The middle ear
The middle ear (Auris media; Otos media; engl. Middle ear) belong to the middle ear: The eardrum (tympanum) is a membrane-like barrier between the external auditory canal and the tympanic cavity. With a thickness of 0.1 mm, it is extremely thin, oval and has a diameter of about 8 mm.
On the outside, the middle ear is covered with skin and on the inside with mucosa. During otoscopy, the eardrum is closely examined, as the smallest changes can give an indication of diseases around the ear. When healthy, the eardrum shines grey-yellow and reflects a light reflex of the ear mirror (otoscope).
One of the three ossicles in the ear (hammer = maleus, anvil = incus, stirrup = stapes) is fused to the eardrum from the inside, therefore, the hammer handle can be seen in the upper part of the eardrum during an examination. This part of the ear is very thin and sensitive to pressure. Differences in pressure, caused by diseases, show themselves here in the form of indentations or depressions.
In the case of an extreme inflammation of the middle ear (otitis media), the pus that has developed will seek to drain out through this very spot. The tympanic cavity in the ear (Cavitas tympanica) is a pearl-sized space and contains the ossicles (hammer = maleus, anvil = incus, stirrup = stapes). The ossicles transmit and amplify (impedance) the sound waves from the eardrum to the inner ear.
They are the smallest bones found in the human body and are connected by small joints. Six different walls separate the tympanic cavity from other important organic structures. In the case of inflammation of the tympanic cavity in the ear (otitis media), these neighboring structures can be affected and cause severe inflammatory disease.The eardrum represents the outer wall.
Towards the inside, the tympanic cavity is separated from the oval and round window of the inner ear. A thin but very important facial nerve runs along exactly between these two windows. In middle ear infections, the 7th cranial nerve (facial nerve) is at risk and can lead to facial paralysis if damaged.
At the front, the tympanic cavity is delimited by the auditory trumpet. The posterior wall of the ear is bordered by a bony structure – mastoid process (mastoid, processus mastoideus) – which contains small air spaces (pneumatized). Here too, the 7th cranial nerve runs in a canal and can be damaged in case of inflammation of the mastoid process (mastoiditis).
At the bottom, the tympanic cavity in the ear is bordered by a large jugular vein (Vena jugularis interna). The auditory tube (Tuba auditiva, Eustach ́sche Tube, Tuba pharyngotympanica) connects the middle ear with the nasopharynx and serves to equalize pressure in the ear when overcoming greater heights in diving, mountaineering and flying. This is because there is a pressure difference between the external auditory canal and the middle ear. You can find more anatomical details under our topic: Middle ear
- The eardrum
- The Tube
- The tympanic cavity
- The ventilated (pneumatic) rooms.
