LXTERXA L ILIA C—ILIO- L UMBA R 567 



life it (Iocs not descend into the ju'lvis, Imt courses al)Ove the i)elvic hrim by the side 

 of the allantois, and later by the side of the l)ladder and urachiis, to the umbilicus, 

 under the name of the hypogastric artery. At the umbilicus it is joined by the 

 umbilical vein, and by the hypogastric artery of the oi)}iosite side. The two arteries, 

 now known as the umbilical, coil spirally round the vein on their way to the 

 placenta, forming the umbilical cord (tig. 3(58). After birth the hypogastric artery 

 ceases to be pervious beyond the superior vesical branch, and is converted into a 

 fibrous cord, the obliterated hypogastric artery. 



Variations. — (A) The internal iliac may be lunger or shorter than usual. It is seldom less 

 than an inch in length, but has been met with as short as half an inch, and as long as three 

 inches. The variation in length generally depends upon the length of the common iliac ; when 

 this bifurcates higher than usual, the internal iliac is then longer, and maj' lie at first above the 

 brim of the pelvis ; but the length may also depend ujKjn the artery itself dividing higher or 

 lower than usual into its branches. This division may occur anywhere between the brim of the 

 pelvis and the upper border of the sacro-sciatic foramen. (B) Its branches may be given off 

 without the arteiy dividing into an anterior and a posterior division, or one or more branches may 

 arise above the division. 



The branches of the posterior division of the internal iliac are: — (1) The 

 ilio-luml)ar; (2) the lateral sacral: and ('■-)) the gluteal. 



The branches of the anterior division are: — (l)The hypogastric; (2) the 

 sui)erior, middle, and inferior vesical: ( o j the middle hemorrhoidal; (4) the 

 uterine; (5) the vaginal; (6) the obturator; (7) the sciatic; and (8) the internal 

 pudic. 



Branches of the Posterior Division of the Internal Iliac Aetery 



1. THE ILIO-LUMBAR ARTERY 



The ilio-lumbar artery — a short vessel coming off from the posterior part of 

 the internal iliac artery — runs upwards and outAvards beneath the common iliac 

 artery, fir.st between the lumbo-sacral cord and obturator nerve, and then between 

 the psoas muscle and the vertebral column. On reaching the brim of the pelvis it 

 divides into two branches, an iliac and a lumbar. The iliac branch passes out- 

 wards beneath the psoas and anterior crural nen-e and, perforating the iliacus, 

 ramifies in the iliac fossa between that muscle and the bone. It supplies a nutrient 

 artery to the bone, and then breaks up into several branches which radiate from 

 the parent trunk, upwards towards the sacro-iliac synchondrosis, outwards towards 

 the crest of the ilium, downwards towards the anterior superior spine, and inwards 

 towards the pelvic cavity. The first anastomoses with the last lumbar; the second 

 with the external circumflex and gluteal; the third with the deep circumflex iliac 

 from the external iliac; the fourth with the iliac branch of the obturator. The 

 lumbar branch ascends beneath the psoas, and. sui>plying that muscle and the 

 (luailratus lumborum, anastomoses with the last lumbar artery. It sends a branch 

 into the spinal canal through the intervertebral foramen between the last lundiar 

 vertebra and the sacrum, which anastomoses with the other spinal arteries. The 

 ilio-lumbar artery is serially homologous with the lumbar arteries. Hence the 

 similaritv in its course and distriV)Ution. 



2. THE LATERAL SACRAL ARTEIHES 



The lateral sacral arteries, usually two in number, arise from the posterior 

 division of the internal iliac. The superior artery, when two are present, runs 

 downwards and inwards to the first anterior sacral foramen, through which it 

 passes; and, after supplying the spinal membranes and anastomosingwith the other 

 spinal arteries, passes through the first posterior sacral foramen, and is distributed 

 to the skin over the back of the sacrum, there anastomosing with branches of the 

 gluteal and sciatic arteries. The inferior lateral sacral descends on the side of 



