Hamate
Short bone; part of the limb skeleton (specifically the wrist or carpus).
Also known as: Hooked bone, wrist bone
Classification
Short bone; part of the limb skeleton (specifically the wrist or carpus).
Dimensions
In humans, it is roughly the size of a large marble or a small walnut, characterized by its distinct three-cornered wedge shape and a prominent bony protrusion.
Key Features
The hamate is most easily recognized by its 'hook'—a curved, finger-like projection that sticks out from the main body of the bone. Its overall shape is like a wedge or a slice of pie, with several smooth, flat faces where it meets other bones in the hand.
Similar Bones
It can be confused with the pisiform (a small pea-shaped bone) or the triquetrum (a pyramid-shaped bone). However, the hamate is unique because it is the only wrist bone with a large, curved projection (the hook). If the bone lacks a clear hook, it is likely one of the other wrist bones.
Across Species
The hamate is found in the wrists of most four-limbed land animals. In some climbing primates, the 'hooked' feature is very large to provide strong attachment for muscles used in gripping branches. In contrast, in many hoofed mammals like horses, these wrist bones are modified into blocky, shock-absorbing structures designed for the high impact of running rather than grasping.
Evolutionary History
This bone evolved as part of the complex wrist joints that allowed early tetrapods to support their weight on land. Over millions of years, as mammals adapted to different environments, this bone shifted from a simple circular shape to a specialized wedge that helps lock the other wrist bones together, providing stability for both manipulative tasks and weight-bearing.
Photography Tips
To identify this bone from a photo, take one shot from the 'top' looking down at the flat surfaces and another from the 'front' profile to clearly show the hook sticking up. Use a small coin for scale and ensure the lighting is angled to cast a shadow behind the hook to make it stand out.
Notes
What is the highlighted part?