VEIN. 



aortic arch, proceeding tranfverfely from left to right, and 

 joining the right fubclavian above the pericardium, as al- 

 ready defcribed. It receives in this coiirfe the left internal 

 mammary, the mediaftinal, thymic, fiiperior pericardiac, 

 and inferior thyroid veins. 



The internal mammary vein accompanies the artery. 

 The thymic veins are conneftcd with the mediaftinal, peri- 

 cardiac, &c. They end either in the fubclavian, internal 

 mammary, bronchia!, fuperior intercoftal, or thyroid. 



The i'uperior and pofterior pericardiac veins generally 

 end in the fubclavian ; but they may terminate in the bron- 

 chial or internal mammary. The vein accompanymg the 

 left phrenic nerve ends in the bronchial ; on the rigKl fide, 

 in the internal mammary. 



The vena azygos returns the blood from the parietes of 

 the cheft, except in fo far as the fuperior intercoftal veins 

 are concerned, which, as we have already defcribed, jom 

 the fubclavian. This vein connefts the fuperior and infe- 

 rior veins of the bodv : fw its inferior ramifications anaf- 

 tomofe with the lumbar or other abdominal veins. Hence, 

 where the inferior cava has been obftruAed, the blood has 

 found its way through the vena azygos into the fuperior. 



The minute origins of the vena azygos on the right fide 

 of the body are connefted with the vena cava, the lumbar, 

 or the renal veins. The trunk, at this part fmall, enters 

 the cheft, either with the aorta, or through an interval in 

 the right crus of the diaphragm. It afcends on the right 

 fide of the vertebral column, in front of the right intercoftal 

 arteries, covered by the pleura, with the trunk of the aorta 

 on its left, and the thoracic duft in the cellular fubftance 

 between it and that artery, receiving the intercoftal veins, 

 and increailng in fize. About the third dorfal vertebra it 

 quits the fpine, paffing forwards over the right bronchus 

 and pulmonary artery, receiving the right bronchial and 

 fome oefophageal veins, andaf a confiderable fize, and opens 

 into the back of the fuperior vena cava. 



The intercoftal veins, which it receives in its courfe, ac- 

 company the arteries of the fame name, and return the blood 

 from the intercoftal mufcles, andthofe of the back, from the 

 medulla fpinalis, from the vertebrjc, pleura, integuments, &c. 



About the feventh or eighth rib, the vena azygos receives 

 a large branch from the left fide, called hemi-azyga. This 

 begins by roots, which communicate with the abdominal 

 veins, from a trunk entering the cheft through the diaphragm, 

 afcending on the left fide of the cheft, receiving four, 

 five, o« more left inferior intercoftal veins, and then crofling 

 to the right fide, to join the trunk. Sometimes tlie hemi- 

 azyga joins the common trunk by two or three branches ; 

 fometimes it is not formed, and the left intercoftals proceed 

 ftraight to the right fide. See Wrift)erg, Obfervat. Anat. 

 de Vena azyga duplici, ahifque hujus veni varietatibus. 

 Goetting. 1778. 



III. The inferior Vena Cava. — The veins of the lower ex- 

 tremities, of the pelvis, and the abdomen, terminate in this 

 trunk. 



The veins of the lower, like thofe of the upper extremity, 

 confift of a deep-feated fet accompanying the arteries, and 

 therefore not requiring a feparate defcription ; and a fuper- 

 ficial order, covered only by the ikin, and intervening be- 

 tween it and the fafcia. The femoral vein is the common 

 channel for the blood of both thefe fyftems of veins. 



The fuperficial veins of the leg compofe two principal 

 trunks, called faphenae : there is indeed, as in the upper 

 limb, a plexus covering nearly the whole of the foot and leg, 

 of which the different branches every where communicate. 



The faphena externa or minor arifes from the venous 

 9 



plexus of the fole and back of the foot towards the outer 

 edge ; it runs below and behind the outer ankle, then rifes 

 over the calf, and having frequently communicated with the 

 deep-feated veins, terminates in the trunk of the popliteal. 



The faphena externa or major is made up by the veins 

 coming from the backs of the toes, and from the inner fide 

 of the fole, which form a confiderable trunk, afcendihg in 

 front of the internal malleolus, on the infide of the leg, 

 knee, and thigh, communicating frequently with the deep- 

 feated veins, and ending in the trunk of the femoral, about 

 an inch below the crural arch. Juft before its termination, 

 it receives fome veins from the external organs of generation 

 ( pudicae externa ) ; and a confiderable trunk, which de- 

 fcends from the integuments of the abdomen. 



The femoral vein pafTes under the crural arch, on the out- 

 fide of the correfponding artery, and continues in company 

 with- the artery, under the name of the external ihac, along 

 the fide of the pfoas magniis, until it meets with and joins 

 the internal iliac or hypogaftric vein from the pelvis, at the 

 facro-iliac fymphyfis, or the point where the common ihac ar- 

 tery bifurcates into its externa! and internal branches. Imme- 

 diately above the crural arch, the external iliac receives the 

 epigaftric and circumflex iliac veins. 



The internal iliac or hypogaftric vein is made up by tlie 

 union of venous trunks, correfponding to the various arteries 

 which are given oft" from the internal iliac artery. Thefe 

 veins accompany their refpeftive arteries ; but they are re- 

 markable for forming thick and intricate plexufes, which 

 furround the proftate, vcficulx feminales, neck, and fundus of 

 the bladder, urethra and vagina, and reftum. 



A large vein runs along the back of the penis, in its mid- 

 dle, between the two arterias dorfales,'and returns the blood 

 from the glans, corpus fpongiofum, bulb, and corpora ca- 

 vernofa. It paftes under the arch of the pubes, and divides 

 into a right and left branch, which run into the plexus 

 about the proftate and veficulse feminales. 



The fuperficial veins of the penis and fcrotum find their 

 way under the arch of the pubes, communicating with the 

 internal pudic veJTels, and end in the plexufes about the 

 neck of the bladder. 



They are united on the outfide with branches of the fper- 

 matic vein, and of the femoral. The puollate an'd veficula? 

 feminales, the lateral and inferior parts of the bladder, are 

 covered by numerous ramifications of a denfe plexus, from 

 which the trunks of the vefical veins convey tlie blood to the 

 hypogaftric. 



The veins in the labia are numerous, and communicate 

 frequently : thefe and the veins of the clitoris pafs under the 

 arch of the pubes ; the front of the vagina and urethra are 

 covered by a thick plexus, which is the common termination 

 of the external and internal pudic veflels. Thefe plexufes 

 envelope the fides of the vagina, the anterior, lateral, and 

 inferior parts of the bladder, and end in the vefical veins. 



The external hemorrhoidal veins end in the pudendal ; 

 the middle occupying a fpace of three or four inches, and 

 united with the plexufes already mentioned, join the hypo- 

 gaftric. Thefe latter then are interpofed between the in- 

 ternal hemorrhoidal, which joins the vena portarum,'and the 

 external, from which the hemorrhoidal flux proceeds. 



Large veins proceed from the vagina and uterus to the inter- 

 nal ihac : there are alfo the lateral facral veins, correfponding 

 in number to the facral foramina, out of which they proceed, 

 and united with the middle facral vein. The other veflels 

 contributing to the hypogaftric vein are, the obturatrix, 

 ifchiatic, pudenda communis, glutea, ileo lumbaris. 



The primary or common iliacs, fonned by the junftion, 



at 



