To study up on the pelvic muscles, I made a model out of felt, yarn and a box lid.
The box lid represents the bony pelvis. The top is the pubis (pubic bone) and the bottom is the tailbone, or coccyx.
The three strings/ribbons represent the sphincters: yellow=urethra, pink=vagina, brown=anus. I just put them in there to hold the space. You can see in the first picture the superficial muscles: ischiocavernosus (the white diagonal), urethral sphincter (white curvy part), superficial transverse (big blue, clearly labeled), and external anal sphincter (green).
Once you peel away the superficial layer, you can see the deeper layer with the red pubovaginalis, puborectalis and pubococcygeus. These are the kegel muscles, very good idea to strengthen these if you have a vagina and like to use it. Prevents urinary incontinence and, I'm told, adds sensation for your lover.
And the deepest level, you can see the iliococcygeus (green) and ischiococcygeus (blue). And that's it!