Surgical anatomy of the temporal bone in the chinchilla.

The chinchilla is of value in otological research for many reasons, including the surgical accessibility of the majority of structures within its temporal bone. This paper describes the anatomy of the chinchilla's temporal bone, and four surgical approaches to the labyrinth and ossicular chain, three through the bulla and the other via the external canal. No one approach reveals all the temporal bone structures, and each route is therefore more suited to some surgical procedures than others. The cochlea is particularly accessible for microsurgical procedures because it projects into the labyrinthine part of the bulla and because its bony capsule is thin. Surgery in the posterior cranial fossae is both hazardous and difficult; the hazard is bleeding from the venous sinuses which run within the occipital and temporal bones, and the difficulty is the limited access due to the intervening cerebellum and the closeness of the brain stem.