Front splits anatomy question please

[Donna Stole]

Would love to have some help in regards to the difference anatomically between what is stretched in a straight front split and an open front split (open where the back knee turns out instead of knee straight down.  The reason I am asking is because I have been working my way towards splits, and find a big difference between the way my hip feels on the back leg when I turn it out rather than straight.  Wondering when you rotate your hip out, what muscle is added in there? I assume it is one of the adductor muscles, but also could be the rectus femoris attachment?  I'm hoping someone might know as it is more painful to do the open or turned out version and whether right or wrong, I am trying to address the discomfort through trigger point work as I have a history with psoas issues.

Thanks if you can help!!

Edited May 18, 2017 by Donna Stole

[Alessandro Mainente]

 Hey Donna, the normal front split there the knee it's facing the floor shows more hips flexor elasticity, while the tendency of the inner knee to move closer to he floor reflects poor hips flexor elasticity and it is the most common mistake, here the body compensate with one adductor .