Bent knees in profile-some quick notes (Rustcity)

Preview:
Some quick drawings + helpful thoughts on how to draw bent knees
Synonyms: knees; legs; lower body
Some notes on the notes:
There is a subtle dip, right above the knee, where the muscle ends. The more muscle a person has, the more pronounced this dip will be. Try and feel it on yourself!
When you bend your knee the knee itself is lower than you would think. The "front" of a bent knee is actually where the femur ends. (This page isn't really about bones so I uh ,,, did not draw them very accurately here)