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 laminw 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 pelvds 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 projectin,„a 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 edge 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 usually failed, for so deeply do the pudic vessels run, and so firmly bound down are they by the triangular ligament and the obturator fascia, that the ligature, as commonly applied, has proved useless in the hands of even the most dexterous surgeons. The open mouth of the artery may, however, in such cases be often secured by the aid of a curved needle carried deeply into the wound, and some practitioners (amongst the number M. Itou x) have sticceeded by the same means in tying, the pudic artery itself in the vicinity of the tuber ischii, a pro ceeding attended with complete success. The
judicious application of pressure to the bleeding point by an apparatus so constructed as to plug the avound at the same time that it permits the urine to escape freely, has been also followed by satisfactory results. The same principles of treatment are applicable to hemorrhage from accidental vvounds of the arteries of the bulb in lithotomy.
On dividing the triangular ligament of the urethra the dissector arrives at the deep com partment of the anterior division of the peri neum, hilt to examine its contents with advan tage he requires a section of the pelvis, such as that advised in a fornier part of this article. This compartment is limited superiorly or towards the abdomen by the recto-vesical layer of the pelvic fascia; inferiorly or towards the surface by the back of the triangular liga ment of the urethra ; and posteriorly by the rectum ; its shape is somewhat triangular, and it contains NVilson's muscles, many fibres of the levatores ani, a part of the membranous por tion of the urethra, the prostate gland, a plexus of veins excessively developed in some sub jects, and at times also an irregular artery justly dreaded by the lithotomist.
Wilson's muscles (the compressores urethrm) are two triangular fleshy fasciculi, which arise from the back of the symphysis pubis, each by a narrow tendon ; their point of attachment is about one-eighth of an inch beneath the ante rior true ligament of the bladder, and the same distance above the lower margin of the cartila ginous arch of the pubis. The two muscles, expanding as they descend, separate from each other at the membranous portion of the urethra, and passing on4 on each side of that part of the canal they again unite beneath it in a sort of tendinous raph6, which extends from the pros tate gland to the bulb; many of their fibres may be likewise traced to the central tendinous point of the perineum. A cellular interstice inter venes between the two muscles at their origin, and from the levatores ani they are separated at each side respectively by cellular tissue and some small veins. NVilson's muscles may ele vate and compress the urethra so as to close the canal ; their influence in catheterism is decided and has been already discussed; one of them, the left, is divided in the lateral, and both are cut in the bilateral operation of litho tomy. In some subjects NVilson's muscles are absent, or rather they are inseparable from the levatores ani; hut in such cases the anterior fibres of these latter muscles surround the ure thra, perform all the offices assigned to the compressores uretlinr, and are similarly circum stanced as regards operations on the perineum. The recto-urethral space, but partially seen so long as the triangular ligament of the urethra remains in situ, becomes fully exposed after the division of that fibrous septum. This space results from the inclination backwards of the lower extremity of the rectum, whilst the urethra inclines forwards through the arch of the pubis; its form is triangular, the base at the integuments of the perineum, the ape_x at the prostate gland, the membranous and the bulbous portions of the urethm constituting its anterior wall, and the rectum bounding it pos teriorly. In cutting from the integuments to the urethra through the recto-urethral triangle, the anatomist encounters, first, the superficial perineal fascia; next, the extremities of the several muscles which meet and are confounded with each other at the ceniral tendinous point of the perineum, and also the small arterial anastomosis situated in the same locality, still deeper the peaked prolongation of the trian gular ligament ; and, lastly, Wilson's muscles at their junction beneath the urethra.