828 



ILIAC ARTERIES. 



aorta upon the left side of the spine ; Velpeau, 

 however, seems to question the existence of any 

 difference in the length of the two vessels, inas- 

 much as the right divides generally nearer to the 

 spine than the left, the inclination of their origin 

 to the left being thus compensated, but to what- 

 ever extent this view may hold good, it is by no 

 means strictly correct ; in fact the length of the 

 arteries, whether comparative or absolute, is far 

 from regular; nor is the preponderance, when 

 present, always upon the same side ; the opinion 

 generally entertained is probably correct, the 

 right artery being in the majority of instances 

 somewhat longer than the left ; but the writer 

 has found the left the longer of the two, and 

 the same disposition has been observed by J. F. 

 Meckel; this is, however, an unusual disposition. 

 The relations of the arteries are simple. 

 During their descent they are situate in front of 

 the bodies of the lumbar vertebrae, with the 

 intervening fibro-cartilages, of one, two, or more 

 of these bones, according to the height at which 

 the arteries arise, and also of the lateral part of 

 the base of the sacrum ; they are both covered 

 upon three sides by the peritoneum, viz. in 

 front and laterally, the membrane descending 

 upon them from the root of the mesentery; the 

 mesentery itself also and the small intestines 

 are placed before them, and the latter overlap 

 them upon either side. Farther, they are in 

 front of the superior branches of the middle 

 sacral artery and of the sympathetic nerve. 

 That of the right side at its outset is placed 

 before the left primitive iliac vein, which it 

 crosses at its junction with the cava, and par- 

 tially before the commencement of the cava 

 itself; during its course it is in front of the 

 right primitive vein, at first only partially, but, 

 as it proceeds, covering it to a greater extent, 

 until at its termination it is directly before it. 



External to both, but on a plane posterior to 

 them, are the psooe muscles, the left artery how- 

 ever being nearer to the muscle than the right, 

 between which and the psoas the right primitive 

 vein and the cava intervene, being at the same 

 time posterior to it. 



Internal to both at their origin is the middle 

 sacral artery ; on the left side the left primitive 

 vein lies along the inside of the artery, but on a 

 plane behind it. 



Anteriorly the arteries are crossed at their 

 termination by the corresponding ureter, that 

 duct being interposed between the peritoneum 

 and the vessel, but more adherent to the former. 

 The relation of the ureter to the iliac arteries is 

 not uniform, either on opposite sides or in 

 different subjects ; the bifurcation of the pri- 

 mitive iliac may be assumed as the mean point 

 of reference for its transit, the duct descending 

 into the pelvis between the external and internal 

 iliacs, and before the internal ; but its precise 

 relation will depend upon the height at which 

 the bifurcation takes place and the side of the 

 body to which it belongs, and hence it very 

 frequently, if not usually, crosses the external 

 iliac upon the right and the termination of the 

 internal on the left. 



The artery and vein, the relations of which 

 differ remarkably upon the two sides, the vein 



being external upon the right and internal upon 

 the left, and upon both posterior, are enclosed 

 within a condensed cellular investment, pro- 

 longed upward upon the aorta and downward 

 upon the secondary iliacs; upon the primitive 

 vessels it is so thin that it may at times seem 

 absent; but, as it descends, it increases in 

 thickness, and acquires upon the external iliacs 

 considerable strength. 



The primitive iliac arteries ordinarily give 

 only minute branches to the adjoining' parts, 

 viz. the ureter, the peritoneum, the vein, lym- 

 phatic glands and cellular structure ; but occa- 

 sionally they have been found to give off the 

 ilio-lumbar artery, and more rarely a renal or 

 spermatic artery.* 



Although, accord ing to the view usually taken, 

 the primitive iliac terminates by dividing into 

 internal and external, yet in many instances it 

 will be found that the primitive and external 

 iliacs appear as one vessel giving off the internal 

 from its posterior side, and nearly at right 

 angles, while in the foetus the reverse seems the 

 case, the primitive and internal being continuous 

 and rather giving off the external. 



INTERNAL ILIAC ARTERY.f (Arteria iliaca 

 internet, s. hypogastrica, s. umbilicalis; Fr. 

 artere iliaque interne, ou hypogastrique ; Germ. 

 Becken-pulsader oder innere Huft-pulsader.) 

 This artery from the time of birth' supplies the 

 viscera and parietes of the pelvis, both externally 

 and internally ; prior to that epoch it is the 

 channel through which the blood is trans- 

 mitted from the body of the fcetus to the 

 placenta, whence it may then be termed with 

 propriety the " placental artery," since such is 

 its chief office, the other distribution being of 

 inconsiderable extent, and the divisions of the 

 artery intended for it small in proportion; 

 hence the vessel presents a remarkable contrast 

 at the two periods of life, in the foetus being a 

 large and long vessel extending from the ter- 

 mination of the aorta, for, as has been before 

 stated, it seems at that time the continuation of 

 the primitive iliac artery, to the placenta giving 

 off in its course small branches to the viscera 

 and parietes of the pelvis, while in after life the 

 placental artery has disappeared, and in its 

 stead is found a short trunk of considerable 

 size, the commencement of the placental 

 artery as it had been from which arise nume- 

 rous vessels for the pelvis and its viscera. 



The internal iliac arises from the posterior 

 side of the primitive iliac artery,]; between the 

 body of the last lumbar vertebra or the sacro- 

 vertebral angle, and the sacro-iliac articulation, 

 but generally higher upon the right side than 

 the left ; it descends into the pelvis in front of 



* J. F. Meckel. 



f The internal iliac and its branches should be 

 examined first with the pelvis complete, the peri- 

 toneum and viscera being detached from its lateral 

 wall, and the latter alternately empty and distended j 

 afterward a section of the pelvis may be made 

 through the symphysis pubis and the middle of the 

 sacrum, preserving the viscera with their attach- 

 ments to one side , but this should not be done 

 until after the dissection of the perineum. 



\ See primitive iliac for point and mode of 

 division. 



