1/9/2024 0 Comments Aural pressurethe sphenoid sinuses, in the sphenoid bone at the centre of the skull base under the pituitary gland.the ethmoid sinuses, which are formed from several discrete air cells within the ethmoid bone between the nose and the eyes.the frontal sinuses, superior to the eyes, in the frontal bone, which forms the hard part of the forehead.the maxillary sinuses, the largest of the paranasal sinuses, are under the eyes, in the maxillary (cheek) bones.Sinuses are cavities within a bone or other tissue, and humans have many around their bodies.įor flight, we are concerned mostly with the “paranasal sinuses”, which are a group of four paired air-filled spaces that surround the nasal cavity and they are named after the facial bones in which they are located: Paranasal Sinuses (photograph by Hellerhof) Normally the walls of the Eustachian tube are collapsed, and jaw-moving actions such as swallowing, talking, yawning and chewing open the tube to allow air in or out as needed for equalisation. This is achieved via the Eustachian tube which connects the tympanic cavity to the throat/nasopharynx and acts as a pressure release valve to equalise the middle ear pressure to that outside. This means the air pressure within the middle ear must equal that of the external environment. For the eardrum to have maximal mobility, the air pressure on either side must be equal. The tympanic cavity is air-filled and carved out of the temporal bone. Normal Operation of the Middle EarĮfficient hearing requires an intact tympanic membrane (eardrum), a normal ossicular chain, and a well-ventilated tympanic cavity. This amplification is variable, depending on the frequencies higher frequencies need less amplification for transmission to the cochlea. It is these tiny bones that create the mechanical amplification. stapes (stirrup) which is attached to the oval window.incus (anvil) which links the two other bones.malleus (hammer) which adjoins the eardrum.The eardrum is attached at the umbo to the ossicular chain, which consists of three tiny bones:
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