Jo Wagner Drawing Lesson 5

Sketches made by my grandmother, converted to illustrator file. By Illustrator tracing these sketches, I'm hoping to absorb her powers of artistic depiction by osmosis.
"1. Muscle goes down palm side and spreads down to fingers as means of tendons...Does not look like would easily close when in gesture known as cranation...Muscles twist and go around thumb side...The arm appears open here so that it can easily close as in flexing arm...Ulna can be traced on back of arm because of muscles lying parallel to it and causing groove...Volume mostly bone here (elbow)"