After the delivery of the head, there's restitution, where the head externally rotates so that the shoulders can pass through the pelvic outlet and under the symphysis pubis.
And finally there's expulsion, where the anterior shoulder slips under the symphysis pubis, followed by the posterior shoulder, and then finally followed by the rest of the body.
The bladder is a hollow, collapsible sac that temporarily stores urine. Like the kidneys, it's retroperitoneal, located posterior to the pubic bone and anterior to the rectum.