The Intercarpal ligaments in red. These ligaments define the coronal axes of movement of the carpal bones.

Thus a 'weak zone' can be seen in the centre of the carpal architecture which will both allow for maximum opening of the palm and for aberrations of carpal algnment in the central weak zone: in yellow

Pivot point in carpal abduction / adduction

Abduction / adduction of the wrist x-ray