The topographical anatomy of domestic animals, including that of dogs, has been insufficiently described in current literature. The present study aimed at a systematic measurement and anatomical description of selected size parameters of dog’s temporal bones by performing a dissection of 12 specimens (24 temporal bones). It was noted that the air spaces of dog’s temporal bones are well developed and form a pneumatic system fed with air by the Eustachian tube. The largest element of this system is the tympanic bulla which is situated relatively superficially and creates an important landmark facilitating surgery in the middle ear. After opening the tympanic bulla the promontory is clearly visible as well as all auditory ossicles and tendons of the intrinsic muscles. The study also revealed that the middle ear has several bony recesses, penetrating the majority of the walls of the tympanic cavity and creating almost completely separate compartments. One of these compartments is an air cell situated beneath the facial canal - posterior to the promontory. The facial nerve on this segment is deprived of its bony sheath, and creates a possible path of nerve damage by bacterial toxins during otitis media. Additionally, the proximity of the middle ear with other structures of skull is also important: the epitympanic recess of the middle ear is close to the venous temporal canal, and the region of the orifice of the Eustachian tube is close to the internal carotid artery canal. The semicircular canals are of considerable size, the greatest one being the superior canal and the smallest the posterior canal. Only 4, not 5 openings of semicircular canals in dog’s vestibules were studied because two of them possess common side paths in the bony labyrinth. From the parameters measured the most stable were vestibule size (2×3 mm), and the most variable - cochlea (5.85-7.4 mm of height) and tympanic cavity (14.2-22.6 mm of length). However none of the studied parameters was significantly correlated with skull length.
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