The structure indicated is the hamate bone of the hand.
There are three groups of bones in the hand:
- Carpal bones (8 in total)
- Metacarpal bones
The carpal bones are separated into two rows:
- Proximal row
- 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 4th and 5th
Learn more about the bones of the hand in this anatomy tutorial.