ILIAC ARTERIES. 



835 



and the anterior sacro-sciatic ligament, passing 

 between the pyriformis and the ischio-coccygeus 

 muscles, and having the ischiatic artery and 

 sciatic nerve both external and posterior - to it. 

 Its second stage is situate without the pelvis ; 

 it is usually its shortest one, lasting only while 

 the artery is crossing the extremity of the 

 spinous process of the ischium, and not exceed- 

 ing an inch in length ; it is here situate behind 

 and above the spinous process and the anterior 

 or lesser sciatic ligament ; it is covered poste- 

 riorly by the superior edge of the posterior liga- 

 ment and by the glutens maximus muscle ; it 

 is internal to both the ischiatic artery and 

 sciatic nerve, and it is crossed posteriorly by 

 the coccygean branch of the former. 



The third stage of the artery is its longest 

 and most important one ; during it the vessel 

 is situate within the skeleton of the pelvis, 

 though not within the pelvis, in the ordinary 

 sense of the phrase, i. e. within its visceral ca- 

 vity, being excluded therefrom by the struc- 

 tures which form its floor; it lies along the 

 inside of the tuberosity of the ischium and the 

 rami of the ischium and pubis, and its course and 

 relations being different at the posterior and an- 

 terior parts of the stage, they may with advan- 

 tage be considered separately. In the posterior 

 part, or as far forward as the anterior extremity 

 of the tuberosity or the base of the triangular 

 ligament of the perinaeum, the artery descends ; 

 in the anterior it ascends ; in the posterior it is 

 situate in the outer wall of the space which in- 

 tervenes between the inside of the tuberosity of 

 the ischium and the rectum the ischio-rectal 

 space. This space is cuneiform, its base below, 

 toward the surface ; its apex above, toward the 

 pelvis ; its inner wall is formed by the levator ani 

 and the dense thin expansion by which the mus- 

 cle is covered externally or interiorly, its outer 

 by the obturator fascia attached inferiorly to the 

 edge of the great sacro-sciatic ligament and of its 

 falciform process, and by the obturator muscle : 

 the space is occupied by,a mass of adipose cel- 

 lular structure, traversed by some branches of 

 the pudic vessels and nerves. In a canal in 

 the obturator fascia the artery is contained 

 through the posterior part of the third stage ; by 

 some it is maintained to be between the fascia 

 and the muscle, in a sort of canal formed inter- 

 nally by the fascia, externally by the muscle 

 and tuberosity, and inferiorly by the great 

 sciatic ligament ; but this is not correct ; the 

 vessel being in the fascia, and not external to 

 it ; the line of its course is convex downward, 

 about an inch and a half from the under surface 

 of the tuberosity of the ischium at its most de- 

 pending part, and from two to two and a half 

 inches from the surface, this distance varying of 

 course according to the condition of the sub- 

 ject ; the line approaches the margin of the 

 ramus or the spinous process, thence forward 

 or backward. In the anterior part of the stage 

 the vessel is enclosed in the triangular ligament 

 along its attachment to the bone; consequently, 

 it is separated from the surface by the superfi- 

 cial stratum of this structure first, in the second 

 place by the cms penis, covered by the ischio- 

 caveruous muscle, and behind it by the trans- 



versus perinei muscle ; and lastly, by the super- 

 ficial structures of the perineum. As the artery 

 proceeds it becomes more superficial, and finally 

 emerges from the triangular ligament, beneath 

 the subpubic ligament, as the dorsal artery of 

 the penis. 



It is in its third stage that the pudic artery 

 is exposed to danger in the lateral operation of 

 lithotomy ; it may be wounded in either of the 

 two steps of dividing the urethra and prostate 

 or the subsequent division of the superficial 

 structures: in the former case, the danger of 

 the accident will be greatest when the section is 

 effected with the scalpel or gorget, and in pro- 

 portion to the width of the blade, and the de- 

 gree to which the cutting edge may be directed 

 outward, will the danger be enhanced ; in the 

 second, the risk will be alike with all cutting 

 instruments, and will be determined by the 

 width of the blade, the attention paid to a pro- 

 per degree of lateralization, the manner in 

 which the instrument is made to effect a divi- 

 sion of the parts, and the extent of the section. 

 The branches of the pudic artery are numerous, 

 and may be conveniently arranged according to 

 the stage of its course, in which they are given 

 off. In its first, before its exit from the pelvis, 

 it gives branches to the bladder, the rectum, 

 the vesiculae, prostate, vagina, and uterus ; it 

 also frequently furnishes the middle hemor- 

 rhoidal. 



In its second stage, while external to the 

 pelvis, it gives branches to the glutens, the pyri- 

 formis, the obturator and gemelli muscles, the 

 sacro-sciatic ligament, the ischium, and sacrum ; 

 they anastomose with the ischiatic, the gluteal, 

 and internal circumflex arteries. 



Those which arise in its third stage are the 

 most important. 1. The artery gives, while on 

 the inside of the tuberosity of the ischium, 

 branches which are distinguished into external 

 and internal ; the former are small, and go to 

 the adipose structure beneath the tuberosity, to 

 the attachment of the biceps, to the obturator 

 internus, and the integuments : the internal are 

 larger ; they come through the obturator fascia, 

 run inward toward the anus, and are distributed 

 to the adipose cellular structure of the ischio- 

 rectal space, to the levator and sphincter ani, to 

 the extremity of the rectum, and the margin of 

 the anus; they anastomose with branches of 

 the middle hemorrhoidal artery and with those 

 of the other side : they are variable in number, 

 being one, two, or three, and are denominated 

 " external hemorrhoidal ;" they are liable to be 

 divided in operations in the vicinity of the 

 anus, e. g. in the superficial incision in the 

 lateral operation or in operation for fistula; 

 they are, however, so small that they seldom 

 give trouble, either ceasing to bleed spontane- 

 ously, or being commanded by brief compres- 

 sion. 



2. The perineal artery. At a short distance 

 from the base of the triangular ligament the 

 pudic gives off a branch of considerable size 

 and length, by many regarded as one of its 

 ultimate branches ; the pudic, according to 

 them, terminating by dividing into two branches, 

 an inferior, " the perineal," and a superior. 

 3 i 2 



