Experience Tumblr like never before
Thoughts on this:
Carpe diem = sieze the day
Carpals/ metacarpals = bones in the hand
"Carpe diem" and "carpals" have a similar root.
"Carpe" is presumably "to sieze" and you use the hand, and consequently the bones in the hand, to grab something.
Grab = sieze
Therefore, the carpals are used to Carpe diem.