[The Eustachian tube in HR computerized tomography. Imaging in the adult]

Until now the lumen of the Eustachian tube (ET) has always been shown by using histological sections of temporal bones, which were after decalcification embedded in paraffin blocks and serially sectioned. In order to avoid changes caused by this preparations, we applied contrast medium or air to the lumen of the ET of cadaver temporal bones resected immediately after exitus. It was therefore possible to demonstrate the lumen of the tube in high resolution computed tomography. In this way we could find clear variations of the lumen in the total length of the ET and divide it into five different topographically specific regions. Whereas the pars ossea is formed by certain bone formations and structures in various ways, the picture of the cartilaginous portion remains the same: At the connection of the pars ossea to the isthmus the lumen shows an almost circular form which becomes oval towards the end of the isthmus. This can also be found in the preisthmus portion. In the intermediate section the oval shape is interrupted and replaced by a double curve in the form of a reverse "S". We find once again in the pharyngeal section a well-formed oval lumen, which however is more pronounced than in the preisthmus portion. The intermediate section with its double curve is defined by us beside the isthmus region, as a further, second physiological isthmus in the course of the ET. Apart from that the demonstration of the lumen, that of the function unit of the tensor palatine muscle, processus pterygoideus and hamulus is also of special interest.(ABSTRACT TRUNCATED AT 250 WORDS)