ILIAC ARTERIES. 



833 



may be deficient or more developed, the obtu- 

 rator will be derived principally or altogether 

 from the internal iliac or from the epigastric ; 

 when both are equally so it will present the 

 double origin. 



2. The glutted artery, denominated also 

 posterior iliac, is the largest branch of the 

 internal iliac, and arises from, or is the conti- 

 nuation of the posterior division of that vessel ; 

 it runs downward, back ward, and outward, until 

 it reaches the superior part of the great sciatic 

 notch ; it then changes the direction of its 

 course, and making a turn passes directly out- 

 ward between the lumbo-sacral and the anterior 

 branch of the first sacral nerves, and escapes 

 from the pelvis through the upper part of the 

 notch above the pyriformis muscle, and accom- 

 panied by the superior gluteal nerve. As soon 

 as the artery has escaped from within the pelvis 

 and gained its external aspect, it divides into 

 branches. The trunk of this artery, as it is the 

 largest, so is it the shortest of the branches of 

 the iliac; within the pelvis it corresponds ex- 

 ternally to the lumbo-sacral nerve, internally to 

 the rectum, and inferiorly to the first sacral 

 nerve and the pyriformis ; it gives small 

 branches to the rectum, the pyriformis, and the 

 surrounding cellular structure ; at times it also 

 gives off the ilio-lumbar, the lateral sacral, or 

 the obturator. 



At its exit posteriorly from the pelvis it is 

 situate between the adjoining margins of the 

 pyriformis and the glutens minimus, and it is 

 covered by the gluteus maximus. 



The branches into which it divides after its 

 escape are two, a superficial and deep one. 

 The first passes outward and upward between 

 the glutei maximus and medms, and divides 

 into numerous branches, which are distributed 

 to these muscles, particularly to the maximus ; 

 many of them descend in its substance toward 

 its insertion, and there meet branches of the 

 circumflex (femoral) and sciatic arteries; others 

 pass through the muscle, become superficial, 

 and supply the integument and subcutaneous 

 fat; others again pass onward, traverse the 

 attachment of the gluteus maximus to the sa- 

 crum, and are distributed to the muscles and 

 integuments of the posterior sacral region. 



The second, the deep branch, passes outward, 

 upward, and forward, between the glutei medius 

 and minimus muscles toward the superior 

 anterior spinous process of the ilium in an 

 arched course around the attachment of the 

 gluteus minimus. As it proceeds it gives off 

 numerous branches upward from its convexity 

 and downward from its concavity ; the former 

 are distributed to the gluteus medius; the lat- 

 ter are chiefly two, of which one runs forward 

 and downward toward the anterior part of the 

 great trochanter between the two muscles, gives 

 branches to both, and finally throws itself into 

 the gluteus medius near the tyochanter, and is 

 consumed in it : it communicates freely with 

 the external circumflex artery. The other runs 

 downward and forward toward the back of the 

 trochanter, lies for some way upon the eluteus 

 minimus, or over the interval between ~it and 

 the pyriformis, gives branches to both muscles, 



VOL. ir. 



and then gains the surface of the os innomina- 

 tum by traversing the gluteus or by passing 

 between it and the pyriformis, pursues its course 

 upon the bone, to which it gives an artery, above 

 the ilio-femoral articulation, to the capsule of 

 which it also gives branches, and approaching 

 the anterior inferior spinous process of the ilium 

 it terminates in supplying the gluteus minimus, 

 and anastomosing with the external circumflex 

 artery. 



The deep division of the gluteal artery hav- 

 ing run round the line of attachment of the 

 gluteus minimus, and reached the superior 

 anterior spinous process, terminates in an anas- 

 tomosis with the circumflex iliac, the ilio-lumbar, 

 and the external circumflex arteries; branches 

 also turn over the crest of the ilium, and so 

 communicate with the iliolumbar. The deep 

 division, also, furnishes a nutritious artery to 

 the ilium, the canal for which is to be seen on 

 the dorsum of the bone. The branches of the 

 gluteal artery are numerous and large ; in order 

 to expose them the gluteus maximus having 

 been dissected clean may be detached from the 

 femur and raised toward the sacrum, when the 

 branches may be displayed running in every 

 direction as from an axis. 



The situation of the gluteal artery external to 

 the pelvis permits the trunk of the vessel to be 

 secured ; the gluteus maximus being the only 

 muscle by which it is covered, it may be exposed 

 by the division of that muscle; the situation of 

 the artery may be first determined " by drawing 

 a line from the posterior spinous process of the 

 ilium to the midspace between the tuberosity of 

 the ischiumand the great trochanter; if we divide 

 this line into three, we shall find the gluteal 

 artery emerging from the pelvis at the juncture 

 of its upper and middle thirds." * The ligature 

 of this artery in case of aneurism has been very 

 much superseded in favour of that of the inter- 

 nal or even of the primitive iliac, the latter of 

 which has been tied by Guthrie for aneurism 

 of the gluteal artery ; the propriety of this pro- 

 ceeding, however, may be questioned; the 

 ligature of either the internal or the primitive 

 iliac must be regarded a more serious operation 

 than that of the gluteal, and the latter has 

 proved so efficacious in the many instances in 

 which it has been had recourse to, that, while 

 it is practicable, the other can be hardly justi- 

 fiable. 



3. The ischiatic artery arises from the ante- 

 rior division of the internal iliac, which, after 

 having given off its internal branches, divides 

 into two, of which the posterior and larger is 

 the ischiatic; it is the second in size of the 

 branches of the iliac, being smaller than the 

 gluteal; but in the adult it appears, for the 

 most part, in direction the continuation of the 

 original vessel ; its course within the pelvis is 

 long; it descends, at the same time inclining 

 forward, and forming a curve convex backward, 

 toward the inferior part of the great sciatic 

 notch, and escapes through it from the pelvis 

 superior to the sacro-sciatic ligaments and infe- 

 rior to the pyriformis muscle; it then descends 



Harrison. 



3 I 



