But in Morton's foot, the line has to bend more sharply to go through the base of the big toe, as shown in the diagram. This is because the first metatarsal, behind the big toe, is short compared to the second metatarsal, next to it. The longer second metatarsal puts the joint at the base of the second toe (the second metatarsal-phalangeal, or MTP, joint) further forward.