The structure highlighted is the navicular bone of the foot.

The foot contains three groups of bones:

1. Tarsals
2. Metatarsals
3. Phalanges

The navicular is one of seven tarsal bones. There are three groups of tarsal bones:

1. Proximal group
2. Intermediate group
3. Distal group

The navicular bone is the only bone in the intermediate group and is located medially in the foot. Posteriorly, the navicular articulates with the talus. Anteriorly, the navicular articulates with the cuneiform bones and laterally it articulates with the cuboid bone.

There is only one muscle which attaches to the navicular bone: the tibialis posterior. It attaches onto the tuberosity of the navicular bone.

Learn more about the bones of the foot in this anatomy tutorial.