EUSTACHIAN TUBE AND ITS DISORDERS
2
• Outer ear Middle ear Inner ear
• Three main parts of middle ear (1) Three Ossicle bones: - Malleus(1), Incus(3), Stapes(6) Function)Impedance matching (2) Two muscles - Stapedial muscle(5) - Tensor tympani(9) Function)Protection (3) Eustachian tube(8) Function) Equalizer of air pressure
Middle Ear The Eustachian tube is a part of the middle ear? A.No, it is a part of the inner ear B.No, it isn’t part of the hearing mechanism C.Yes D.I don’t know Senteo Question To set the properties right click and select Senteo Question Object->Properties
Anatomy of the Middle Ear The middle ear, an air-filled cavity, includes the tympanic membrane laterally and the otic capsule medially. The middle ear cleft lies between the two. The middle ear is connected by the eustachian tube to the nasopharynx and is continuous with air-filled cells in the adjacent mastoid portion of the temporal bone. The eustachian tube, which is approximately 1 mm wide and 35 mm long, connects the middle ear to the nasopharynx. Normally, the eustachian tube is closed, but it opens by action of the tensor veli palatini muscle when the person performs a Valsalva maneuver, yawns, or swallows. It drains normal and abnormal secretions of the middle ear and equalizes pressure in the middle ear with that of the atmosphere. 6
Eustachian Tube • The eustachian tube connects the front wall of the middle ear with the nasopharynx • The eustachian tube also operates like a valve, which opens during swallowing and yawning – This equalizes the pressure on either side of the eardrum, which is necessary for optimal hearing. – Without this function, a difference between the static pressure in the middle ear and the outside pressure may develop, causing the eardrum to displace inward or outward • This reduces the efficiency of the middle ear and less acoustic energy will be transmitted to the inner ear
The Eustachian tube: A. Opens when one yawns B. Opens when one smiles C. Opens when one blinks D. It is always open E. Never opens Senteo Question To set the properties right click and select Senteo Question Object->Properties
middle ear ➢tympanic cavity ➢tympanic antrum ➢mastoid rocess ➢pharyngotympanic tube
颈内动脉管 internal carotid artery canal 前壁 咽鼓管鼓口 ostium tympanicum tubae auditivae 鼓膜张肌半管口 semicanalis orifice tensoris tympani