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the close relation of the ureter and the ovarian vessels must be borne in mind, while in ligaturing the inferior part of the external iliac it is the internal spermatic vessels and the ductus deferens which have to be avoided.

The common iliac veins lie mainly to the right of the corresponding arteries, the left vein, however, crossing behind the right artery to join its fellow to form the inferior vena cava.

The fact that the left common iliac vein passes behind the right common iliac artery to reach the vena cava would seem to afford a sufficient explanation for the much greater frequency with which thrombosis of the femoral vein is met with on the left side as compared with the right side.

The great vessels upon the posterior abdominal wall, along with the adjacent lymph vessels and glands, lie in the tela subserosa, and therefore within the general fascial envelope of the abdomen. Abscesses originating from the retroperitoneal lymph glands are, therefore, like perinephric abscesses, extra-peritoneal but intra-fascial; abscesses of vertebral origin, whether lumbar, iliac, or psoas, are, on the other hand, extra-fascial. Abscesses connected with the vermiform process are primarily intra-peritoneal; occasionally they ulcerate through the parietal peritoneum and burrow in the extra-peritoneal fat.

THE MALE PERINEUM.

The male perineum is a heart-shaped space, the osseous boundaries of which are the same as those which form the inferior aperture of the pelvis. A line drawn transversely across the perineum between the anterior part of the tuberosities of the ischium crosses the median plane, immediately in front of the anus, and divides the space into an anterior or urogenital triangle and a posterior or rectal triangle.

The urogenital triangle is subdivided into a superficial and a deep compartment by the inferior fascia of the urogenital diaphragm; in the superficial compartment is the root of the penis, which gives rise to a longitudinal fulness upon the surface. Anteriorly, the surface of the urogenital triangle is continued on to the scrotum, whilst laterally a distinct groove separates it from the medial surface of the thighs. The central point of the perineum (common tendon of the perineal muscles) is continuous with the centre of the base of the fascia of the urogenital diaphragm, and lies a finger's breadth in front of the anus. Immediately in front of it, and about 1 in. from the centre of the anus, is the posterior edge of the bulb of the corpus cavernosum urethra. The superficial compartment of the urogenital triangle is bounded below by the perineal fascia of Colles, which is attached posteriorly to the base of the fascia of the urogenital diaphragm, and laterally, on each side, to the margins of the pubic arch. Anteriorly, the fascia of Colles passes on to the scrotum, the penis, and spermatic funiculi, to become continuous with the fascia of Scarpa upon the anterior surface of the abdomen.

When the urethra is ruptured below the inferior fascia of the urogenital diaphragm, the course of infiltration of the extravasated urine is determined by these attachments; at first, therefore, the urine is confined within the superficial compartment, but gradually travels forwards, under the fascia of Colles, on to the inferior part of the anterior abdominal wall; it is prevented from passing into the front of the thigh by the attachment of Scarpa's fascia to the fascia lata, a little distal to the inguinal ligament.

The deep compartment of the urogenital division of the perineum corresponds to the interval between the inferior and superior fascia of the urogenital diaphragm. The most important structures which this compartment contains are the membranous part of the urethra, the bulbo-urethral glands, the internal pudendal vessels, and the artery to the bulb.

The membranous part of the urethra lies one inch behind the inferior border of the pubic symphysis. When this division of the urethra is ruptured, the extravasated urine, after filling the deep compartment, may reach the superficial compartment by bursting through the inferior fascia of the urogenital diaphragm where the vessels pierce it; or it may penetrate the superior fascia, infiltrate the perivesical

connective tissue and the space of Retzius, and ultimately ascend on the anterior abdominal wall between the fascia transversalis and the parietal peritoneum.

The bulbo-urethral glands, which lie immediately behind the membranous part o the urethra, are overlapped by the bulb of the urethra, from which they are separated by the inferior fascia of the urogenital diaphragm. The internal pudendal artery lies just within the margin of the pubic arch. The artery to the bulb runs transversely medially in. above the base of the urogenital diaphragm, 12 above the level of a line drawn from the front of the tuberosities to the central point of the perineum.

The male urethra measures about eight inches from the external to the internal orifice; the narrowest portion is at the external orifice; a second narrowing occurs at the urogenital diaphragm. It is behind these constrictions that a calculus is liable to become impacted. The most dependent part of the urethra is the bulbous portion, and it is in this situation that an organic stricture most frequently met with. The membranous part of the urethra, situated between the two fascia of the urogenital diaphragm, is surrounded by the sphincter urethra membranaceæ muscle, which, when thrown into spasm, may firmly grip an instrument as it is passed into the bladder. Rupture of the urethra from a fall on the perineum generally involves the bulbous portion. A false passage made during the passage of an instrument generally traverses the floor of the urethra at the urogenital diaphragm; to prevent this the point of the instrument should always be directed upwards, and the handle at the same time depressed as soon as the instrument is felt to encounter the resistance of the inferior fascia of the urogenital diaphragm. When the prostate is hypertrophied the prostatic part of the urethra is elongated, and the internal orifice may look directly forwards, while if the lateral lobes are unequally enlarged it may deviate laterally. Patients with prostatic hypertrophy are seldom able to empty the bladder completely, on account of the dependent well which exists behind the prostate.

Cystoscopic Examination of the Bladder.-On making a cystoscopic examination of the bladder special attention is paid to the trigone, as most of the pathological lesions are associated with this region. At its anterior angle is the internal urethral orifice, while at its postero-lateral angles are the small oblique slit-like orifices of the ureters, surrounded by a very slight lip-like elevation of the mucous membrane. At the base of the trigone the mucous membrane is raised into a smooth transverse ridge which stretches between the ureteric openings, with a slight forward convexity. The elevation is caused by a bundle of transverse muscular fibres, continuous with the longitudinal fibres of the ureters. The distance of the ureteric orifices from one another is rather more than an inch, while their distance from the internal urethral orifice is slightly less than an inch.

The urine is ejected into the bladder intermittently at intervals of a minute or so. During each ejection the ureteric orifice is seen to pucker up, and as it relaxes the gush of urine takes place in the form of a characteristic whirl "resembling an injection of glycerine into water." The mucous membrane of the trigone is closely connected with the subjacent muscular wall, so that it presents a smooth appearance; whereas over the rest of the bladder it is thrown into folds owing to the looseness of the submucous tissue. Further, the mucous membrane of the trigone presents a pink injection, while over the rest of the bladder it is of a pale straw colour. This contrast is due to the difference in the arrangement of the bloodvessels; over the trigone they are larger, more numerous, and form a close network: hence, when this surface is inflamed, the congested vessels form a continuous vascular layer. Over the rest of the bladder one sees, here and there in the mucous membrane, small segments of fine vessels giving off a cluster of short branches, the finer anastomoses of which are not visible when the mucous membrane is healthy.

The form and shape of the trigone in women may be distorted by prolapse of the bladder, by alterations in the size and position of the cervix, and by the presence of fibroids. In the male, distortion is usually due either to the enlargement of the prostate or to disease of the vesiculæ seminales.

When the normal bladder is comfortably filled, the bladder walls appear almost smooth, but when the bladder contracts the delicate muscular trabecule

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become visible through the mucous membrane.

When the bladder is hypertrophied as the result of urinary obstruction the muscular trabeculæ become greatly hypertrophied, and stand out prominently, even when the bladder is full. The spaces between the trabeculae may become so deeply pitted as to lead to the formation of little pockets, known as false diverticula.

THE PROSTATE.

The operation of prostatectomy has proved so successful in removing urinary complications associated with enlargement of the prostate that a fresh impetus has been given to the study of the anatomy of the gland from the surgical point of view. With the body erect the base of the prostate lies in a horizontal plane at the level of the middle of the symphysis pubis, while its apex liesin. behind and below the sub-pubic angle. It follows, therefore, that the vesical orifice and the base of the prostate are within easy reach of the finger introduced through a supra-pubic cystotomy incision. The anterior surface of the prostate lies about

in. behind the pubes, to which it is connected by the pubo-prostatic ligaments. Above those ligaments is the space of Retzius, occupied by fatty tissue which passes upwards in front of the anterior wall of the bladder, between the umbilical arteries, as far as the umbilicus, while laterally it extends on each side, between the peritoneum and pelvic fascia, as far back as the hypogastric arteries. The posterior surface of the prostate is related to that part of the rectal ampulla immediately above the anal canal, and is therefore accessible to palpation per rectum. Between the rectum and the posterior part of the sheath of the prostate (formed by the recto-vesical layer of pelvic fascia) is a loose cellular interval, which is taken advantage of in the operation of excision of the rectum, and in exposing the posterior surface of the prostate in the operation of perineal prostatectomy. The lateral surfaces of the prostate cannot be felt through the rectum; they are related to the anterior or pubo-rectal fibres of the levatores ani, from which they are separated by the lateral portion of the fascial envelope of the gland.

The prostate substance is made up of branching tubular glands supported by a fibro-muscular stroma. The gland tissue is most abundant in the posterior and lateral aspects of the organ; anteriorly the stroma is more abundant and extends backwards from the capsule to the urethra to form a sort of anterior commissure. By the term "capsule" of the prostate is understood the immediate or proper envelope of the gland; this envelope consists of parallel layers of fibromuscular tissue, continuous with, and forming part of, the stroma of the organ. In some instances it is so thin that the gland tissue reaches almost to its surface, while in other instances it is so thick as to deserve to be regarded as forming the cortical portion of the gland. By the term "sheath" of the prostate is meant the fibrous envelope derived from the pelvic fascia; the veins of the pudendal plexus lie between its lamellæ.

In what is known as "senile" hypertrophy of the prostate the organ may be uniformly enlarged, or the enlargement may affect chiefly one or other of the lateral lobes, one or both of which may enlarge more particularly in an upward direction so as to project into the bladder. This intra-vesical overgrowth may take the form either of a more or less pedunculated projection, situated immediately behind the internal urethral orifice, or it may surround the orifice to form a prominent ring-like elevation. As the intra-vesical growth enlarges, it makes its way towards the bladder within the ring of the sphincter vesicæ, and, having pushed before, or separated, the internal longitudinal fibres of the bladder, it comes ultimately to be separated from the cavity of the bladder by mucous membrane only. In the operation of supra-pubic prostatectomy the true capsule of the prostate is at once reached by simply tearing through the mucous membrane immediately behind the vesical orifice. By keeping close to the capsule, the entire organ, including the capsule, may be enucleated from its sheath. As the latter is markedly thicker and denser in the hypertrophied than in the normal prostate, this enucleation can be accomplished without injuring the veins of the pudendal plexus. As a rule, the only part where any difficulty in the enucleation is encountered is anteriorly, where the capsule is more intimately connected with the sheath by the interposition of a layer of striated longitudinal muscular fibres which pass from the urethra to be continuous with the outer

longitudinal fibres of the bladder. In "total" prostatectomy, practically the whole of the prostatic urethra is removed along with the gland. In some instances, instead of removing the entire prostate and its capsule along with the prostatic urethra, the surgeon, by working within the capsule, is able to enucleate each lateral glandular mass either separately or united to its fellow in the form of a horse-shoe shaped mass, the urethra and the anterior commissure being left more or less intact. The cavity, which is left behind after the removal of the prostate, at once contracts owing to the approximation of the bladder and rectum antero-posteriorly, and of the levatores ani at the sides.

In perineal prostatectomy the posterior surface of the prostate is exposed by making a horse-shoe shaped incision with the convexity reaching forwards to a point immediately behind the bulb; at the sides, the incision sinks into the ischio-rectal fossæ, its extremities ending at the anterior part of the ischial tuberosities (Fig. 1108). After reflecting the skin and subcutaneous tissue, the incision is carried through the central point of the perineum.

The bulb, the superficial transverse perineal muscles, and the inferior fascia of the urogenital diaphragm are now drawn forwards, and the fibres of the recto-urethral muscle (which connect the anterior wall of the rectal ampulla with the sphincter urethra) are divided; this allows the anal canal and the inferior end of the rectum to be retracted backwards. The dissection is now carried in a forward direction, between the anterior borders of the levatores ani, towards the prostate, so as to strike the loose non-vascular space which intervenes between the posterior part of the prostatic sheath and the thin fascia outside the muscular wall of the rectum. The posterior surface of the prostate, covered by its true capsule, is reached by incising the fascial sheath. The prostate, along with its true capsule and the urethra, may either be enucleated entire from the sheath, or the true capsule may be incised as well as the sheath, and the adenomatous masses removed separately. The operation is greatly facilitated by pulling the prostate down into the wound by a special retractor (Young) inserted into the bladder through a median incision into the floor of the membranous part of the urethra.

The epididymis, which can be felt, as an elongated curved body applied vertically to the posterior margin of the testis, is especially involved in gonorrhoeal and tubercular infections of the testis. Occupying the posterior part of the spermatic funiculus is the ductus deferens, which, when grasped between the finger and thumb, feels like a piece of whip-cord. The spermatic veins form a plexus in the substance of the funiculus, known as the pampiniform plexus; a varicose condition of these veins gives rise to the condition known as varicocele. In operating for varicocele the veins are reached by dividing, in succession, all the coverings of the funiculus; the deepest covering, viz., the internal spermatic fascia, derived from the fascia transversalis, forms a well-marked fibrous envelope which immediately surrounds the veins and other constituents of the funiculus. Besides the internal spermatic artery, the testis receives its blood supply from the artery accompanying the ductus deferens and from the external spermatic branch of the inferior epigastric.

The marked swelling which attends edema and hæmatoma of the scrotum is due to the loose and delicate character of the cellular tissue which occupies the space between the dartos muscle and the subjacent membrane derived from the intercolumnar fascia.

The anus is situated in the rectal division of the perineum about 1 in. in front of and below the tip of the coccyx. The skin around the orifice is pigmented and thrown into radiating folds. The painful linear crack or ulcer, known as fissure of the anus, generally occupies one of the furrows at the posterior margin of the anus. The skin of the anus is provided with large sebaceous and sweat glands, which are occasionally the site of small and very painful anal abscesses.

On making a rectal examination it will be observed that the finger, before it reaches the cavity of the rectum, traverses the narrow or sphincteric portion of the rectum, appropriately named by Symington the anal canal. This canal, which is directed from below upwards and forwards, extends from the anal orifice to the ampulla of the rectum; it is from one to one and a half inches in length; its upper end is on a level with the medial borders of the pubo-rectal portions of the levatores ani.

External hæmorrhoids are developed from the anal folds situated outside the white line corresponding to the muco-cutaneous junction; internal piles are developed from the veins of the mucosa at the upper part of the anal canal.

In the superior half of the anal canal are the rectal columns of Morgagni. According to Ball, fissure of the anus is generally caused by the tearing downwards of one of the posterior rectal sinuses (Fig. 1107) during the passage of a scybalous mass.

According to Birmingham, the pubo-coccygeal fibres of the levator ani close the superior part of the anal canal, whilst the external sphincter closes the remaining part. The internal sphincter, according to the same author, acts probably as a detrusor, its use being to empty the anal canal completely Longitudinal after the passage of the fæcal mass.

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FIG. 1107.-THE INTERIOR OF THE ANAL CANAL AND INFERIOR PART OF THE RECTUM.

fibres of
rectum

Part of
levator ani

Internal sphincter

Anal canal

Ischio-rectal Fossa. -The apex of the ischiorectal fossa (Fig. 1108), formed by the attachment of the inferior fascia of the pelvic diaphragm (anal fascia) to the obturator portion of the parietal pelvic fascia, is directed upwards towards the pelvis, and lies 2 in.

from the surface. The Showing the rectal columns of Morgagni and the rectal sinuses between their medial wall of the fossa inferior ends. The columns were more numerous in this specimen than usual. (From Birmingham.) is bounded by the levator ani and coccygeal muscles covered by the inferior fascia of the pelvic diaphragm (Fig. 1108); the lateral wall by the obturator internus muscle covered by the obturator fascia. An abscess in the ischio-rectal fossa should be opened early, otherwise it is liable to burst through the medial wall into the rectum; should it open also upon the skin surface a complete " fistula in ano" is formed. When a "fistula in ano" results from the bursting of a submucous abscess of the anal canal the track of the fistula runs either medial to or through the fibres of the internal and external sphincter muscles, and the external or skin opening is, as a rule, close to the anus, while the internal opening is generally within the upper end of the anal canal. Occasionally the ischio-rectal abscess perforates the levator ani towards the apex of the fossa; it then burrows into the peri-rectal cellular tissue of the pelvis, and opens into the ampulla of the rectum. In other cases, again, the abscess starts in the peri-rectal tissue internal to the levator ani, and either bursts into the rectal ampulla or through the levator ani into the ischio-rectal fossa, and so reaches the surface. Or the pus may burrow between the rectum and coccyx, whence it may pass outwards through the greater sciatic foramen, behind the parietal pelvic fascia, into the buttock; or, by piercing the visceral layer of the pelvic fascia, may reach the tela subserosa of fatty tissue of the pelvis and ascend in it to form an iliac abscess.

MOOD CO

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mucous membrane

Rectal columns of Morgagni

Rectal sinuses

The lymph vessels from the skin of the anus pass along the perineo-femoral folds to the most medial glands of the groin, both superficial and deep subinguinal. According to Poirier and Cunéo, those from the region of the white line end in the hypogastric glands which lie in front of the hypogastric artery, while those which issue from the mucous membrane of the upper part of the anal canal and the rectum proper traverse a few minute glands (ano-rectal glands of Gerota) placed between the muscular and fibrous coats of the rectum, along the superior hæmorrhoidal vein and its two branches, and pass thence to the sacral glands which lie internal to the anterior sacral foramina.

Digital Examination of Rectum.-In making a rectal examination the finger should be carried forwards from the tip of the coccyx so as to enter the anus from behind. The finger is then gently pressed upwards and slightly forwards through the sphincteric

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