A foldable knife, which can be a pocket knife, has a spine with a generally arcuate cutout or indentation, over which is secured a thumb bridge, leaving the indentation open between the spine and the bridge. To open the blade the user extends a thumb below the thumb bridge to pivot the blade out of a slot in the housing. With the blade fully opened, the thumb bridge provides an ergonomic engagement point for the thumb of the user when gripping the handle.