Since you have such a wonderful book that has already helped me, I'd like to give back with two suggestions for the next revision. Here's the first:
In a number of instances you refer to a structure but don't tell the reader what or where it is. For example, in figure 3-9, you refer to the pubic bone. Ask 100 people on the street to identify the pubic bone, and you'll be lucky to find 2 or 3 who can do it. You might even label the pelvis in this illustration.
In figure F25a, you mention the L5-S1 disc, but the reader has to figure out which one it is. Yes, you can logically deduce which one it is from F25b, but I'd recommend labeling the figure as I have done below.
As a final example, on page 114, you refer to the oblique and transversus muscles, but nowhere are those labeled or described. I looked on page 218 expecting to find them labeled, but they are not. Unless I look on the Internet, those names are useless to me.
It's a minor thing, but perhaps you will find this suggestion useful.