PERINEUM. 



931 



fan-shaped, appearing expanded at the urethra 

 and contracted at their origin from the bone, 

 and they are believed to have the power of 

 compressing the urethra so as to close the canal. 

 Notwithstanding the accurate descriptions of 

 Mr. Guthrie, many excellent anatomists have 

 failed to demonstrate the exact arrangement of 

 fleshy fibres which he has remarked, but the 

 majority incline to the opinion that the peculiar 

 reddish material in question is of a muscular 

 nature. 



The arteries of the bulb (one at either side) 

 spring from the internal pudic after those ves- 

 sels have arrived at the triangular ligament of 

 the urethra, and whilst they are overlapped by 

 the crura penis. Interposed between the la- 

 minae, and situated about a quarter of an inch 

 above the base of the triangular ligament, the 

 artery of the bulb runs nearly transversely in- 

 wards, and near the urethra divides into two 

 branches, of which one is small and destined for 

 Cowper's gland, whilst the other is of large 

 size and perforates the bulb to supply the 

 corpus spongiosum urethra. The arteries of 

 the bulb are of considerable magnitude, parti- 

 cularly after puberty, so that they bleed pro- 

 fusely when wounded ; they retract between the 

 layers of the triangular ligament when divided, 

 and this added to the narrowness of the peri- 

 neum in front, and to the distance from the 

 surface at which they are placed, renders it diffi- 

 cult for the surgeon to secure their cut extremi- 

 ties or otherwise to control their hemorrhage. 

 The consequences of such an accident may 

 prove speedily fatal ; extreme care must there- 

 fore be taken to protect these vessels from the 

 knife during lithotomy. 



The artery of the bulb is endangered in the 

 second period of the lateral operation whilst the 

 surgeon cuts into the membranous portion of 

 the urethra to lay bare the groove of the staff. 

 The knife should be introduced into the urethra 

 behind the bulb, and below and behind the 

 course of the artery, and little or none of the 

 triangular ligament except the posterior lamina 

 where it invests the membranous portion of the 

 urethra, should be divided in this incision, for 

 the vessel requiring protection lies about one 

 quarter of an inch above the base of the liga- 

 ment, and therefore none but the very lowest 

 fibres of that structure can be cut with impu- 

 nity ; in short the incision must be made into 

 the membranous portion of the urethra as it 

 lies behind the triangular ligament, and the 

 bulb must be studiously avoided. Irregularities 

 in the direction of these arteries calculated to em- 

 barrass the operating surgeon are occasionally 

 encountered ; arising sometimes prematurely 

 from the pudic, they ascend very obliquely to 

 the bulb; and again, although given off from 

 the pudic at the usual place, they now and then 

 take a curved course to their destination, the 

 convexity of the curvature looking downwards 

 and backwards ; when either of these varieties 

 occurs, the vessels in question run much closer 

 to the base of the triangular ligament than 

 usual, and are therefore imminently endangered 

 in lithotomy. 



The internal pudic arteries in their third 



stage belong to the perineum. This stage com- 

 mences where the vessel enters the pelvis at the 

 lesser sciatic notch, and ends at the ramus of 

 the pubis, where it divides into its terminating 

 branches. Posteriorly the trunk of the internal 

 pudic is (strictly speaking) placed outside the 

 precincts of the perineum, being separated from 

 the ischio-rectal fossa by the obturator fascia, 

 but it runs so close to that part of the region, 

 and sends so many of its branches through the 

 intermediate partition to lose themselves in pe- 

 rineo, that its description may be here legiti- 

 mately given. At the commencement of its 

 third stage, the internal pudic is interposed be- 

 tween the obturator fascia and the obturator 

 internus muscle, the muscle separating it from 

 the bone, whilst the falciform process of the 

 great sciatic ligament covers the artery infe- 

 riorly : in this situation it lies at a great depth 

 from the surface, being upwards of an inch 

 above the level of the tuber ischii, and at least 

 two inches and a-half distant from the integu- 

 ment; it here also describes a slight curve in- 

 clining upwards, forwards, and inwards, towards 

 the edge of the ramus of the ischium. In the 

 latter part of its third stage the internal pudic 

 artery insinuates itself between the laminae of 

 the triangular ligament, and after continuing 

 thus for some distance it at length perforates 

 the superficial layer, places itself between the 

 crus penis and the ramus of the pubis, and there 

 finally divides into the artery of the crus and 

 the dorsal artery of the penis. 



On entering the pelvis the pudic arteries of 

 opposite sides are widely separated from each 

 other, but in the neighbourhood of the pubis 

 they gradually converge until their ultimate 

 branches meet on the dorsum of the penis; their 

 position likewise becomes more and more su- 

 perficial as they proceed. 



In the early part of its third stage the pudic 

 artery is accompanied by the trunk of the inter- 

 nal pudic nerve, and afterwards for a short dis- 

 tance by both the branches of that nerve ; but 

 the deeper of the two (viz. the dorsalis penis) 

 alone continues in relation with the artery in 

 the latter part of its course. Two veins accom- 

 pany the artery throughout. 



The position of the internal pudic vessels 

 exposes them to injury in the lateral operation 

 of lithotomy; but if their relations be considered 

 it will appear that the danger of hemorrhage 

 from this source has been much exaggerated. 

 The falciform process of the great sciatic liga- 

 ment, the crus penis, the projecting edges of 

 the bones, and the obturator fascia afford these 

 vessels so much protection from below that the 

 operator seldom wounds them in cutting into 

 the bladder, nor is such an injury possible un- 

 less the edge of the knife be lateralized to an 

 extreme degree ; but if the knife be carelessly 

 withdrawn from the bladder, they certainly 

 incur considerable risk, for in that step of the 

 operation a layer of fibrous membrane alone 

 protects the vessels, and the convex ed^e of the 

 instrument, if directed unduly outwards, might 

 readily enough divide them. When such an 

 accident has occurred, all attempts to tie the 

 bleeding artery in the ordinary manner have 



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