Fig. 4.

The initial entry point may be difficult to locate in some cases. a ‘Lamina/spinal process junction (yellow arrow), close to the rostral margin (blue arrow) of the lamina’, mentioned by Wright. b In this case, the ‘lamina/spinal process junction’ and ‘rostral margin of the lamina’ were at different levels. c In this case, the entry point was difficult to locate by Wright’s description because there is no an obvious boundary between the lamina and spinal process. The rostral margin is difficult to follow