extremity vs tarsus

extremity

noun
  • A limb (“major appendage of a human or animal such as an arm, leg, or wing”). 

  • The most extreme or furthest point of something. 

  • A hand or foot. 

  • An extreme measure. 

tarsus

noun
  • The true foot or the fifth joint of the leg of an insect or other arthropod, typically consisting of several small segments and ending in a claw. 

  • A plate of dense connective tissue found in each eyelid, attached to either the superior tarsal muscle (in the upper eyelid) or inferior tarsal muscle (lower eyelid), which aid with sympathetic control. 

  • The shank or tarsometatarsus of the leg of a bird or reptile. 

  • A group of small bones in this part of the foot. The seven bones of the human tarsus form the ankle and upper part of the foot. 

How often have the words extremity and tarsus occurred in a corpus of books? (source: Google Ngram Viewer )