THE BLADDER, URETHRA, AND RECTUM.
The bladder and rectum being contained in the pelvic cavity, and hav ing immediate connections with the internal genital organs, ought to be studied with those organs.
The Bladder.
This is a musculo-membranous reservoir destined for the urine, and which occupies the anterior portion of the pelvic region, in front of the uterus, and behind the pubes.
When it is filled, the bladder has the shape of an ovoid, the large ex tremity of which points downward and forward. When empty it forms an isosceles triangle with the base downward. It presents six regions or surfaces: anterior, posterior, superior, inferior and two lateral.
The anterior surface is adjacent to the posterior surface of the pubes, and the inferior wall of the abdomen. It is attached to these portions by the pubo-vesical ligaments, which are situated on the sides of the bladder. They seem to hang from the superior pelvic aponeurosis, and are formed by muscular fibres which proceed from the muscular layer of the bladder. They are covered by the peritoneum.
The posterior surface is contiguous with the uterus above, and blends with it below. Its connections have already been indicated.
The inferior surface or lower end, is limited in front by the urethra and behind by the vesico-uterine cul-de-sac. It presents for considera tion the trigone, which is situated on the internal surface of the bladder. At the superior angles are the two orifices of the ureters, at the inferior angle the superior orifice of the urethra. The neck of the bladder is formed by the part of the vesical walls which surround this last-named orifice.
The superior surface or apex of the bladder is in relation with the abdominal walls. In its centre is the urachus, a fibrous cord going to the abdominal wall, and inserted at the umbilicus. The urachus is the remains of the pedicle of the allantoic vesicle.
The lateral surfaces face the sides of the cavity, and are accompanied by the umbilical arteries reduced to a fibrous cord.
The relations of the bladder vary according as it is empty or full. In the latter case it depresses the anterior wall of the vagina, thus making in the interior of this organ a larger or smaller projection.
The cavity of the bladder when empty shows folds and projections due to the retraction of the walls, and to the projection of the bundles of the muscular coat.
consists of a serous, a muscular and a mucous membrane.
Serous is covered by the peritoneum, only at the pos terior, lateral and superior regions. From here it folds forward upon the abdominal walls .78 to 1.1 inches above the superior margin of the pubes, behind on the anterior surface of the uterus, and there forms the vesico uterine cul-de-sac.
Muscular has three layers: a superficial, composed of longitudinal fibres; a middle, of circular fibres; an internal, of fibres that interlace in all directions. At the neck of the bladder the circular fibres form a true sphincter.
The mucous membrane is pale, thin, smooth, covered with pavement epithelium, and adheres feebly to the muscular membrane. It forms numerous folds in the interior of the vesical cavity.
The arteries come from the hypogastric and its branches.
The veins form an important plexus about the neck and inferior part of the organ. They join the hypogastric vein.
Sappey denies their existence, but, according to other authors, the lymphatics of the mucous membrane go to the pelvic glands.
The nerves come from the hypogastric plexus.
The Urethra.
This leads from the neck of the bladder and ends at the urinary meatus. Its length is about 1.5 inches, its width about .27 inches. It is slightly oblique from above downward, and from behind forward, and is very dilatable. It describes a curve, concave in front, which corresponds to the posterior surface of the symphysis. Its inferior extremity passes be tween the roots of the clitoris, below the free edge of the triangular liga ment from which it is separated by cellular tissue.