Figure 2:

Intraoperative photograph demonstrating left suboccipital muscle dissection. (a) After inferolateral elevation of the superior oblique muscle (SO) from the rectus capitis posterior major muscle (RCPM), the inferolateral border (dashed line) of the RCPM was identified as the landmark of the third segment of the vertebral artery (V3) and the starting point for the bipolar cutting technique to separate the SO from the V3. (b) Magnified photograph of Panel A demonstrated the inferolateral border (dashed line) of the RCPM and the partially elevated SO.