Assertion: trapezoid's surface | /r/CapableOf | form concave articular surface
Facets:
value: for the metacarpal of the thumb
type: TRANSITIVE-OBJECT
value: for the first metacarpal
type: TRANSITIVE-OBJECT
Source sentences:
text: The distal surface forms a concave articular surface for the first metacarpal or the metacarpal of the thumb .