Vertebrae Col sits on the Devils Backbone, a ridge of many small rock pinnacles. The wonderfully apt name for the ridge was suggested by BDA Greig in 1940.
The Main Barlow can be accessed from near Vertebrae Col. Continue NW from Vertebrae Col, sidling around to the snow gully east of pt 1988m and descend that and the gully below to old slumped moraine debris. This is loose and over steepened lower down, and the best route descends to the east under bluffs on gravel to the Farrar Glacier. Watch for rocks. The upper Barlow is a wild and desolate place, clean slabs in some places and horrendously collapsing hillslopes in others.
An alternative is to traverse Mt Barlow.