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110 Commentary on plates 48 & 49.

The urinary bladder, G, Plate 49, (in the adult body,) occupies the true pelvic region when the organ is collapsed, or only partly distended. It is situated behind the pubic symphysis and in front of the rectum, C,--the latter lies between it and the sacrum, A. In early infancy, when the pelvis is comparatively small, the bladder is situated in the hypogastric region, with its summit pointing towards the umbilicus; as the bladder varies in shape, according to whether it be empty or full, its relations to neighbouring parts, espe­cially to those in connexion with its summit, vary also considerably. When empty, the back and upper sur­face of the bladder collapse against its forepart, and in this state the organ lies flattened against the pubic symphysis. Whether the bladder be distended or not, the small intestines lie in contact with its upper sur­face, and compress it in the manner of a soft elastic cushion. When distended largely, its summit is raised above the pubic symphysis, the small intestines having yielded place to it, and in this state it can be felt by the hand laid upon the hypogastrium.

The shape of the bladder varies in different indivi­duals. In some it is rounded, in others pyriform, in others peaked towards its summit. Its capacity varies also considerably at different ages and in different sexes. When distended, its long axis will be found to coincide with a line passing from a point midway between the navel and pubes to the point of the coccyx, the obliquity of this direction being greatest when the body is in the erect posture, for the intes­tines now gravitate upon it. When the body is recumbent, the bladder recedes somewhat from the pubes, and as the intestines do not now press upon it from above, it allows of being distended to a much greater degree without causing uneasiness, and a desire to void its contents.

The manner in which the bladder is connected to neighbouring parts is such as to admit of its full distension. Its summit, back, and upper sides are free and covered by the elastic peritonaeum, whilst its front, lower sides, and base are adherent to adjacent parts, and divested of the serous membrane. On tracing the peritonaeum from the front wall of the abdomen to its point of reflexion over the summit of the bladder, we find the membrane to be in this part so loosely ad­herent, that the bladder when much distended, raises the peritonaeum above the level of the upper margin of the pubic symphysis. In this state the organ may be punctured immediately above the pubic symphysis without endangering the serous sac. When the blad­der is collapsed, the peritonaeum follows its summit below the level of the pubes, and in this position of the organ such an operation would be inadmissible, if indeed the necessity for it can now be conceived.

By removing the os innominatum, A D, Plate 48, to­gether with the internal obturator, and levator ani muscles, which arise from its inner side, we obtain a lateral view, Plate 49, of the pelvic viscera, and of the vessels &c. connected with them. Those parts of the bladder, G, and the rectum, C, which are invested by the peritonaeum, are also now fully displayed. On tracing this membrane from before backwards, over the summit of the bladder, G, we find it descending deeply upon the posterior surface of the organ, before it becomes reflected so as to ascend over the forepart of the rectum. This duplicature of the serous mem­brane, H H, is named the recto-vesical pouch, and it is required to ascertain with all the exactness possible the level to which it descends, so as to avoid it in the operation of puncturing the bladder through the rec­tum. The serous pouch descends lower in some bodies than in others; but in all there exists a space, of greater or less dimensions, between it and the prostate, V, whereat the base of the bladder is in direct apposi­tion with the rectum, W, the serous membrane not in­tervening.

When the peritonaeum is traced from one iliac fossa to the other, we find it sinking deeply into the hollow of the pelvis behind the bladder, so as to form the sides of the recto-vesical pouch; but when traced over the summit of the bladder, this organ is seen to have the membrane reflected upon it, almost immediately below the pelvic brim. At the situations where the peritonaeum becomes reflected in front, laterally, and behind, upon the sides of the bladder, the membrane is thrown into folds, which are named "false liga­ments."

COMMENTARY ON PLATES 48 & 49. 111

The pelvic fascia, in being reflected to the bladder from the front and sides of the pelvis, at a lower level than that of the peritonaeum, forms the "true ligaments." In addition to these ligaments, which serve to keep the base and front of the bladder fixed in the pelvis, other structures, such as the ure­ters, K, the vasa deferentia, I, the hypogastric cords, the urachus, and the bloodvessels, embrace the organ in various directions, and act as bridles, to limit its expansion more or less in all directions, but least so to­wards its summit, which is always comparatively free.

The neck and outlet of the bladder, V, are situated at the anterior part of its base, and point towards the subpubic space. The prostate gland, V, surrounds its neck, and occupies a position behind and below the pubic arch, D, and in front of the rectum, W. The gland, V, being of a rounded form and dense structure, can be felt in this situation by the finger, passed upwards through the bowel. The prostate is suspended from the back of the pubic arch by the anterior true ligament of the bladder, and at its forepart, where the membranous portion of the urethra commences, this passes through the deep perinaeal fascia, X. The an­terior fibres of the levator ani muscle embrace the prostate on both its sides. Behind the base of the prostate, the ureter, K, is seen to enter the coats of the bladder obliquely, whilst the vas deferens, I, joined by the vesicula seminalis, L, penetrates the substance of the prostate, V, at its lower and back part, which lies in apposition with the rectum.

The rectum, W C, at its middle and upper parts, oc­cupies the hollow of the sacrum, A Q, and is behind the bladder. The lower third of the rectum, W, not being covered by the peritonaeum, is that part on which the various surgical operations are performed. At its upper three-fifths, the rectum describes a curve corre­sponding to that of the sacrum; and if the bladder be full, its convex back part presses the bowel against the bone, causing its curve to be greater than if the bladder were empty and collapsed. This fact requires to be borne in mind, for, in order to introduce a bougie, or to allow a large injection to pass with freedom into the bowel, the bladder should be first evacuated. The coccygeal bones, Q, continuing in the curve of the sa­crum, bear the rectum, W, forwards against the base of the bladder, and give to this part a degree of obli­quity upwards and backwards, in respect to the peri­naeum and anus. From the point where the prostate, V, lies in contact with the rectum, W, this latter curves downwards, and slightly backwards, to the anus, P. The prostate is situated at a distance of about an inch and a half or two inches from the anus--the distance varying according to whether the bladder and bowel be distended or not. [Footnote]

[Footnote: The distance between any two given parts is found to vary in different cases. "In subjects of an advanced age," Mr. Stanley remarks, "a deep perinaeum, as it is termed, is fre­quently met with. This may be occasioned either by an unusual quantity of fat in the perinaeum, or by an enlarged prostate, or by the dilatation of that part of the rectum which is contiguous to the prostate and bladder. Under either of these circumstances, the prostate and bladder become situated higher in the pelvis than naturally, and consequently at a greater distance from the perinaeum."--On the Lateral Operation of Lithotomy.]

The arteries of the bladder are derived from the branches of the internal iliac, S. The rectum receives its arteries from the inferior mesenteric and pudic. The veins which course upwards from the rectum are large and numerous, and devoid of valves. When these veins become varicose, owing to a stagnation of their circulation, produced from whatever cause, the bowel is liable to be affected with haemorrhoids or to assume a haemorrhagic tendency.

The pudic artery, S s, is a branch of the internal iliac. It passes from the pelvis by the great sciatic foramen, below the pyriformis muscle, and in company with the sciatic artery. The pudic artery and vein wind around the spine, E, of the ischium, where they are joined by the pudic nerve, derived from, T, the sacral plexus.