832 



ILIAC ARTERIES. 



the neck of the sac and rather to its inner side. 

 While within the canal the artery gives outward 

 a considerable branch its posterior or exter- 

 nal, or it might be with propriety called its 

 thyroid branch which runs downward and 

 backward along the external margin of the 

 thyroid foramen, between the two obturator 

 muscles, giving them branches, and at times 

 altogether consumed in them. Having reached 

 the tuberosity of the ischium, it gives branches 

 to the quadratus and adductor magnus muscles, 

 to the upper attachments of the flexors of the 

 leg, and to the ilio-femoral articulation, into 

 which it sometimes sends through the cotyloid 

 notch a branch more frequently supplied by 

 the internal circumflex (femoral) artery ; it also 

 sends another round the thyroid foramen, 

 which meets a similar branch from the obtura- 

 tor. It anastomoses with the internal circum- 

 flex and the sciatic arteries. At its entrance 

 into the thigh, the obturator artery is situate 

 above and before the obturator externus muscle, 

 and behind the pectinalis, which with some of 

 the fibres of the adductor longus must be divided 

 in order to expose the vessel. It descends be- 

 tween the pectinalis, the long and short adduc- 

 tors, and is distributed to them, the adductor 

 magnus, the gracilis, and the integuments upon 

 the upper and inner part of the thigh. It gives 

 also a branch, which runs round the margin 

 of the thyroid foramen, and meets the branch 

 already described from its thyroid branch. The 

 artery anastomoses freely with the internal cir- 

 cumflex artery. 



The obturator artery presents many varieties 

 as to its source, of which some are deserving 

 <of particular attention. According to J. F. 

 Meckel its ordinary source is the posterior 

 division of the internal iliac, either immediately 

 or by a trunk common to it and the ilio-lumbar, 

 but at least once in ten times it arises from another 

 source. The next most frequent is the internal 

 iliac itself above and before its division ; then 

 the anterior division of the iliac ; occasionally 

 the external iliac, and sometimes the femoral, 

 even so low as two inches from Poupart's liga- 

 ment. The most frequent variety, and which 

 according to the same authority is as common 

 as the origin from the internal iliac itself, is 

 that the artery arises from the epigastric, or from 

 a trunk common to both. Sometimes it has a 

 double origin, being formed by the union of 

 two branches of equal size, one from the epi- 

 gastric, and the other from the internal iliac, 

 and at times it has a different source upon op- 

 posite sides. In every case the destination of 

 the artery is the same; it runs to the inner 

 aperture of the subpubic canal, in order to 

 escape to the thigh, and in so doing it holds a 

 very intimate relation to the internal femoral 

 ring in those instances in which it proceeds 

 either from the epigastric or from the femoral. 

 When it arises from the epigastric, it runs 

 obliquely downward, backward, and inward, 

 above the crural arch, toward the superior 

 aperture of the pelvis, then entering the pelvis 

 posterior to the pubis it turns downward be- 

 neath it, and gains the subpubic foramen. 

 During its descent into the pelvis the artery 



superiorly is covered by the peritoneum, and 

 interiorly corresponds to Poupart's ligament 

 and the internal femoral ring, but the side of 

 the ring, at which it may be placed, varies in 

 different instances. When the common trunk 

 from which the epigastric and obturator arise is 

 short, the obturator lies close to the inside of 

 the external iliac vein and then is situate on 

 the outer side of the ring, while when the com- 

 mon trunk is long the artery is more remote 

 from the vein, coasts along the base of Gimber- 

 nat's ligament, and thus runs obliquely across 

 the front and inner side of the aperture. Ac- 

 cording to the case, therefore, will be the rela- 

 tion of the artery to the neck of femoral hernia ; 

 in the former it will be situate external and 

 posterior to it, in the latter anterior and inter- 

 nal. 



When hernia descends not only into the lym- 

 phatic compartment of the sheath, but, as has 

 been observed by Burns, also into that belong- 

 ing to the vein, thus forming a double protru- 

 sion, the artery may, if the common trunk be 

 short, be situate external to the neck of the 

 former and internal to that of the latter. 



The comparative frequency of this mode of 

 origin of the obturator artery has been diffe- 

 rently estimated. According to Monro it oc- 

 curs in one of twenty cases ; Velpeau coincides 

 in this opinion; Lawrence states it to be once in 

 ten ; J. F. Meckel considers it to be as frequent 

 as that from the internal iliac; and according 

 to the observations of Cloquet the proportion 

 of instances in 250 subjects in which the artery 

 was found to arise from the epigastric, whether 

 on one or both sides, was one in three, and that 

 of all the origins from the epigastric to all 

 those from other sources was still greater, about 

 1.2g. A more important question is the pro- 

 portion borne by those instances in which the 

 obturator arising from the epigastric is situate 

 on the inside of the neck of the hernia, to the 

 total number of such cases, or to that of cases 

 of femoral hernia requiring operation, for it is 

 obviously with it that the operator is concerned. 

 Cooper has not met the artery on the inside of 

 the hernia, though in six of twenty-one cases 

 he found the origin from the epigastric ; and 

 Lawrence states that the proportion of the for- 

 mer cases does not exceed one in eight or ten, 

 and therefore that the obturator artery would 

 be endangered only once in eighty or one hun- 

 dred operations. 



When the obturator arises from the femoral 

 artery, which Cloquet found in six of 250 

 subjects, it ascends into the abdomen beneath 

 the crural arch, along the pectinalis muscle and 

 internal to the femoral vein, and in femoral 

 hernia is found behind the sac. 



We are indebted to J. F. Meckei for solving 

 the apparent irregularity of these origins of the 

 obturator, and reducing them to a mere varia- 

 tion of the normal condition ; the obturator, as 

 has been stated, is normally connected with the 

 epigastric by an anastomotic branch, and hence 

 may be considered as having two origins, an 

 anterior and a posterior, a disposition the reality 

 of which is more manifest at the earlier periods 

 of life, and according as the one or the other 



