That stopped him. He tried different moves - pointing my toes, not pointing them, lowering the leg about halfway (relief), asking about the pain in each change. Then he said it may be "neural tension".
According to Brent Anderson, PhD, PT, OCS,
This is pretty close to how Wade described it. He said the nerve goes all the way from my brain to the bottom of my foot, one continuous nerve, and if it gets stuck along the way it can't move as it should. He then had me lie on my back and when he moved my foot I was to move my head - bring my chin to my chest. This is one of the exercises for loosening up the nerve. When we had done it several times he tested me again and the pain was not as great. So I may indeed have a nerve issue there. He suggested that I ask the next physical therapist (Paul) to do a neural tension test.
NT is thought to be caused by restriction on the sheath that surrounds the nerve. The nerve should glide smoothly through the sheath like a bicycle brake cable gliding through its casing. But sometimes the nerve does not glide through the sheath well and this can cause restriction.
I got interested in this topic and looked around a bit online. It appears that this is a relatively new area and there isn't always agreement about what is going on and how to deal with it. There is a book, written in 2005, that offers many illustrations and explanations, and that gets good reviews. Just for yucks, I went to betterworldbooks.com to see if they had it, and they did. But new it costs almost $115, and used it is over $80. I guess I'll not be satisfying that part of my curiosity just yet.