What Is the Round Window?

The circular hole on the inner wall of the middle ear drum is also called "round window". The cochlea, which communicates with the labyrinth of the inner ear bone, is closed with a thin film, called the second eardrum. The external lymph in the labyrinth of the inner ear is pressed when the base of the sacrum moves inward, because the fluid cannot be compressed, and the second eardrum can bulge outward.

Chinese name: Worm window
Foreign name: round window

Shape: Round
Area: 2 square millimeters

Physiological layering of wormholes:

The cross section of the temporal bone from the arch-like bulge to the jugular bulb appeared in layers, from 18 to 22 layers from top to bottom, the main window structure of the round window area (spiral window area) is the 9th to 14th layers, with 4 key levels.

Worm cone cone uplift level:

It is the ninth or tenth layer below the arched uplift, which is characterized by the appearance of a cone uplift. In the cross section, the cochlear basal bulge can be seen from the inner wall of the tympanum to form the tympanic protuberance; the bone spine in the middle of the posterior wall of the tympanum is a cone bulge with the deep side of the sacral muscle; the small depression outside the cone bulge is the facial nerve crypt. The deep side of the fossa is the vertical segment of the facial nerve; the small notch on the inside of the cone bulge is the tympanic sinus; at this level, the facial nerve crypt, cone bulge, and tympanic sinus are in a horizontal "3" shape. The thickness of the bone wall of the headland (x ± s) is (0.78 ± 0.11) mm on the right and (0.92 ± 0.18) mm on the left; the right side of the facial nerve recess from the outer surface of the mastoid is (13.9 ± 2.06) mm, The left side is (11.7 ± 1.95) mm; the distance from the facial nerve recess to the vertical segment of the facial nerve is (0.65 ± 0.14) mm on the right side and (0.60 ± 0.17) mm on the left side. The larger dot-shaped bony structure in front of the tympanum is the malleus neck, and behind it is the long anvil feet. The tympanic muscles can be seen between the wall of the drum chamber and the malleus neck.

Round window level:

It is the tenth to eleventh layers below the arched bulge. It mainly shows the structures of the round window, the round window lip, the anterior wall of the iliac crest, and the volute on the deep side of the tympanic cavity. At the junction of the trailing edge of the drum and the inner edge of the drum chamber is a round window, and the depression at the rear outside of the round window is a round window niche. Round window diameter, cymbal depth, cymbal mouth width, cymbal inner diameter, distance between cymbal front wall and drum step. The ossicles in the tympanic cavity have basically disappeared, and the outer side of the bottom of the volute is the external ear canal. At this level, the plane of the round window membrane and the external auditory canal axis mostly intersect at right angles or acute angles, of which 36.7% are right-angled and 63.3% are acute, and no round window membrane plane is parallel to the external auditory canal axis; canal angle The corneal angle of the canal was (105.9 ± 10.8) ° and (149.7 ± 14.6) °. The level of the internal carotid artery, the mastoid atrium, and the jugular bulb are located anterior and posterior to the cochlea, respectively. Cochlear water pipes began to appear. The HRCT scan showed that the density of the cochlea base gyrus was slightly higher than that of the second gyrus.

Round window casement level:

It is the eleventh to twelfth levels below the arched bulge, mainly showing round window niche. At this level, the round window membrane and the second round of the cochlea have disappeared. The cochlea is an arc-shaped bone tube that resembles a "crescent shape"; the upper edge of the cochlear aqueduct has appeared; the round window ridge and the bone wall of the jugular vein socket The distance is shorter than the previous level. The shortest distance between the round window niche and the bone wall between the jugular fossa was right (2.13 ± 1.88) mm and left (2.39 ± 1.43) mm.

The lower level of the round window casement:

This level has reached the lower edge of the round window niche and cochlear gyrus. The center of the section is the tympanic cavity, and the anterior wall of the tympanic cavity is the horizontal level of the internal carotid artery and the eustachian tube. In the posterior wall of the tympanum, the bone plate between the internal jugular vein and the outer ear canal is extremely thin; The salamander is disappearing and the cochlear aqueduct is clearly visible.

Clinical significance of worm window :

The round window area is an important area for modern ear surgery and ear neurosurgery. The round window membrane plays a particularly important role in the process of transmitting sound energy to the inner ear. It is the membrane opening of the bone labyrinth to the middle ear, which acts as a buffer to deform and allow the inner ear fluid to move with the movement of the patella floor. If the round window membrane is immobile and the sacrum moves, the internal and external lymphatics can only have pressure changes without fluctuations. At this time, the Corti device will not produce normal auditory impulses. Round window film is also a toxic substance such as bacterial toxins, chemical drugs and other parts that can easily enter the inner ear. The film may also rupture when the pressure of the middle ear changes suddenly. The external window leakage caused by the rupture of the round window film is considered to be some "sudden deafness". Cause. In clinical practice, cochlear balloon ostomy for Meniere's disease is performed through a round window membrane, and electrodes are inserted through the round window during cochlear implantation. Due to the position and angle of the round window and the presence of the round window lintel, to perform the round window area surgery, to expose the round window membrane, it is necessary to remove some of the bone at the upper and front edges of the round window lintel; be familiar with the thickness of the bone in this part , Canal angle, canal angle, angle between the plane of the round window and the plane of the tympanic membrane, important anatomical signs around the round window, and the adjacency of the structure around the round window, are the keys to successful surgery in this area.