ABSTRACT
The urinary bladder has a strong smooth muscle wall or detrusor muscle. In adults, the empty bladder lies within the true pelvis, but in children, it is predominantly within the abdominal cavity.
The bladder has a base, superior, two inferolateral surfaces, and an apex (Fig. 1). The posterior surface is described as the base, about halfway along the base on either side of the midline lie the ureteric openings. The ureters enter the bladder obliquely so that during voiding they are compressed, thus preventing reflux of urine. The superior and inferolateral surfaces unite anteriorly to form the apex of the bladder. The median umbilical ligament, an embryological remnant of the urachus, connects the apex to the umbilicus. The neck of the bladder becomes continuous with the urethra, and the smooth muscle around the neck forms the internal sphincter of the bladder. The mucosal lining of the bladder is thrown into folds or rugae, except in the triangular-shaped region of the trigone between the ureteric and urethral orifices, where it is relatively smooth. Ligaments hold the neck in place in the true pelvis. Anteriorly, in males, the bladder neck is attached to the posterior surface of the pubic symphysis by the puboprostatic ligament and in females, by the pubovesical ligament. Fractures of the pubis in this region may cause trauma to the bladder. The lateral ligaments of the bladder and the tendinous arch of the pelvic fascia also hold the neck of the bladder in place.
