Planar Relationships Of The Semicircular Canals In Man

Abstract

Principal-component analyses were determined on a series of points measured from the dissected bony labyrinth of ten human skulls, resulting in planar equations for each of the six semicircular canals. Following this, angles were calculated between the ipsilateral canal planes, between opposite synergistically acting canal planes and between each canal and the Reid stereotaxic planes. Results indicated that pairs of ipsilateral canals were nearly perpendicular, with the exception of the angle formed between the anterior and horizontal canal (mean = 111 °). Pairs of contralateral synergistic canal planes formed angles of 19° between right and left horizontal canal planes and 23–24° between vertical canal pairs. The horizontal canals formed an angle of 25° with the Reid horizontal plane. Mathematical equations of the semicircular canals were used to predict the optimal head position for rotational and caloric stimulation.This investigation was supported in part by U.S. Public Health Service Grant NS-06658; by the Health Sciences Computing Facility, University of California, Los Angeles, sponsored by NIH Special Research Resources Grant RR-3; and by a grant from the National Health and Medical Research Council of Australia.