The poplital vein. — This vein is of large size, owing to the number and magnitude of the branches which it receives; it is joined by the tibial veins, by the external saphena, by the articular, and, lastly, by muscular veins of large size (sural) from the calf of the leg.
The poplitmal vein is placed posterior to its artery below, posterior and a little external to that vessel, at the upper part of the poplitzeal space. It is consequently situated between the artery and the posterior tibial nerve.
The valves in this vein are four or five in number. Its coats are stated by Crnveilhier and others to be of more than ordinary thick ness.
The femoral vein is the continuation of the poplitmal, which latter vessel, having passed through the tendinous opening in the adduc tor muscles, enters the thigh, and becomes femoral. In the lower third of the thigh the femoral vein and artery (enclosed in a com mon sheath) are contained in " Hunter's canal," the vein lying, as in the ham, posterior and external to the artery. In the centre of the thigh the vein is placed directly behind the artery ; but throughout its upper third the two vessels lie side by side, and in close con nection, the vein being the more internal. A thin, fibrous septem derived from the sheath which surrounds them passes backwards, and separates these vessels at this part of their course. The point of the aneurism needle is apt to be entangled by this partition, in con veying a ligature round the femoral artery, if care be not taken to keep the instrument on its outer or arterial side, whilst at the same time the sheath is kept tense. At the highest point of its course, just where it is about to pass beneath Poupart's ligament, the femoral vein constitutes the external boundary of the crural ring, and would therefore neces sarily bear the same relation to the neck of any hernial tumour which may have descended through this aperture. In its course through the thigh, the femoral vein is joined by nu merous muscular branches, also by the profunda vein, about an inch and a half below the crural arch, and, lastly, by the internal saphmta vein.
Its valves are from three to five in number.
Beneath Poupart's ligament the femoral becomes continuous with the external iliac vein.
The external iliac vein, whilst it accom panies the external iliac artery, and holds the same relation to surrounding parts as that vessel, is nevertheless differently related to its artery on the right and left side. As these vessels lie on the horizontal ramus of the pubis, their relative positions at both sides is the same, the vein being placed internal to the artery. On the left side this relation does not alter, and the vein lies on the inner side of the artery throughout its whole course ; on the right side, however, the vein, in its ascent, passes first behind the artery, and then appears slightly to its outer side.
The internal circumflex ilii and the two deep epigastric veins join the external iliac vein at the commencement of its course im mediately above Poupart's ligament. The farmer holds a remarkable relation to the ex ternal iliac artery, for it crosses that vessel at right angles to its anterior surface, and thus separates the artery from the fascia transver tabs.
-The internal iliac vein is formed in the cavity of the pelvis by the union of the veins which correspond to the numerous divisions of the internal iliac artery, —viz, by the glzifeeal, sciatic, internal pudic, and obiurator veins, all of which arise external to the pelvis ; and by numerous branches from the viscera contained within the pelvis, and which are remarkable for their plexiform arrangement. Of these, the vesical veins form a plexus which surrounds the neck of the bladder, and the prostate gland (vesico-prostatic plexus), receives the blood from the dorsal veins of the penis, and communicates freely with the inferior hamor rhoidal veins. In the female a similar plexus receives veins from the clitoris and the labia, and in addition there are two others, still more remarkable for their development, — the vaginal plexus, which surrounds the vagina near its commencement, and communicates with the vesical plexus in front, and with the haunorrhoidal veins behind, and the uterine plexus, the veins of which are scarcely ap parent except during gestation, and which communicate with the ovarian veins.