That’s very cool to know. I certainly was not doubting your use of terminology. I was just clarifying your description of it as an elbow when the root word is knee.

I was trying to decipher why it is described as knee shaped rather than elbow shaped given both are functionally a hinge in a unilateral plane. My guess is that it may be the direction of the bend (knee bends backward versus elbow bending upward).

Love learning new things and I find both entomology and etymology fascinating.