The structure indicated is the hamate bone of the hand.

There are three groups of bones in the hand:

1. Carpal bones (8 in total)
2. Metacarpal bones
3. Phalanges

The carpal bones are separated into two rows:

1. Proximal row
2. Distal row

The hamate bone is one of four bones in the distal row of carpals (hamate, capitate, trapezium, trapezoid). It is named after its small hook-like process (“hamulus” comes from the Latin meaning hook). Several structures attach to the hook of the hamate bone. The hamate bone has the following articulations:

• Radial: capitate
• Ulnar: pisiform
• Proximal: lunate
• Distal: metacarpals of 4^th and 5^th

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