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ILIAC ARTERIES. 



designation adopted by Cliaussier, which, 

 while it recognises the identity of the vessel 

 throughout its course, sufficiently marks the 

 grounds of distinction between its two portions. 

 The external is somewhat smaller than the 

 primitive iliac, but in the adult considerably 

 larger than the internal ; its direction is down- 

 ward, outward, and forward, and hence it 

 forms with the primitive iliac a curve convex 

 backward, and seems the continuation of that 

 vessel; its length is from three to four inches, 

 and during its course it forms one or more 

 curvatures. 



Such is the disposition of the vessel in the 

 adult; but in the younger subject it is different 

 in some respects ; in the foetus the external iliac 

 is considerably smaller than the internal, and 

 does not seem the continuation of the primitive 

 iliac, which at that epoch is continued into the 

 internal; the external appearing rather as a 

 branch or a smaller division from a trunk 

 common to the other two : after birth the 

 relative disposition of the iliacs gradually 

 changes, until they acquire that of the adult. 



The relations of the external iliac artery are 

 as follows : posteriorly, it corresponds through 

 the upper half of its course to the lateral part 

 of the superior aperture of the pelvis; inclining 

 outwards as it descends, it corresponds in its 

 lower half to the os imiominatum, and the more 

 perfectly, the nearer it approaches the crural 

 arch, at which part it is placed in front of the 

 bone, crossing it nearly at right angles, and 

 separated from it by an interval occupied by 

 the psoo-i)iac aponeurosis and the psoas muscle. 



At its outset theexternal iliac vein is directly 

 behind the artery, and on its right side, also 

 the commencement of the primitive iliac vein, 

 the artery crossing the junction of the two 

 vessels, on that side, obliquely in its descent ; 

 during the remainder of its course, the vein, 

 though posterior to it, is also internal ; through- 

 out the lower half of its course it lies upon 

 the psoo-iliac aponeurosis, supported by the os 

 innominatum, and at first separated from the 

 bone only by the aponeurosis ; but as it pro- 

 ceeds separated from it also by the tendon of the 

 psoas parvus when present, and by the inner mar- 

 gin of the psoas magmis, it is very near to the os 

 innominatum, external to the ilio-pectineal emi- 

 nence, and being here supported by bone, and 

 made steady by its connections it may with 

 certainty be compressed and its circulation 

 perfectly commanded. Internally, the artery 

 corresponds above to the aperture of the pelvis, 

 to its viscera more or less intimately, according 

 to their state of distension or contraction, and 

 also to the small intestines which descend into 

 it; in the lower half of its course, the external 

 iliac vein, which at its outset is behind or 

 beneath the artery, is internal, though still some- 

 what posterior to it ;at the crural arch the artery 

 and vein are nearly upon the same level, being 

 supported by the os innominatum ; the artery 

 however somewhat anterior to the vein, but 

 as the vein recedes from the arch it inclines 

 less inward than the artery, and at the same 

 time retreats more from the surface ; and hence 



it gradually gets more completely behind the 

 artery until at its junction with the primitive 

 vein it is concealed by it anteriorly. 



The artery is covered by peritoneum, upon 

 its inner side through a considerable part of its 

 course ; above the membrane covers it com- 

 pletely ; but as it descends the extent becomes 

 less in consequence of the ascent of the vein ; 

 which thus gradually intervenes between the 

 artery and the membrane, and removes the 

 latter from it altogether in the lower part of its 

 course. When the primitive iliac divides at a 

 high point, the ureter descends into the pelvis 

 internal to the external iliac immediately after 

 its origin ; this occurs more frequently upon the 

 right side than the left. Beneath the perito- 

 neum the artery is covered by an investment, of 

 which presently again, attaching it superiorly 

 to the peritoneum and inferiorly to the vein. 



Externally the artery corresponds through its 

 entire course to the psoas magnus muscle, but 

 it is separated from it by the psoo-iliac fascia, to 

 which it is connected by its immediate invest- 

 ment ; the relation of the artery and the 

 muscle are, however, somewhat different at the 

 upper and lower parts of the vessel's course; 

 above, the artery does not lie upon the muscle, 

 but rests against its inner side along its anterior 

 part, while inferiorly it lies upon the inner 

 margin of the muscle at the same time that it 

 rests against it externally. 



The genito-crural nerve is situate along the 

 outer side of the artery ; this nerve, long and 

 slender.a branch of the lumbar plexus, descends 

 upon the psoas, extenal to the artery, and at 

 first at a little distance from it ; as it proceeds, it 

 approaches thevessel, and liesclose to itenveloped 

 in the fascia propria ; at thelower part of its course 

 its genital branch frequently passes in front 

 of the artery. The anterior crural vein is also 

 external to the artery ; but it is considerably 

 posterior to it, separated from it by the outer 

 margin of the psoas, between which and the 

 iliacus it lies, and also by the fascia iliaca, which 

 covers it ; the nerve is about half an inch from 

 the artery at the crural arch ; as it recedes from 

 the arch the distance increases. 



In front, the artery is covered immediately 

 by a cellular investment, formed by the sub- 

 peritorieal cellular structure the fascia propria 

 upon the posterior wall of the iliac fossa; 

 this encloses both the artery and the vein and at 

 the same time connects them ; it varies in its 

 condition according to the subject, in some it 

 appears a dense, but still cellular expansion, in 

 others from the deposition of fat it forms 

 an adipose stratum, which however still presents 

 a more condensed character in immediate con- 

 tact with the vessels ; it adheres closely to the 

 surface of the fascia iliaca upon either side of 

 the vessels and thus attaches them to it ; it is 

 prolonged upward upon the primitive iliac 

 vessels, and below, it ascends between the 

 peritoneum and the fascia transversalis upon 

 the anterior abdominal wall ; upon the primi- 

 tive iliac it is very thin and proportionally 

 weak ; but as it descends it increases in thick- 

 ness and strength until at the lower part of the 



