanism – this is mediated by four muscles surrounding the tube. The Eustachian tube is able to passively open when there is a postive pressure difference between the nasopharynx and middle ear (letting air enter or exit). The epithelial lining of the tube near the tympanic orifice is ciliated pseudostratified with goblet cells. It is located posteriorly to the inferior concha of the nasal cavity. The pharyngeal orifice marks the opening of the Eustachian tube into the nasopharynx. The cartilaginous part is incomplete along the lower and lateral margin of the tube, and is completed by fibrous tissue – the membranous lamina. It lies in a groove between the petrous part of the temporal bone and the greater wing of the sphenoid bone (petrosphenoidal fissure). The cartilaginous portion refers to the two-thirds of the Eustachian tube nearest to the nasopharynx. It has a serrated margin for attachment of the cartilaginous component of the tube. The distal end of the osseous portion is formed by the petrous part of the temporal bone. It can be variably surrounded by peritubal air cells.Īlong the roof of the osseous part of the Eustachian tube is a canal containing the tensor tympani muscle. ![]() The osseous portion refers to the third of the Eustachian tube nearest to the middle ear. Adobe Stock, Licensed to TeachMeSeries Ltdįig 2 – The osseous and cartilaginous parts of the Eustachian tube.
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