Bone
Lunate
Central bone of the proximal wrist row
High-yield
An extra surface for the hamate is a normal variant: it is present in a type II lunate and absent in type I. Lunate dislocation and perilunate dislocation describe different disruptions of wrist alignment.
Overview
Seen from the side, this carpal bone has a crescent profile. It sits between the scaphoid and triquetrum, receiving the capitate on its distal side and meeting the radius proximally.
Reference facts
- Bone type
- A short bone of the carpus
- Key landmarks
- Rounded proximal surface for the radius; hollowed distal surface for the capitate; a separate hamate facet may be present
- Articulations
- Radius, scaphoid, triquetrum and capitate; also the hamate when a medial distal facet is present
Mnemonic
Read from the thumb side in both rows: proximal S-L-T-P; distal T-T-C-H. Expand each letter into the bone's name as you picture the two rows.
Clinical correlation
A lunate displaced toward the palm can press on the median nerve in the carpal tunnel. This is an urgent traumatic injury; the diagnosis depends on examination and imaging, not wrist pain alone.
Frequently asked questions
What type of bone is the lunate?
A short bone of the carpus.
What does the lunate articulate with?
Radius, scaphoid, triquetrum and capitate; also the hamate when a medial distal facet is present.
What are the key landmarks of the lunate?
Rounded proximal surface for the radius; hollowed distal surface for the capitate; a separate hamate facet may be present.