The leg is a complicated part of the body as it’s made up of so many muscles and tendons.
We don’t need to know the names of all of these muscles but It is important to be able to visualise the basic groupings and how they slot together so that we can begin to simplify them.
The best way to simplify the anatomy is to group individual muscles together.
The front of the leg can be broken down into 4 distinct groupings, whereas the back of the leg is made up of 5 groups.
You can simplify things even further in your final art by just picking out small bits of detail from your simplified anatomy.
Your final linework can be as simple as the basic outline of the leg but with a few simple lines of detail. The key is knowing where to put this detail and that’s where an understanding of anatomy becomes invaluable.