Hmmm... I've got an article in progress explaining laminitis, how it works and what it looks like. Seems I need to finish that article. Basically laminar wedge is produced by the laminar corium during a laminitis attack. As the wall and the bone are ripped apart by rotation/sink, the laminar corium gets damaged. There are mechanisms in the laminar corium aimed at repairing damage to the hoof and these try to fill in the gap created as the wall separates away, but because of the damage to the laminar corium, the horn produced is poor quality (full of holes and also full of blood products from the bruising). This wedge of material that ends up between the wall and the pedal bone at the toe is called a laminar wedge.