Navicular
Short bone; part of the limb (appendicular) skeleton
Also known as: The boat bone or scaphoid of the foot
Classification
Short bone; part of the limb (appendicular) skeleton
Dimensions
In humans, this bone is typically wider than it is long, measuring about one to one and a half inches across, appearing somewhat disk-like or bowl-shaped.
Key Features
It is easily identified by its unique concave surface on the back side, which looks like a shallow cup or a hollowed-out boat. The front side features several flat, smooth faces where it meets the three bones that lead to the toes, giving it a somewhat faceted appearance.
Similar Bones
The cuboid bone is a common lookalike but is more square and blocky. While the navicular is shaped like a flattened boat or bowl, the cuboid lacks that deep concave 'cup' on its back edge. It might also be confused with the talus, but the talus is much larger and has a very smooth, rounded dome for a hinge-like joint.
Across Species
In horses, this bone is relatively small and wedge-shaped, sitting behind the coffin bone within the hoof. In cloven-hoofed animals like deer or cows, the navicular often fuses with other nearby bones to create a more stable, solid block suited for supporting heavy body weight during rapid sprints across uneven terrain.
Evolutionary History
Tracing back to early land-dwelling vertebrates, this bone originated as a modular central element in the mid-foot. As primates transitioned to upright walking, the navicular shifted to act as a 'keystone' for the foot's inner arch, providing a stable lever for pushing off the ground while maintaining the flexibility needed for various terrains.
Photography Tips
To capture the best identification features, photograph the bone from the top down and from the back edge to show the characteristic curve. Placing it next to a ruler or a common coin helps viewers understand its relative size in the mid-foot assembly.
Notes
what is the highlighed part