The Levator Ani aka pelvic floor consists of the Puborectalis , Iliococcygeus , Pubococcygeus and the Coccygeus . Like a hammock supporting the all the lovely innards above , I wouldn't exclude its vital role when accessing a woman's kyphotic curve and her personal sense of self. Strengthening the posterior chain , opening up the front line along with those hip flexors are great but working the pie completes the picture !
Activate the bottom quadrants
Lying down , face up , flatten your lower back into the ground , bite the left butt cheek into the ground , the right knee will elevate slightly off the ground.
Repeat with other cheek , check for difference in strength or recruitment ability.
Activate the upper quadrants
Lie down , face up , close your eyes , gently look to the left without turning your head , with mental focus , clench the top left quadrant close to the pubic mound. Repeat on the other side. You might feel your hips twisting to the quadrant you are activating and that is okay. Learn to minimize that as you get stronger.
To work all 4 quadrants
Or use it as a whole . Imagine holding a cherry by the stem with the pelvic floor on the inhale, picking it up on the exhale , feel the lift of the pelvic floor .. Holding the clench with a lift of the pelvic floor on the exhale is one option , the other involves holding it up along with the breath on the inhale and only releasing ( both pelvic floor and breath ) on the exhale. As you get familiar , it is now time to breath in and out smoothly with maintaining the lifted hold of the pelvic floor.
Combining pelvic floor work with dynamic movement works too , especially back bridges with hips thrusting off the ground with entire pelvic floor braced. I have tried this with squats , pullups , chin ups . Its all good and I enjoy trying to recruit those muscles after a prolonged periods of sitting.
If there is ever an overt tightness of the posterior pelvic floor , you can try these methods that have worked for me. However , there are cases of the pelvic floor being too tight , accessing if it is too high or low is beyond the scope of this article and seeking a Rolfer who does body reading could help.
Here we can see Acro Yoga practitioners Brenda and Dek in the throne pose.
References & further reading
Atlas Of Human Anatomy - Frank H. Netter - Plate 338
The Fine Art Of Pompoir : The ultimate guide to pelvic floor fitness - D.A. Da Costa
Balancing The Pelvis DVD Series - Anatomy trains , Tom Myers
The Pregnancy Survival Guide - Bellies Inc