Planar Relationships Of The Semicircular Canals In Man

Abstract

Principalcomponent 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 synergisticany 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=l 1 I"). Pairs of contralateral synergistic canal planes formed angles of 19" between right and left horizontal canal planes and 23-24' between vertical canal pairs. horizontal plane. Mathematical equations of the semicircular canals were used to predict the optimal head position for rotational and caloric stimulation.

A Mathematical Model of Human Semicircular Canal Geometry: A New Basis for Interpreting Vestibular Physiology

“…Reid's plane is defined as the plane that passes through the center of each external auditory canal and the inferior margin of the two orbits (Blanks et al 1975). The coordinate system is defined from the orthogonal basis formed by the axes of this plane.…”

“…The reduced span weightsR Original data from Blanks et al (1975), consisting of bony canal centroid data points taken from dried skulls, were compared to the results from our current study. This revealed that the original measurements did not include the entire canal path: data points were not taken in the region of the common crus and the ampulla due to difficulties with the dissection.…”

“…The inclusion of the common crus region contributes an average of 2°to the result. Most importantly, the weights that attempt to replicate measurements made by Blanks et al (1975) result in differences of up to 10°. The crosssectional area-based weight, which attempts to account for the functional plane, influences the posterior and superior canals by 4°and the horizontal only marginally.…”

“…1; Sato et al 1993;Ifediba et al 2007;Blanks et al 1975;Della Santina et al 2005). The effect of non-orthogonality of the SCCs has been explored (Ifediba et al 2007;Curthoys and Oman 1987); however, little is known of the variability within and between subjects.…”

“…The effect of non-orthogonality of the SCCs has been explored (Ifediba et al 2007;Curthoys and Oman 1987); however, little is known of the variability within and between subjects. Two accepted studies of SCC geometry have specified the location of average human SCC planes in the head (Blanks et al 1975;Della Santina et al 2005), but have a large discrepancy with each other. By using our current data, we have reconciled this discrepancy.…”