| Linear dimensions and their derivatives |
| ASCh |
Height of the anterior semicircular canal (Fig. 2b) |
| ASCw |
Width of the anterior semicircular canal (Fig. 2a) |
| COh |
Height of the basal turn of the cochlea (Fig. 2b) |
| COw |
Width of the basal turn of the cochlea (Fig. 2a) |
| h/w
|
Shape index of the arc of a semicircular canal or of the basal turn of the cochlea (height/width × 100) |
| IEL |
Inner ear length measured from the posterior-most point of the arc of the posterior canal at its greatest width, to the centre of the lumen of the basal turn of the cochlea |
| LSCh |
Height of the lateral semicircular canal (Fig. 2a) |
| LSCw |
Width of the lateral semicircular canal (Fig. 2a) |
| PSCh |
Height of the posterior semicircular canal (Fig. 2a) |
| PSCw |
Width of the posterior semicircular canal (Fig. 2b) |
| R
|
Radius of curvature of a semicircular canal or the cochlear basal turn, measured to the centre of the lumen (R = 0.5 × [h + w]/2) |
| Orientations |
| APA |
The ampullar line, connecting the centres of the anterior and posterior ampullae, and projected onto the sagittal plane (Fig. 2d). Reflects how the vertical canals are set on to the vestibule in lateromedial view |
| ASCi |
The inferior-most part of the anterior semicircular canal, defined by the line in the transverse plane connecting the apertures of the anterior ampulla and the common crus into the vestibule (Fig. 2c). Labelled as ‘V’ inSpoor & Zonneveld (1995)
|
| ASCm |
The arc of the anterior semicircular canal at its greatest width in the transverse plane (Fig. 2c) |
| ASCs |
The superior-most part of the anterior semicircular canal in the transverse plane (Fig. 2c) |
| CCR |
The common crus in the sagittal plane (Fig. 2d). |
| COs |
The basal turn of the cochlea in the sagittal plane (Fig. 2d) |
| COt |
The basal turn of the cochlea in the transverse plane (Fig. 2c) |
| LSCl |
The lateral most part of the lateral semicircular canal in the sagittal plane (Fig. 2d) |
| LSCm |
The arc of the lateral semicircular canal at its greatest width in the sagittal plane (Figs 2d and 7) |
| LSCt |
The axis of symmetry of the lateral semicircular canal in transverse plane (Fig. 2c) |
| PPip |
The posterior petrosal surface in the transverse plane at the level of the lateral semicircular canal |
| PSCi |
The inferior limb of the posterior semicircular canal in the transverse plane (Fig. 2c) |
| PSCm |
The arc of the posterior semicircular canal at its greatest width in the transverse plane (Fig. 2c) |
| PSCs |
The superior limb of the posterior semicircular canal in the transverse plane (Fig. 2c) |
| SG |
Intersection of the midsagittal plane of the cranium in the transverse plane |
| VSC |
Reference line in the transverse plane based on the vertical semicircular canals. It bisects the angle between the arc orientations of these two canals that opens anteriorly or posteriorly (ASCm, PSCm; Fig. 2c) |
