Investigation of temporal bone anatomy by plastic moulding and cryomicrotomy.

To increase our understanding of the complex topographic relations between temporal bone structures and to facilitate the interpretation of their radiographic images, two techniques were developed. Plastic moulding of temporal bone specimens using polyester resin and silicone rubber substances providing detailed information and a three-dimensional survey of the structures. Carefully macerated temporal bone specimens are filled with plastic material under vacuum and the bone is then dissolved. The preparations, freed from irrelevant structures and embellished, allow metric evaluation of the different structures and their topographic relations. Automatic serial cryomicrotomy of fresh, deep-frozen temporal bones, using a commercial sledge-cryomicrotome. Photography of the cut surfaces of the specimen, usually at distance of 0.25 to 0.50 mm, allows natural-colour reproduction of minute detail, e.g. the melanin cell area in the cochlea, the smallest vessels on the ossicular surfaces, and the origin of the cochlear aqueduct at the basal turn of the cochlea. By correlating the photographs with images from the corresponding tomographic planes accurate information is obtained for interpretation of the radiographic images. A combination of the two techniques facilitates a detailed study and is a valuable aid in the teaching of temporal bone anatomy.