Nathan on Sun, 03 June 2012 9:32am
The bony landmarks you're pointing at down the belly are the iliac crest and anterior superior iliac spine (the upper border of your pelvis). The external obliques grab onto the iliac crest to some extent and then, in the front, on a big fascia that separates this muscle from the abs.
By the way, the abs are asymetric and not everyone has 6 packs. The two top ones exist but just don't develop for some people. You can also find bodybuilders with an 8 pack.
And there's one important thing on your model : you're drawing the clavicle straight. It shows more of an S shape in reality, you can feel this on your very own bone actually and cross check with reference.
Last but not least, the serratus anterior inserts much more horizontally on the ribs, at least on the 5th, 6th, 7th ribs. Can check it by yourself :
thanks for the instructionnal vid anyway,