Endoscopy of the middle ear structures.

The anatomical structures of the middle ear cleft were investigated with endoscopes of angle of view of 0 degree , 3 degrees and 90 degrees (1.7 mm in diameter). Temporal bone blocks donated by lately succumbed patients were studied 3 times in random order. Forty-three anatomical structures of the middle ear cleft were chosen for inspection. The anatomical structures were counted and registered alternately at the time of endoscopy through 4 quadrants of the tympanic membrane. The study included 12,384 observation pieces. The results are presented in tables. The most suitable quadrant of the tympanic membrane and the angle of endoscope for optimal visualization are presented. The visualization is also presented by anatomical structure and by quadrants of the tympanic membrane. The authors' opinion for selection of the most convenient quadrant of the tympanic membrane and suitable angle of endoscope is presented. The majority of the anatomical structures could be visualized with either a 30 degrees or 90 degrees endoscope. There were difficulties in observing the neck of the malleus, the head of the malleus and the lateral semicircular canal. There was no benefit from the use of a 0 degree angled endoscope in the visualization of the middle ear structures.