THE INTERNAL ILIAC ARTERY 675 



part of the rectum. It assists in forming the azygos arteries of the vagina, which 

 are anterior and posterior vessels, running longitudinally, and due to anastomoses 

 of the branches of the vaginal from each si_ie and the cervicovaginal artery. The 

 vaginal artery is frequently represented by two or three branches. 



Luschka, Hyrtl, \Yaldeyer, Robinson, and others, instead of describing the ovarian and 

 uterine arteries as two distinct vessels, regard them as constituting the chief parts of one vessel, 

 the arteria uterina ovarica. What has been called "the circle of Robinson" is composed of a 

 spiral segment (the arteria uterina ovarica), with a portion of the abdominal aorta, common 

 iliacs, and internal iliacs. 



Robinson 1 has made a careful study of this vascular circle; he shows that it is of great impor- 

 tance in certain surgical procedures, and that its remarkable "capacity for extension" saves it 

 from damage when the uterus is enormously distended by pregnancy, or when it is "drawn 

 through the pudendum with traction forceps for palpation, inspection, or repair." 



The author just quoted says further that the utero-ovarian artery has three origins, because 

 it develops from the Wolffian body: The ovarian segment arises from the abdominal aorta. 

 The uterine segment arises from the anterior branch of the internal iliac artery. The artery 

 of the round ligament arises from the deep epigastric. The arteria uterina ovarica secures 

 nutrition to the uterus by bringing blood from three sources. It is spiral throughout its entire 

 course, in certain parts is convoluted or looped, and it is accompanied by the pampiniform 

 plexus of veins. 



The three origins of this vessel are freely united by anastomoses, and rami laterales are given 

 off, which unite the bilateral vessels in the median line. Robinson describes three bifurcations 

 of the utero-ovarian artery. The distal bifurcation, which is "about midway between the uterus 

 and the pelvic wall," forms an acute angle with the main vessel. This bifurcation indicates 

 the point of division of the external from the internal genitals. The cervicovaginal artery 

 supplies the external genitals. The proximal bifurcation marks the situation of the ovary. 

 The artery bifurcates at an acute angle into two branches to supply the ovary and Fallopian 

 tube. The middle bifurcation consists of (1) the division of the uterine segment at the angle 

 formed by the uterus and oviduct ("forming the ramus oviductus and ramus ovarii"), and (2) 

 "the bifurcation of the ramus oviductus forming the ramus oviductus and the ramus ligamenti 

 teretis, or the segment of the round ligament." 2 



Applied Anatomy .As pointed out by Robinson, the source of bleeding after vaginal hys- 

 terectomy is usually the torn and undamped cervicovaginal artery. 



As previously pointed out, the spiral and convoluted course of the utero-ovarian artery allows 

 the uterus, ovary, and tube to be drawn into the vagina without injury to the vessels. Robinson 

 points out that in vaginal hysterectomy the genital circle is not divided and only the rami laterales 

 which go to the uterus are cut, the ovaries retaining a normal blood supply and continuing to 

 functionate. 



The obturator artery (a. obturatoria) (Fig. 473) passes forward and down- 

 ward on the lateral wall of the pelvis, to the upper part of the obturator foramen, 

 and, escaping from the pelvic cavity through a short canal, formed by a groove 

 on the under surface of the ascending ramus of the os pubis and the arched border 

 of the obturator membrane, it divides into an internal and external branch. In 

 the pelvic cavity this vessel is in relation, externally, with the obturator fascia; 

 internally, with the ureter, vas deferens, and peritoneum; while a little below it is 

 the obturator nerve. 



Branches. Within the pelvis, the obturator artery gives off an iliac branch (ramus 

 iliacus) to the iliac fossa, which supplies the bone and the Iliacus muscle, and 

 anastomoses with the iliolumbar artery; a vesical branch (ramus vesicalis), which 

 runs backward to supply the bladder; and a pubic branch (ramus pubicus), which 

 is given off from the vessel just before it leaves the pelvic cavity. The pubic 

 branch ascends upon the back of the pubis, communicating with offshoots from 

 the deep epigastric artery and with the corresponding vessel of the opposite side; 

 it is sometimes placed on the inner side of the femoral ring. 



Outside the pelvis, the obturator artery divides into an internal and an external 

 branch, which are deeply situated beneath the Obturator externus. 



1 F. Byron Robinson. The Utero-ovarian Artery, or the Genital Vascular Circle, 1903. 



2 Ibid. 



