Anatomia topograficzna ucha srodkowego i wewnetrznego kota

The topographical anatomy of domestic animals, including cats, has hitherto not been thoroughly described. In the present study a systematic anatomical description and measurements of selected size parameters of temporal bones as well as skulls was performed on the basis of the dissection of twelve specimens (24 temporal bones). Air spaces of the middle ear in the cat are well developed, creating a pneumatic system where the Eustachian tube delivers fresh air. The greatest element of this system is the tympanic bulla. It is situated superficially and is an important landmark and an easy surgical path to the middle ear. After opening the tympanic bulla a bony septum is visible dividing the bulla into two parts: the ventro-medial and the dorso-lateral. Two openings communicate these almost fully separate spaces. One opening lies frontally to the promontory, another one is situated caudally to the round window niche. The tympanic cavity has several recesses, penetrating into its walls, and creating separate compartments to a certain degree. One of these compartments is epitympanic recess, embracing the head of the malleus and trunk of the incus, as well as an air cell beneath the facial canal, situated posteriorly to the promontory. The stapedius muscle is of considerable size, and is situated in the inferior part of the facial canal, superiorly to the oval window and partly rounded by the lateral semicircular canal. The semicircular canals are of considerable size also, although the superior one is the greatest and posterior one is the smallest. It was stated that in the cats vestibule there are only 4 not 5 openings for the semicircular canals, because of presence of two common crura. From among the measured size parameters the most stable were diameters of semicircular canals (about 3-4 mm), while the most variable - the size parameters of the tympanic cavity. The maximal height of the tympanic cavity, measured between two extreme points (tympanic bulla - epitympanic recess) was 13.2-16 mm, and the maximal length, measured from the posterior wall of the tympanic cavity to the internal opening of the Eustachian tube, was 14.8-18.6 mm. There was no parameter significantly correlated with the total length of the skull.