The structure Y is called the (a)  

The structure R is called the (a)  

The structure L is called the (a)  

The structure E is called the (a)  

The structure F is called the (a)  

What is the human equivalent of the stifle?

(a)  

The human equivalent of structure 2 is (a)  

The human equivalent of structure M is the (a)  

The structure I is called the (a)  

The structure G is called the (a)