THE MALE PERINEUM. 1427 



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 de'ferens 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 retro- 

 peritoneal 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. 



RThe male perineum is a heart-shaped space, the osseous boundaries of which are 

 5 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 con- 

 tinuous with the centre of the base of the fasciae 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 urethrse. 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 fa-scia 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 fascise 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 



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