928 



PERINEUM. 



towards the anus ; the density of the triangular 

 ligament of the urethra impedes its passage 

 into the pelvis ; whilst the loose connection 

 between the superficial fascia and the subjacent 

 structures in front, the remarkable laxity of the 

 dartos, and the continuity of this latter with 

 the superficial fascia of the perineum on the 

 one hand, and with that of the abdomen on 

 the other, are so many circumstances inviting 

 the stream to the scrotum, the penis, and the 

 walls of the abdomen. The promptest treat- 

 ment is demanded to remedy mischief such as 

 has been described. A free division of the 

 integuments and fascia in the perineum over 

 the seat of rupture, for the purpose of giving 

 the urine vent and putting a stop to further 

 effusion, becomes indispensable, and without 

 this measure all others must be unavailing. 



The laxity of the superficial fascia as it 

 approaches the scrotum should deter the sur- 

 geon from commencing his cutaneous incisions 

 in the lateral operation of lithotomy too far 

 forwards, lest urinary infiltration should ensue ; 

 and the density of the same structure in other 

 situations indicates an early incision for the 

 release of matter imprisoned beneath it. 



For a description of the posterior or anal 

 division of the perineum, including the ischio- 

 rectal fossae and the neighbouring fibrous mem- 



o o 



branes, the reader is now referred to the arti- 

 cle ANUS, where all the structures connected 

 with the lower extremity of the rectum are 

 described in detail. It should be borne in 

 mind, however, that some branches of arteries 

 (the inferior or external hemorrhoidal) pass 

 across the ischio-rectal fossae, entangled in the 

 fat which occupies those excavations. The 

 inferior hemorrhoidal vessels are usually three 

 in number at each side; they derive their origin 

 from the internal pudic artery, as it lies be- 

 neath the obturator fascia ; their destination is 

 the lower extremity of the gut and its appen- 

 dages, and one of them (the most anterior) 

 gains the front of the intestine to anastomose 

 with a similar vessel from the opposite side, 

 and with branches of the transversalis perinei 

 also. The inferior hemorrhoidal vessels are 

 remarkably tortuous and rather uncertain in 

 their course ; the anterior of them is sometimes 

 divided in the lateral or bilateral operations of 

 lithotomy, a circumstance which has led to this 

 cursory notice of their anatomy. 



When the superficial fascia has been dis- 

 placed, many new parts become apparent in the 

 genito-urinary division of the perineum ; a 

 quantity of loose adeps and also a very thin 

 glistening fibrous expansion which adheres 

 closely to the subjacent muscles and obscures 

 the dissection, must, however, be carefully re- 

 moved before the deeper structures are satis- 

 factorily displayed. The central tendinous 

 point of the perineum, the superficial perjneal 

 bloodvessels and nerves, the transversalis peri- 

 nei artery with its accompanying veins and 

 nerves at each side respectively, the urethra 

 itself, still however obscured by the accelera- 

 tores urinae muscles, the crura penis, each 

 partly enveloped by the erector penis muscle, the 



transversi perinei muscles, and two small trian- 

 gular spaces bounded by muscles and placed 

 one at either side of the urethral prominence, 

 are the principal objects which come into view. 



The central tendinous point of the perineum 

 is situated in the middle line, equidistant from 

 the anus and the bulb of the urethra. It is a 

 common point of insertion to many muscles ; 

 thus the superficial sphincter of the anus can 

 be fairly traced to this spot, and so can many 

 fibres of the accelerators urinae, the transversi 

 perinei, the levatores ani, and Wilson's mus- 

 cles. Here muscular fibres from opposite sides 

 of the perineum become blended with each 

 other; here, too, those from before and those 

 from behind are intermixed, and some even 

 descend from within the pelvis to identify 

 themselves in this place with others which are 

 subcutaneous. 



The superficial perineal artery (the perineal 

 artery of some anatomists), though not a large 

 vessel, yet takes a lengthened and very regular 

 course. Its origin is from the internal pudic 

 artery at some little distance behind the trans- 

 versus perinei muscle, whilst the parent trunk 

 is still under cover of the obturator fascia ; it 

 immediately pierces that membrane, and like- 

 wise very generally passes through the base of 

 the triangular ligament of the urethra. The 

 artery next curves around the transversus peri- 

 nei muscle lying on its superficial surface and 

 running across its fibres. The vessel then in- 

 clines forwards and inwards through the trian- 

 gular interval between the accelerator urinae 

 and the erector penis muscles, until at length it 

 reaches the scrotum, and assuming the name 

 of " the arteria septi," it terminates in a free 

 anastomosis with the other arteries supplying 

 the envelopes of the testicles. The superficial 

 perineal artery lies deep posteriorly, but its 

 position becomes very superficial as it ap- 

 proaches the scrotum ; its branches are distri- 

 buted freely to the muscles and integuments, 

 and they likewise anastomose internally with 

 branches from the corresponding artery of the 

 opposite side, and externally with superficial 

 branches from the thigh. Two veins accom- 

 pany this artery; they are frequently dilated 

 and tortuous in front, and in certain diseased 

 conditions of the testicle or its coverings they 

 sometimes form a complicated net-work in the 

 scrotum. 



The inferior or superficial division of the 

 pudic nerve (" the perineal nerve" of many 

 authors) follows pretty nearly the course of 

 these vessels; like the artery, it is destined for 

 the scrotum, where it terminates by several 

 long and very fine branches, after supplying in 

 its progress numerous twigs to the transversus 

 perinei, accelerator urinae, levator ani, and 

 erector penis muscles. One very remarkable 

 branch of this nerve (the bulbo-urethral of 

 Cruveilhier) may be traced fairly into the bulb, 

 whilst another (the external perineal of the 

 same anatomist) runs superficially along the 

 lateral part of the region, reinforcing and 

 anastomosing with the perineal cutaneous 

 branch of the lesser sciatic nerve. 



