570 THE BLOOD- VASCULAR SYSTEM. 



Surgical Anatomy. Any of these three vessels may require ligating for a wound or for 

 aneurism, which is generally traumatic. The glutenl artery is ligated by turning the patient 

 two-thirds over on his face and making an incision from the posterior superior spine of the ilium 

 to the upper and posterior angle of the great trochanter. This must expose the Gluteus maxi- 

 mus muscle, and its fibres are to be separated through the whole thickness of the muscle and 

 pulled apart with retractors. The contiguous margins of the Gluteus medius and Pyriformis 

 are now to be separated from each other, and the artery will be exposed emerging from the 

 sciatic notch. In ligation of the sciatic artery, the incision should be made parallel with that 

 for ligation of the gluteal, but one inch and a half lower down. After the fibres of the Gluteus 

 maximus have been separated, the vessel is to be sought for at the lower border of the Pyri- 

 formis ; the great sciatic nerve, which lies just above it, forming the chief guide to the artery. 



The External Iliac Artery (Fig. 312). 



The external iliac artery is larger in the adult than the internal iliac, and 

 passes obliquely downward and outward along the inner border of the Psoas 

 muscle, from the bifurcation of the common iliac to Poupart's ligament, Avhere it 

 enters the thigh and becomes the femoral artery. 



Relations. In front, with the peritoneum, subperitoneal areolar tissue, the ter- 

 mination of the ileum on the right side, and the sigmoid flexure on the left, and a thin 

 layer of fascia derived from the iliac fascia, which sui'rounds the artery and vein. 

 At its origin it is occasionally crossed by the ureter. The spermatic vessels descend 

 for some distance upon it near its termination, and it is crossed in this situation by 

 the genital branch of the genito-crural nerve and the deep circumflex iliac vein ; 

 the vas deferens curves down along its inner side. Behind, it is in relation with 

 the external iliac vein, which, at Poupart's ligament, lies at its inner side ; on the 

 left side the vein is altogether internal to the artery. Externally, it rests against 

 the Psoas muscle, from which it is separated by the iliac fascia. The artery rests 

 upon this muscle, near Poupart's ligament. Numerous lymphatic vessels and 

 glands are found lying on the front and inner side of the vessel. 



PLAN OF THE RELATIONS OF THE EXTERNAL ILIAC ARTERY. 



In front. 



Peritoneum, intestines, and fascia. 

 Near f Lymphatic vessels and glands. 



Poupart's J S P ermatic vessels. 

 L- ant I Genito-crural nerve (genital branch). 

 [ Deep circumflex iliac vein. 



Outer side. I \ Inner side. 



Psoas magnus. ( iliac. j External iliac vein and vas deferens 



Iliac fascia. \ j near Poupart's ligament. 



Behind. 



External iliac vein. 

 Psoas magnus. 



Surface Marking. The surface line indicating the course of the external iliac artery has 

 been already given (see page 560). 



Surgical Anatomy. The application of a ligature to the external iliac may be required in 

 cases of aneurism of the femoral artery or for a wound of the artery. This vessel may be 

 secured in any part of its course, excepting near its upper end, which is to be avoided on 

 account of the proximity of the great stream of blood in the internal iliac, and near its lower 

 end, which should also be avoided, on account of the proximity of the deep epigastric and cir- 

 cumflex iliac vessels. The patient having been placed in the supine position, an incision should 

 be made, commencing below at a point about three-quarters of an inch above Poupart's liga- 

 ment, and a little external to its middle, and running upward and outward, parallel to Poupart's 

 ligament, to a point one inch internal and one inch above the anterior superior spine of the 

 ilium. When the artery is deeply seated, more room will be required, and may be obtained by 

 curving the incision from the point last named inward toward the umbilicus for a short distance. 

 Another mode of ligating the vessel is the plan advocated by Sir Astley Cooper, by making 

 an incision close to Poupart's ligament from about half an inch outside of the external abdomi- 

 nal ring to one inch internal to the anterior superior spine of the ilium. This incision, being 



