Table 1.
Abbreviations and descriptions of landmarks, muscle vectors and canal planes
| Abbreviation | Description |
|---|---|
| Landmarks | |
| ASCam | Centroid of the ampulla of the anterior semicircular canal |
| ASCap | Centroid of anterior canal at point most distant from vestibule |
| ASCb | Point on margin of vestibule diametrically opposite the apex of the anterior semicircular canal |
| ASCv | Centroid of the anterior part of the anterior semicircular canal at its inferiormost diameter as it enters the vestibule |
| ASCwA | Centroid of the anterior part of the anterior semicircular canal at its greatest width in the transverse plane |
| ASCwP | Centroid of the posterior part of the anterior semicircular canal at its greatest width in the transverse plane |
| cIOI | Centroid of the inferior oblique muscle as it inserts on the eyeball on the contralateral side |
| cIOO | Centroid of the inferior oblique muscle near its origin on the orbital wall on the contralateral side |
| cIRI | Centroid of the inferior rectus muscle as it inserts on the eyeball on the contralateral side |
| cLRI | Centroid of the lateral rectus muscle as it inserts on the eyeball on the contralateral side |
| cO | Centroid of the optic nerve as it passes through the optic foramen on the contralateral side |
| iMRI | Centroid of the medial rectus muscle as it inserts on the eyeball |
| iO | Centroid of the optic nerve as it passes through the optic foramen |
| iSOI | Centroid of the superior oblique muscle as it inserts on the eyeball |
| iSOO | Point on the medial orbital wall at which the superior oblique muscle abruptly changes direction (trochlea) |
| iSRI | Centroid of the superior rectus muscle as it inserts on the eyeball |
| LSCam | Centroid of the ampulla of the lateral semicircular canal |
| LSCap | Centroid of lateral canal at point most distant from vestibule |
| LSCb | Point on margin of vestibule diametrically opposite the apex of the lateral semicircular canal |
| LSCv | Centroid of the anterior part of the lateral semicircular canal at its medialmost diameter as it enters the vestibule |
| LSCwA | Centroid of the anterior part of the lateral semicircular canal at its greatest width in the sagittal plane |
| LSCwP | Centroid of the posterior part of the lateral semicircular canal at its greatest width in the sagittal plane |
| PSCam | Centroid of the ampulla of the posterior semicircular canal |
| PSCap | Centroid of posterior canal at point most distant from vestibule |
| PSCb | Point on margin of vestibule diametrically opposite the apex of the posterior semicircular canal |
| PSCv | Centroid of the superior part of the posterior semicircular canal at its medialmost diameter as it enters the vestibule |
| PSCwI | Centroid of the inferior part of the posterior semicircular canal at its greatest width in the coronal plane |
| PSCwS | Centroid of the superior part of the posterior semicircular canal at its greatest width in the coronal plane |
| Muscle vectors | |
| cIO | Contralateral inferior oblique muscle: cIOO to cIOI |
| cIR | Contralateral inferior rectus muscle: cO to cIRI |
| cLR | Contralateral lateral rectus muscle: cO to cLRI |
| iMR | Ipsilateral medial rectus muscle: iO to iMRI |
| iSO | Ipsilateral superior oblique muscle: iSOO to iSOI |
| iSR | Ipsilateral superior rectus muscle: iO to iSRI |
| Semicircular canal planes | |
| ASC | Anterior semicircular canal: plane of best fit of ASCam, ASCap, ASCb, ASCv, ASCwA, ASCwP |
| LSC | Lateral semicircular canal: plane of best fit of LSCam, LSCap, LSCb, LSCv, LSCwA, LSCwP |
| PSC | Posterior semicircular canal: plane of best fit of PSCam, PSCap, PSCb, PSCv, PSCwI, PSCwS |