Bottom of the U / Transverse Couple

When I do the transverse couple I always feel like there has to be this release and/or connection happening somewhere amongst these muscles pictured below.

After that first part happens then if I'm doing it right I can feel a transverse stretch sensation. Now when I work on the transverse stretch I also feel a release and/or connection happening between the inner leg and the center bottom of the pelvic area or perenium. I'm also kind of feeling like the transverse couple also has a vertical stretch happening as well that maybe is connecting with the back of the U. Is the bottom part connection just the bottom of the u or is this a part of feeling the transverse couple? Or are the transverse couple and the bottom of the U just part of the same thing.

Motions of the Joints of the Pelvis (sacroiliac joints)