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Part IV. 242 ANA T O M Y. In general, the external or fuperficial veins of the fore- Sometimes a confiderable branch goes out from the arm are larger than the internal. lower extremity of the cava, near the bifurcation, chiefThe inferior Vena Cava havingrun down about a quar- ly on the right fide, which afterwards running up beter of an inch from the right auricle of the heart, with- tween the bodies and tranfverfe apophyfes of the vertebrae, in the pericardium, pierces that membrane and the ten- detaches the venae lumbares, and communicates with the dinous portion of the diaphragm. azygos. At this place it gives off the vence diaphragmaticce, or Sometimes a like branch comes from the beginning of phrenicae, which are diftributed to the diaphragm, and the left vena ilfiica, and, running up on that fide in the appear chiefly on its lower fide, one towards the right' fame manner, produces the lumbares. hand, and one towards the feft. The right vein is more The venae lumbares on one fide communicate by tranfbackward and lower than the left. The left is diftribu- verfe branches with thofe of the other fide, and likewife ted partly to the pericardium, and partly to the dia- with each other by branches more or lefs longitudinal. phragm ; and fometimes they fend rami to the capfuke The firft and fecond often go from the azygos, and renales. thereby they communicate with the intercoftal veins. The inferior cava hiving perforated the diaphragm, The lumbar veins fend fmall capillaries, in their paf’pafles through the pofterior part of the great fiffure of fage, to the fubftance of the bodies of the vertebras j the liver, penetrating a little into the fubftance of that and they are diftributed to the mufcles of the abdomen, vifetiS', between the great lobe and the lobulus Spigelii. quadratus lumborum, pfoas, iliacus, fee. They fend In its paffage, it fends off commonly three large branches, branches backward to the neighbouring vertebral mufcles, called vena hepatica, which are ramified in the liver. and to the canal of the fpine, and communicate with the Befides thefe large branches, it fends out feme other venal finufes. fmall ones, either before or immediately after it goes The inferior cava, having reached as low as the laft vertebra of the loins, and near the bifurcation of the out of the liver. In the fetus, as the vena cava paffes by the liver, aorta, runs in behind the right iliac artery, and there is it gives off theAuftus venofus, which communicates with divided into two fubaltern trunks, called the right And the fmus of the vena portae; and in adults is changed to left iliac veins. a flat ligament. From this bifurcation of the vena cava, the vena facra After its paffage, through the liver, the vena cava goes out, and accompanies the artery of the fame name turns from before backward, and from right to left, to- in its diftribution to the os facrum, to the nerves which lie ward the fpina dorfi, placing itfelf on the right fide of there, and to the membranes which cover both fides of the aorta, which it accompanies from thence downward. that bone. Having got as low as the arteriae renales, it gives off Each original iliac vein is divided on the fide of the os the veins of the fame name, termed formerly vena e- facrum, much after the fame manner as the arteries, into two large trunks. mulgentes. The right renal runs down a little obliquely, becaufe One of thefe trunks is named vena iliaca externa or of the fituation of the kidney. The left vein croffes on anterior ; the other interna or pofterior. veins follow nearly the courfe and diftribution the forefide of the trunk of the aorta, immediately-above of Thefe the iliac arteries, except that the hypogaftric vein does the fuperior mefenteric artery. They fend up the venae capfulares, which go to the not fend off the vena umbilicalis. glandulae renales, and downward; the venas adipofe, From the common trunk of the iliac veins, and fomewhich go to the fatty covering of the kidneys; and ordi- times from the origin of the iliaca externa, a particular narily the left renal vein furnilhes the left fpermatic vein. branch goes out, which is diftrib&ted to the mufculus pfoas, Afterwards they run to the finus, or cavity of the kid- iliacus, and quadratus lumborum ; and afterwards fends neys, in the fubftance of which they are diftributed by a ramus on the fore-fide of the laft tranfverfe apophyfis of the loins, to communicate with the laft lumbar vein. numerous ramifications. A little below the renal veins, the trunk of the cava The external iliac, a little before it leaves the abdofends out anteriorly, toward the right fide, the right ve- men, near the ligamentum Fallopii, lying on the pfoas na fpermatica. The left fpermatic vein comes common- and iliac mufcles, gives off almoft the feme branches with the artery of the fame name, and follows the fame ly from the left renalis. In their paffage, they fend fever al fmall branches on courfe. The chief branches are thefe: each fide, to the peritoneum and mefentery, where they A little before it goes out of the abdomen, it fends feem to be joined by anaftomofes with the vense mefa- off from the outfide, a fmall branch, which runs up along the crifta of the os ilium, and gives branches on raicae. The cava fends likewife off pofteriorly the venae lum- each fide to the lateral and pofterior lower portions of bares, which commonly arife in pairs. Thefe maybe the mufeuli abdominis, to the mufculus iliacus, fee. From the infide, before it leaves the abdomen, it fends divided into fuperior and inferior veins. Their origins vary in different manners. Sometimes off the vena epigaftrica; which having furnilhed feme rami to the neighbouring conglobated glands, runs the cava gives off a branch to each fide below the firft fmall up along the infide of the mufeuli refti, on which it is vertebra of the loins, which, like a common trunk, fur- ramified both ways. nifties the lumbar veins. This branch communicates with Afterwards the azygos.
