Okay, I know the Spider-people are flexible. I realize that’s part of their powers. However, being flexible doesn’t mean the spine turns to rubber.
I get that the artist wanted to display this contortionist’s abilities by having the legs and pelvis pointed upwards while the web’s being shot in the opposite direction. However, that sort of contortion has the spine collapsing in part of the ribcage, and at first glance all I think is ow, ow, ow. Contortion art, even when it is well done, still has the viewer cringing in imagined pain.
So I settled with flexibility without overt exaggeration. There is still a twist there, but it’s a doable twist, by a ballet dancer or gymnast, and I’ve focused on where the elements of the core sit with each other. Arch the back enough, you’ll crease the flesh (see right hip+ribcage); the shoulders are thrown back so the shoulder blades stick out; the head placement is corrected to fit the new ribcage.
I’ve left in some rough construction lines of the skeleton. They are important when constructing a drawing. Don’t fudge over the interior anatomy, or your outer anatomy, as pretty and correct as it may be, won’t ever look right.