Three-Dimensional Graphic Reconstruction of the Tympanic Bulla of the Rat with Special Reference to the Middle Ear Muscles

Abstract

On the basis of functional questions, graphic three-dimensional reconstructions of the tympanic bulla of the rat were made to gain insight into the spatial organisation of the contents of the bulla and especially of the tympanic membrane - ossicular chain - middle ear muscle complex. For this purpose drawings of microscopical sections of complete bullae were fed into the computer to make three-dimensional graphic reconstructions with hidden line removal. From these reconstructions plastic representations were made by the medical artist. The topographical anatomy of the tympanic bulla is discussed in detail and compared to the anatomy of the middle ear in man. It is postulated that, despite differences in spatial organisation of the middle ear of the rat compared to that of man, the middle ear muscles influence the ossicular chain in a comparable way. On the basis of the topographical anatomy it is feasible that the muscles in the rat act synergistically in increasing the stiffness of the ossicular chain.

Key Words:

• stapedius muscle
• tensor tympani muscle
• topographical anatomy
• tympanic bulla.