Navicular
Short Bone, part of the limb (appendicular) skeleton.
Also known as: Boat Bone, Scaphoid of the Foot
Classification
Short Bone, part of the limb (appendicular) skeleton.
Dimensions
A small, somewhat flattened bone that is notably wider than it is long, typically measuring about an inch to an inch and a half across in an adult.
Key Features
The most distinctive feature is its curved, boat-like shape. The back surface (facing the ankle) is deeply cupped like a small bowl to receive the rounded head of the ankle bone. The front surface is flatter and divided into three distinct facets where it meets the wedge-shaped midfoot bones. There is often a noticeable rounded knob on the inner side that can be felt through the skin on the arch of the foot.
Similar Bones
It is often confused with the Cuboid bone. You can tell them apart because the Navicular is moon-shaped or boat-shaped and sits on the inner side of the foot (big toe side), while the Cuboid is more square and blocky and sits on the outer side of the foot (pinky toe side).
Across Species
The navicular is a key architectural piece in the arches of many land-dwelling mammals. In horses, while much of the foot structure is simplified for speed, the 'navicular bone' (actually a small bone behind the coffin bone) is famous for its role in supporting the hoof. In primates, this bone is essential for flexible climbing, whereas in humans, its bowl-like shape helps lock the foot into a rigid lever for efficient upright walking.
Evolutionary History
This bone originates from the central tarsal elements of early tetrapods. Over millions of years, as our ancestors transitioned from flat-footed forest dwellers to specialized endurance runners, this bone moved into a central position to help support the inner arch. Its crescent shape is a hallmark of the change from a grasping foot to a weight-bearing platform.
Photography Tips
To identify this bone, take a photo looking directly at the deeply cupped 'bowl' side. A side-view photo showing the rounded inner knob is also very helpful. Place a coin or a ruler next to the specimen to provide a sense of its small scale.
Notes
Blue highlighted part of foot