Eustachian tube ear function12/25/2023 Its strength declines with age and a change in its force vector and a reduction in its range of motion. The medial segment is derived from the middle third of the posteromedial wall of the tube that is mostly cartilage the two segments then migrate inferiorly and converge on the pterygoid hamulus forming a strong tendon that curves around the hamulus and anchors directly into the soft palate as the palatine aponeurosis. The TVP operates in combination with the tensor tympani muscle (TT), and they both share similar nerve innervation. Its lateral surface directly contacts the surface of the anterior superior medial pterygoid muscle. The TVP is made of an external and medial portion, the first of which originates from the navicular fossa, the lateral aspect of the sphenoid bone/sulcus, and the tensor tympani muscle. During these motions, the ET is oriented inwards. The tensor muscle of the soft palate (TVP) not only functions to open up the lumen of the Eustachian tube, but it also contributes to mastication as it is actively involved in the process of phonation, swallowing, chewing. There are 6 muscles recognized as having an active role in the functions of the tube: tensor tympani, salpingopharyngeus tensor veli palatini levator veli palatini lateral and medial pterygoids. The discontinuous opening of the pharyngeal ostium in the nasopharynx causes peristaltic-like movements that may be due to the visco-elastic features of the tubular structure of the cartilage. It then proceeds forward, downward, and medially, to form a 45-degree angle to the sagittal plane, and about a 30-degree angle to the horizontal plane. The Eustachian tube is located in the para-pharyngeal space and is closely linked to the infratemporal fossa. The Eustachian tube continues from the front wall of the middle ear to the sidewall of the nasopharynx, progressing along the posterior edge of the medial pterygoid plate. The active opening of the Eustachian tube to relieve positive or negative pressure in the middle ear commonly is called “clearing the ear.” These can be actively pulled apart to open the tube with the help of accessory muscles or passively pushed apart by air exiting or entering the middle ear under pressure. Partly a hollow tube in bone and partly a potential space in fibroelastic cartilage, the Eustachian tube is normally closed, as its proximal walls are collapsed. Patency of the tube allows for air exchange in the tympanic cavity to replenish oxygen to the middle ear, in addition to providing an outlet for mucus and other fluid from the middle ear. It is believed that the Eustachian tube also may be involved in sound transformation through reverberation phenomena. It thus influences the tension in this structure and the attached ossicles, and in this way indirectly affects the effectiveness of sound wave transmission. In doing so, the Eustachian tube allows for regulation of the pressure across the tympanic membrane. More specifically, the Eustachian tube permits equalization of pressure in the middle ear with respect to ambient pressure. The Eustachian tube plays a role in equalization, oxygenation, and drainage of the tympanic cavity in the middle ear.
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