Which of the following is the commonest accessory bone of the foot (AIIMS May 2010)
a. Accessory navicular also called prehallux, Os tibiale externum and navicular secondarium, is the commonest accessory bone of the foot.
b. Extra small bones are occasionally found in the foot. Each originate from a separate ossification centre in a tarsal or metatarsal bone that fails to fuse with the main bone.