OBJECTIVES: Equations for estimating the planar relationships of the human semicircular canals were devised by Blanks et al from a dissected bony labyrinth in a human skull. However, a similar study on the membranous semicircular canal planes has never been published. METHODS: In this study, the angle between each membranous canal plane and Reid's stereotactic horizontal plane was measured on serial histologic sections of 7 temporal bones from Japanese adults. We reconstructed the 3 semicircular canals by computer-aided 3-dimensional analysis. The angles between each pair of both bony and membranous canal planes were measured. RESULTS: In the bony labyrinth, the angles between the 2 canal planes of the lateral-anterior, anterior-posterior, and lateral-posterior pairs were 90.51 degrees +/- 2.98 degrees (mean +/- SD), 91.70 degrees +/- 1.85 degrees, and 94.52 degrees +/- 3.32 degrees, respectively. The angles between the 2 membranous canal planes of the lateral-anterior, anterior-posterior, and lateral-posterior pairs were 90.05 degrees +/- 4.74 degrees, 91.03 degrees +/- 2.93 degrees, and 91.92 degrees +/- 5.22 degrees, respectively. CONCLUSIONS: The data from our study of the membranous labyrinth showed that the angles between each canal plane and the others were much closer to 90 degrees than was found by Blanks et al for the bony labyrinth.
OBJECTIVES: Equations for estimating the planar relationships of the human semicircular canals were devised by Blanks et al from a dissected bony labyrinth in a human skull. However, a similar study on the membranous semicircular canal planes has never been published. METHODS: In this study, the angle between each membranous canal plane and Reid's stereotactic horizontal plane was measured on serial histologic sections of 7 temporal bones from Japanese adults. We reconstructed the 3 semicircular canals by computer-aided 3-dimensional analysis. The angles between each pair of both bony and membranous canal planes were measured. RESULTS: In the bony labyrinth, the angles between the 2 canal planes of the lateral-anterior, anterior-posterior, and lateral-posterior pairs were 90.51 degrees +/- 2.98 degrees (mean +/- SD), 91.70 degrees +/- 1.85 degrees, and 94.52 degrees +/- 3.32 degrees, respectively. The angles between the 2 membranous canal planes of the lateral-anterior, anterior-posterior, and lateral-posterior pairs were 90.05 degrees +/- 4.74 degrees, 91.03 degrees +/- 2.93 degrees, and 91.92 degrees +/- 5.22 degrees, respectively. CONCLUSIONS: The data from our study of the membranous labyrinth showed that the angles between each canal plane and the others were much closer to 90 degrees than was found by Blanks et al for the bony labyrinth.