Topographical anatomy of the middle and inner ear of rabbits.

摘要

In the available literature there is no fully sufficient and exhaustive description of the topographical anatomy of a rabbit's temporal bone. An anatomical study was conducted on 24 rabbits' temporal bones obtained from 12 individuals of both sexes, routinely euthanized after drug tests. The external acoustic meatus is situated obliquely to the lateral skull surface. The mean length of the bony part of the external acoustic meatus is 6.42 mm. In close proximity to the external acoustic pore lie the stylomastoid and postglenoid foramina, situated about 5 mm from the pore rim. The tympanic cavity is divided into several compartments. Among them, the largest ones are: epitympanic recess and tympanic sinus. The epitympanic recess is a cave of a diameter of about 3.5 mm. From the lateral side it is closed by a root of the zygomatic process, and a medial wall of the external acoustic meatus. From the medial side its wall creates the prominence of the anterior semicircular canal, neighboring with subarcuate fossa. Ventrally it is bordered by the facial canal and in this wall the prominence of the lateral semicircular canal is clearly visible. The tympanic recess is frontally bordered by the promontorium, superiorly by the facial canal, ventrally and medially by the bony wall surrounding the jugular foramen, embracing the internal jugular vein and cranial nerves: IX, X, XI. The promontory is the clearest topographical landmark in the tympanic cavity; however, it is not visible from the external acoustic meatus but only after passing the tympanic bulla opening. Frontally from promontory runs the carotid artery in its internal own canal. The mean minimal distance between carotid canal and round window is 4.34 mm. The easiest and safest approach to the tympanic cavity leads either through the epitympanic recess or through the ventral wall of the tympanic bulla. It is important to bear in mind the close proximity of the facial nerve and temporal canal in the first one and carotid artery and the jugular foramen in the second one..