This section is from the book "Applied Anatomy: The Construction Of The Human Body", by Gwilym G. Davis. Also available from Amazon: Applied anatomy: The construction of the human body.
When fully distended the normal bladder contains approximately 500 c. c., or a pint. Its capacity varies much, and it is capable of great distention without rupture. In cases of retention of urine it may reach up to the umbilicus and contain a quart or more, while if its walls are thickened it may be contracted and hold only a few ounces. The shape of the bladder is dependent on the amount of dilatation and its attachments.
In front of the bladder is the symphysis and body of the pubes, below and in front is the prostate gland. Beneath is the posterior portion of the prostate, the seminal vesicles, the termination of the ureters, and the rectum. The upper and posterior surfaces are covered by peritoneum and small intestines, which fill the rectovesical pouch. In the female the bladder rests on the upper half of the vagina and the uterus as far as the internal os.
The bladder is fixed at its upper and lower portions. It has true ligaments of fascia and false ligaments of peritoneum. The pelvic fascia is reflected from the levator ani muscles onto the bladder and prostate. Its reflection from the levator ani onto the bladder occurs at its upper portion on each side and is called the lateral true ligaments (Fig. 450). The reflection from the anterior part of the bladder and prostate which goes to the posterior surface of the pubes is called the puboprostatic ligament or anterior trite ligament of the bladder. The urachus forms a superior ligament. The false ligaments are simply the peritoneal reflections. That over the urachus is the anterior false ligament, and those on the sides, which are reflected from the bladder at about the level of the white line are called the lateral false ligaments. When the urachus above is detached the bladder is comparatively loose. Its firmest attachment is at its neck to the prostate and to the rectum above the prostate at the rectovesical pouch. It is this firm attachment which causes the mucous membrane of the base of the bladder to remain smooth while the rest is corrugated.
Fig. 450. - View of the interior of the male pelvis, showing the bladder attachments.
The shape of the bladder is influenced by its attachments. As we have just seen these are the urachus in front, the neck below, and the rectovesical pouch behind; therefore, as the bladder collapses it assumes a conical shape with its apex at the neck and its base running from the top of the symphysis anteriorly to the highest point of attachment to the rectum posteriorly. The bladder never sinks entirely below the top of the symphysis, because the urachus holds it there; as its top or fundus descends it sinks behind the symphysis and slopes back to the rectum. If the bladder-walls are actively contracted or much thickened it cannot readily collapse, and then retains a more elongated shape. As it distends it becomes oval and rises toward the umbilicus (Fig. 451).