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. 2010 Jun 11;20(6):421–428. doi: 10.1055/s-0030-1261262

Figure 1.

Figure 1

(A) Different areas of bone drilling. V2 canal (dashed line) lies between foramen rotundum at pterygopalatine (FRp) and foramen rotundum at middle cranial fossa (FRm). V2 canal extends through the lateral wall of the inferior part of posterior ethmoids immediately above the sphenopalatine foramen (SPF). FRm and V2 canal lie below the medial end of superior orbital fissure (SOF), and the anterior end of optic canal (OC) and annulus of Zinn lie superior to the medial end of SOF. (B) Bone trajectory (BT) separating SOF from FRm and V2 canal (dashed line). The wide distance between FRp and FRm suggests the V2 canal terminology. The OC inclines away from the skull base as it reaches the posterosuperior angle of posterior ethmoid sinus (PE). MAX P, posterior wall of maxillary sinus; SS, sphenoid sinus.