Surgical Anatomy Part 35

[Ill.u.s.tration: Abdomen and leg, showing bone, blood vessels and other internal organs.]

Plate 47.

COMMENTARY ON PLATES 48 & 49.

THE RELATIVE ANATOMY OF THE MALE PELVIC ORGANS.

As the abdomen and pelvis form one general cavity, the organs contained in both regions are thereby intimately related. The viscera of the abdomen completely fill this region, and transmit to the pelvic organs all the impressions made upon them by the diaphragm and abdominal walls.

The expansion of the lungs, the descent of the diaphragm, and the contraction of the abdominal muscles, cause the abdominal viscera to descend and compress the pelvic organs; and at the same time the muscles occupying the pelvic outlet, becoming relaxed or contracted, allow the perinaeum to be protruded or sustained voluntarily according to the requirements. Thus it is that the force originated in the muscular parietes of the thorax and abdomen is, while opposed by the counterforce of the perinaeal muscles, brought so to bear upon the pelvic organs as to become the princ.i.p.al means whereby the contents of these are evacuated. The abdominal muscles are, during this act, the antagonists of the diaphragm, while the muscles which guard the pelvic outlet become at the time the antagonists of both. As the pelvic organs appear therefore to be little more than pa.s.sive recipients of their contents, the voluntary processes of defecation and micturition may with more correctness be said to be performed rather for them than by them. The relations which they bear to the abdomen and its viscera, and their dependence upon these relations for the due performance of the processes in which they serve, are sufficiently explained by pathological facts.

The same system of muscles comprising those of the thorax, abdomen and perinaeum, performs consentaneously the acts of respiration, vomiting, defecation and micturition. When the spinal cord suffers injury above the origin of the phrenic nerve, immediate death supervenes, owing to a cessation of the respiratory act. Considering, however, the effect of such an injury upon the pelvic organs alone, these may be regarded as being absolutely excluded from the pale of voluntary influence in consequence of the paralysis of the diaphragm, the abdominal and perinaeal muscles. The expulsory power over the bladder and r.e.c.t.u.m being due to the opposing actions of these muscles above and below, if the cord be injured in the neck below the origin of the phrenic nerve, the inferior muscles becoming paralysed, the antagonism of muscular forces is thereby interrupted, and the pelvic organs are, under such circ.u.mstances, equally withdrawn from the sphere of volition. The antagonism of the abdominal muscles to the diaphragm being necessary, in order that the pelvic viscera may be acted upon, if the cord be injured in the lower dorsal region, so as to paralyse the abdominal walls and the perinaeal muscles, the downward pressure of the diaphragm alone could not evacuate the pelvic organs voluntarily, for the abdominal muscles are now incapable of deflecting the line of force backwards and downwards through the pelvic axis; and the perinaeal muscles being also unable to act in agreement, the contents of the viscera pa.s.s involuntarily. Again, as the muscular apparatus which occupies the pelvic outlet acts antagonistic to the abdomen and thorax, when by an injury to the cord in the sacral spine the perinaeal apparatus alone becomes paralysed, its relaxation allows the thoracic and abdominal force to evacuate the pelvic organs involuntarily. It would appear, therefore, that the term "paralysis" of the bladder or r.e.c.t.u.m, when following spinal injuries, &c. &c. means, or should mean, only a paralytic state of the abdomino-pelvic muscular apparatus, entirely or in part. For, in fact, neither the bladder nor r.e.c.t.u.m ever acts voluntarily per se any more than the stomach does, and therefore the name "detrusor" urinae, as applied to the muscular coat investing the bladder, is as much a misnomer (if it be meant that the act of voiding the organ at will be dependent upon it) as would be the name "detrusor"

applied to the muscular coat of the stomach, under the meaning that this were the agent in the spasmodic effort of vomiting.

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 r.e.c.t.u.m, 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 cus.h.i.+on. 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 s.e.xes. When distended, its long axis will be found to coincide with a line pa.s.sing from a point midway between the navel and p.u.b.es 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 rec.u.mbent, the bladder recedes somewhat from the p.u.b.es, 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 p.u.b.es, 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 r.e.c.t.u.m, 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 r.e.c.t.u.m. 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 r.e.c.t.u.m. The serous pouch descends lower in some bodies than in others; but in all there exists a s.p.a.ce, of greater or less dimensions, between it and the prostate, V, whereat the base of the bladder is in direct apposition with the r.e.c.t.u.m, 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." 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 s.p.a.ce. The prostate gland, V, surrounds its neck, and occupies a position behind and below the pubic arch, D, and in front of the r.e.c.t.u.m, W. The gland, V, being of a rounded form and dense structure, can be felt in this situation by the finger, pa.s.sed 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 pa.s.ses 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 r.e.c.t.u.m.

The r.e.c.t.u.m, 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 r.e.c.t.u.m, W, not being covered by the peritonaeum, is that part on which the various surgical operations are performed. At its upper three-fifths, the r.e.c.t.u.m 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 pa.s.s with freedom into the bowel, the bladder should be first evacuated. The coccygeal bones, Q, continuing in the curve of the sacrum, bear the r.e.c.t.u.m, 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 a.n.u.s. From the point where the prostate, V, lies in contact with the r.e.c.t.u.m, W, this latter curves downwards, and slightly backwards, to the a.n.u.s, P. The prostate is situated at a distance of about an inch and a half or two inches from the a.n.u.s--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 quant.i.ty of fat in the perinaeum, or by an enlarged prostate, or by the dilatation of that part of the r.e.c.t.u.m which is contiguous to the prostate and bladder. Under either of these circ.u.mstances, 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 r.e.c.t.u.m receives its arteries from the inferior mesenteric and pudic. The veins which course upwards from the r.e.c.t.u.m 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 a.s.sume a haemorrhagic tendency.

The pudic artery, S s, is a branch of the internal iliac. It pa.s.ses 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. The artery, in company with the nerve and vein, re-enters the pelvis by the small sciatic foramen, and gets under cover of a dense fibrous membrane (obturator fascia), between which and the obturator muscle, it courses obliquely downwards and forwards to the forepart of the perinaeum. At the place where the vessel re-enters the pelvis, it lies removed at an interval of an inch and a half from the perinaeum, but becomes more superficial as it approaches the subpubic s.p.a.ce, N. The levator ani muscle separates the pudic vessels and nerves from the sides of the r.e.c.t.u.m and bladder. The princ.i.p.al branches given off from the pudic artery of either side, are (1st), the inferior hemorrhoidal, to supply the lower end of the r.e.c.t.u.m; (2nd), the transverse and superficial perinaeal; (3rd), the artery of the bulb; (4th), that which enters the corpus cavernosum of the p.e.n.i.s, N; and (5th), the dorsal artery of the p.e.n.i.s. [Footnote] The branches given off from the pudic nerve correspond in number and place to those of the artery. Having now considered the relations of the pelvic organs in a lateral view, we are better prepared to understand these relations when seen at their perinaeal aspect.

[Footnote: The pudic artery, or some one of its branches, occasionally undergoes marked deviations from the ordinary course. In Mr. Quain's work, ("Anatomy of the Arteries,") a case is represented in which the artery of the bulb arose from the pudic as far back as the tuber ischii, and crossed the line of incision made in the lateral operation of lithotomy. In another figure is seen a vessel ("accessory pudic"), which, pa.s.sing between the base of the bladder and the levator ani muscle, crosses in contact with the left lobe of the prostate.]

DESCRIPTION OF PLATES 48 & 49.

PLATE 48.

A. The anterior superior iliac spine.

B. The anterior inferior iliac spine.

C. The acetabulum; c, the ligamentum teres.

D. The tuber ischii.

E. The spine of the ischium.

F. The pubic horizontal ramus.

G. The summit of the bladder covered by the peritonaeum.

H. The femoral artery.

I. The femoral vein.

K. The anterior crural nerve.

L. The thyroid ligament.

M. The spermatic cord.

N. The corpus cavernosum p.e.n.i.s; n, its artery.

O. The urethra; o, the bulbus urethrae.

P. The sphincter ani muscle.

Q. The coccyx.

R. The sacro-sciatic ligament.

S. The pudic artery and nerve.

T. The sacral nerves.

U. The pyriformis muscle, cut.

V. The gluteal artery.

W. The small gluteus muscle.

[Ill.u.s.tration: Abdomen, showing bone, blood vessels and other internal organs.]

Plate 48

PLATE 49.

A. The part of the sacrum which joins the ilium.

B. The external iliac artery, cut across.

C. The upper part of the r.e.c.t.u.m.

D. The ascending pubic ramus.