1. System of inferior vena cava. System of hepatic portal vein
2. Cava-caval and porto-caval anastomoses. Circulation of blood of foetus and new-born
3. Common, external and internal iliac arteries and veins
Lesson # 30
Theme 1. System of inferior vena cava. System of hepatic portal vein
Venae cavae are the two largest veins in the body. These blood vessels carry de-oxygenated blood from various regions of the body to the right atrium of the heart. As the de-oxygenated blood is returned to the heart and continues to flow through the cardiac cycle, it is transported to the lungs where it becomes oxygenated. The blood then travels back to the heart and is pumped out to the rest of the body via the aorta. Oxygen depleted blood is returned to the heart again via the venae cavae.
The superior vena cava is located in the upper chest region and is formed by the joining of the brachiocephalic veins. It is bordered by heart structures such as the aorta and pulmonary artery. The inferior vena cava is formed by the joining of the common iliac veins which meet a little below the small of the back. The inferior vena cava travels along the spine and transports blood from the lower extremities of the body to the posterior region of the right atrium.
Function of the Venae Cavae
· Superior Vena Cava: Brings de-oxygenated blood from the head, neck, arm and chest regions of the body to the right atrium.
· Inferior Vena Cava: Brings de-oxygenated blood from the lower body regions (legs, back, abdomen and pelvis) to the right atrium.
It is posterior to the abdominal cavity and runs alongside of the vertebral column on its right side (i.e. it is a retroperitoneal structure). It enters the right atrium at the lower right, back side of the heart.
The IVC is formed by the joining of the left and right common iliac veins and brings blood into the right atrium of the heart. It also anastomoses with the azygos vein system (which runs on the rght side of the vertebral column) and venous plexuses next to the spinal cord.
The tributaries of Inferior vena cava can be remembered using the mnemonic, "I Like To Rise So High", for Illiac vein (common), Lumbar vein, Testicular vein, Renal vein, Suprarenal vein and Hepatic vein.
Note that the vein that carries de-oxygenated blood from the upper half of the body is the superior vena cav
Inferior vena cava starts on level IV-V lumbar vertebrae by the confluence of left common iliac vein and right common iliac vein, to the right and beneath from bifurcation of aorta. It passes through special foramen in centrum tendineum of diaphragm into mediastinum and empties into right atrium.
There are parietal and visceral influxes of inferior vena cava.
The venæ cavæ and azygos veins, with their tributaries.
Parietal tributaries of inferior vena cava:
· lumbar veins are 3-4 pairs, which collect blood from areas according with ramification of lumbar arteries, they anastomose by right and left ascending lumbar veins;
· inferior phrenic veins collect blood from areas according with ramification same name arteries.
Follow veins are the visceral tributaries of inferior vena cava:
· in male - right testicular vein starts from posterior testicle margin. Testicular vein forms pampiniform plexus which enters to composition of spermatic cord. Left testicular vein (also left ovaricа vein in famile) empties by right angle into left renal vein;
· in famile - right ovaric
· vein begins from ovary hilus;
· renal veins, pair, pass from kidney hilus and, anastomosing with lumbar veins, emptiy into inferior vena cava between lumbar vertebrae first and second;
· right suprarenal vein, exits from hilus of adrenal gland. Left suprarenal vein falls into left renal vein;
· hepatic veins (3-4) veins fall into inferior vena cava in area of same name sulcus in liver.
The inferior vena cava (v. cava inferior) (577), returns to the heart the blood from the parts below the diaphragm. It
is formed by the junction of the two common iliac veins, on the right side of
the fifth lumbar vertebra. It ascends along the front of the vertebral column,
on the right side of the aorta, and, having reached the liver, is continued in
a groove on its posterior surface. It then perforates the diaphragm between the
median and right portions of its central tendon; it subsequently inclines
forward and medialward for about
Relations.—The abdominal portion of the inferior vena cava is in relation in front, from below upward, with the right common iliac artery, the mesentery, the right internal testicular artery, the inferior part of the duodenum, the pancreas, the common bile duct, the portal vein, and the posterior surface of the liver; the last partly overlaps and occasionally completely surrounds it; behind, with the vertebral column, the right Psoas major, the right crus of the diaphragm, the right inferior phrenic, suprarenal, renal and lumbar arteries, right sympathetic trunk and right celiac ganglion, and the medial part of the right suprarenal gland; on the right side, with the right kidney and ureter; on the left side, with the aorta, right crus of the diaphragm, and the caudate lobe of the liver.
The thoracic portion is only about
Peculiarities.—In Position.—This vessel is sometimes placed on the left side of the aorta, as high as the left renal vein, and, after receiving this vein, crosses over to its usual position on the right side; or it may be placed altogether on the left side of the aorta, and in such a case the abdominal and thoracic viscera, together with the great vessels, are all transposed.
Point of Termination.—Occasionally the inferior vena cava joins the azygos vein, which is then of large size. In such cases, the superior vena cava receives the whole of the blood from the body before transmitting it to the right atrium, except the blood from the hepatic veins, which passes directly into the right atrium.
Tributaries.—The inferior vena cava receives the following veins:
Right Spermatic or Ovarian.
The Lumbar Veins (vv. lumbales) four in number on each side, collect the blood by dorsal tributaries from the muscles and integument of the loins, and by abdominal tributaries from the walls of the abdomen, where they communicate with the epigastric veins. At the vertebral column, they receive veins from the vertebral plexuses, and then pass forward, around the sides of the bodies of the vertebræ, beneath the Psoas major, and end in the back part of the inferior cava. The left lumbar veins are longer than the right, and pass behind the aorta. The lumbar veins are connected together by a longitudinal vein which passes in front of the transverse processes of the lumbar vertebræ, and is called the ascending lumbar; it forms the most frequent origin of the corresponding azygos or hemiazygos vein, and serves to connect the common iliac, iliolumbar, and azygos or hemiazygos veins of its own side of the body.
The Testicular veins (vv. spermaticæ) (590) emerge from the back of the testis, and receive tributaries from the epididymis; they unite and form a convoluted plexus, called the pampiniform plexus, which constitutes the greater mass of the spermatic cord; the vessels composing this plexus are very numerous, and ascend along the cord, in front of the ductus deferens. Below the subcutaneous inguinal ring they unite to form three or four veins, which pass along the inguinal canal, and, entering the abdomen through the abdominal inguinal ring, coalesce to form two veins, which ascend on the Psoas major, behind the peritoneum, lying one on either side of the internal testicular artery. These unite to form a single vein, which opens on the right side into the inferior vena cava, at an acute angle; on the left side into the left renal vein, at a right angle. The testicular veins are provided with valves. 107 The left testicular vein passes behind the iliac colon, and is thus exposed to pressure from the contents of that part of the bowel.
The Ovarian Veins (vv. ovaricæ) correspond with the spermatic in the male; they form a plexus in the broad ligament near the ovary and uterine tube, and communicate with the uterine plexus. They end in the same way as the testicular veins in the male. Valves are occasionally found in these veins. Like the uterine veins, they become much enlarged during pregnancy.
The Renal Veins (vv. renales) are of large size, and placed in front of the renal arteries. The left is longer than the right, and passes in front of the aorta, just below the origin of the superior mesenteric artery. It receives the left testicular and left inferior phrenic veins, and, generally, the left suprarenal vein. It opens into the inferior vena cava at a slightly higher level than the right.
The Suprarenal Veins (vv. suprarenales) are two in number: the right ends in the inferior vena cava; the left, in the left renal or left inferior phrenic vein.
The Inferior Phrenic Veins (vv. phrenicæ inferiores) follow the course of the inferior phrenic arteris; the right ends in the inferior vena cava; the left is often represented by two branches, one of which ends in the left renal or suprarenal vein, while the other passes in front of the esophageal hiatus in the diaphragm and opens into the inferior vena cava.
The Hepatic Veins (vv. hepaticæ) commence in the substance of the liver, in the terminations of the portal vein and hepatic artery, and are arranged in two groups, upper and lower. The upper group usually consists of three large veins, which converge toward the posterior surface of the liver, and open into the inferior vena cava, while that vessel is situated in the groove on the back part of the liver. The veins of the lower group vary in number, and are of small size; they come from the right and caudate lobes. The hepatic veins run singly, and are in direct contact with the hepatic tissue. They are destitute of valves.
The hepatic portal vein is a blood vessel that conducts blood from the gastrointestinal tract and spleen to the liver. This blood is rich in nutrients that were extracted from food, and the liver processes these nutrients; it also filters toxins that may have been ingested with the food. The liver receives about 75% of its blood through the hepatic portal vein, with the remainder coming from the hepatic artery proper. The blood leaves the liver to the heart in the hepatic veins.
The hepatic portal vein is not a true vein, because it conducts blood to capillary beds in the liver and not directly to the heart. It is a major component of the hepatic portal system, one of only two portal venous systems in the body. The other is the hypophyseal portal system.
Conditions involving the hepatic portal vein cause considerable illness and death. An important example of such a condition is elevated blood pressure in the hepatic portal vein. This condition, called portal hypertension, is a major complication of cirrhosis.
In most individuals, the hepatic portal vein is formed by the union of the superior mesenteric vein and the splenic vein. For this reason, the hepatic portal vein is occasionally called the splenic-mesenteric confluence. Occasionally, the hepatic portal vein also directly communicates with the inferior mesenteric vein, although this is highly variable. Other tributaries of the hepatic portal vein include the cystic and gastric veins.
Immediately before reaching the liver, the portal vein divides into right and left. It ramifies further, forming smaller venous branches and ultimately portal venules. Each portal venule courses alongside a hepatic arteriole and the two vessels form the vascular components of the portal triad. These vessels ultimately empty into the hepatic sinusoids to supply blood to the liver.
The portal venous system has several anastomoses with the systemic venous system. In cases of portal hypertension these anastamoses may become engorged, dilated, or varicosed and subsequently rupture.
Accessory hepatic portal veins are those veins that drain directly into the liver without joining the hepatic portal vein. These include the paraumbilical veins as well as veins of the lesser omentum, falciform ligament, and those draining the gallbladder wall.
Vena portae hepatis is situated in thickness of hepatoduodenal ligament between ductus choledochus and proper hepatic artery (formula of their position DVA – from right to left). It originates behind head of pancreas by the confluence of superior, inferior mesenteric veinc and splenic vein. It collects venous blood from odd organs of abdominal cavity, except liver. Vena portae receives cystic vein, right and left gastric veins and prepyloric vein closely to liver hilus. Paraumbilical veins fall into portal vein in liver hilus.
There are cava-caval and porto-caval anastomoses between systems of portal vein, superior and inferior vanea cavae (see table on the next page).
The portal system (591) includes all the veins which drain the blood from the abdominal part of the digestive tube (with the exception of the lower part of the rectum) and from the spleen, pancreas, and gall-bladder. From these viscera the blood is conveyed to the liver by the portal vein. In the liver this vein ramifies like an artery and ends in capillary-like vessels termed sinusoids, from which the blood is conveyed to the inferior vena cava by the hepatic veins. From this it will be seen that the blood of the portal system passes through two sets of minute vessels, viz., (a) the capillaries of the digestive tube, spleen, pancreas, and gall-bladder; and (b) the sinusoids of the liver. In the adult the portal vein and its tributaries are destitute of valves; in the fetus and for a short time after birth valves can be demonstrated in the tributaries of the portal vein; as a rule they soon atrophy and disappear, but in some subjects they persist in a degenerate form.
The portal vein (vena portæ) is about
Tributaries.—The tributaries of the portal vein are:
The Lienal Vein (v. lienalis; splenic vein) commences by five or six large branches which return the blood from the spleen. These unite to form a single vessel, which passes from left to right, grooving the upper and back part of the pancreas, below the lineal artery, and ends behind the neck of the pancreas by uniting at a right angle with the superior mesenteric to form the portal vein. The lienal vein is of large size, but is not tortuous like the artery.
Tributaries.—The lineal vein receives the short gastric veins, the left gastroepiploic vein, the pancreatic veins, and the inferior mesenteric veins.
The short gastric veins (vv. gastricæ breves), four or five in number, drain the fundus and left part of the greater curvature of the stomach, and pass between the two layers of the gastrolienal ligament to end in the lienal vein or in one of its large tributaries.
The left gastroepiploic vein (v. gastroepiploica sinistra) receives branches from the antero-superior and postero-inferior surfaces of the stomach and from the greater omentum; it runs from right to left along the greater curvature of the stomach and ends in the commencement of the lienal vein.
The pancreatic veins (vv. pancreaticæ) consist of several small vessels which drain the body and tail of the pancreas, and open into the trunk of the lienal vein.
The inferior mesenteric vein (v. mesenterica inferior) returns blood from the rectum and the sigmoid, and descending parts of the colon. It begins in the rectum as the superior hemorrhoidal vein, which has its origin in the hemorrhoidal plexus, and through this plexus communicates with the middle and inferior hemorrhoidal veins. The superior hemorrhoidal vein leaves the lesser pelvis and crosses the left common iliac vessels with the superior hemorrhoidal artery, and is continued upward as the inferior mesenteric vein. This vein lies to the left of its artery, and ascends behind the peritoneum and in front of the left Psoas major; it then passes behind the body of the pancreas and opens into the lienal vein; sometimes it ends in the angle of union of the lienal and superior mesenteric veins.
Tributaries.—The inferior mesenteric vein receives the sigmoid veins from the sigmoid colon and iliac colon, and the left colic vein from the descending colon and left colic flexure.
The Superior Mesenteric Vein (v. mesenterica superior) returns the blood from the small intestine, from the cecum, and from the ascending and transverse portions of the colon. It begins in the right iliac fossa by the union of the veins which drain the terminal part of the ileum, the cecum, and vermiform process, and ascends between the two layers of the mesentery on the right side of the superior mesenteric artery. In its upward course it passes in front of the right ureter, the inferior vena cava, the inferior part of the duodenum, and the lower portion of the head of the pancreas. Behind the neck of the pancreas it unites with the lienal vein to form the portal vein.
Tributaries.—Besides the tributaries which correspond with the branches of the superior mesenteric artery, viz., the intestinal, ileocolic, right colic, and middle colic veins, the superior mesenteric vein is joined by the right gastroepiploic and pancreaticoduodenal veins.
The right gastroepiploic vein (v. gastroepiploica dextra) receives branches from the greater omentum and from the lower parts of the antero-superior and posteroinferior surfaces of the stomach; it runs from left to right along the greater curvature of the stomach between the two layers of the greater omentum.
The pancreaticoduodenal veins (vv. pancreaticoduodenales) accompany their corresponding arteries; the lower of the two frequently joins the right gastroepiploic vein.
The Coronary Vein (v. coronaria ventriculi; gastric vein) derives tributaries from both surfaces of the stomach; it runs from right to left along the lesser curvature of the stomach, between the two layers of the lesser omentum, to the esophageal opening of the stomach, where it receives some esophageal veins. It then turns backward and passes from left to right behind the omental bursa and ends in the portal vein.
The Pyloric Vein is of small size, and runs from left to right along the pyloric portion of the lesser curvature of the stomach, between the two layers of the lesser omentum, to end in the portal vein.
The Cystic Vein (v. cystica) drains the blood from the gall-bladder, and, accompanying the cystic duct, usually ends in the right branch of the portal vein.
Parumbilical Veins (vv. parumbilicales).—In the course of the ligamentum teres of the liver and of the middle umbilical ligament, small veins (parumbilical) are found which establish an anastomosis between the veins of the anterior abdominal wall and the portal, hypogastric, and iliac veins. The best marked of these small veins is one which commences at the umbilicus and runs backward and upward in, or on the surface of, the ligamentum teres between the layers of the falciform ligament to end in the left portal vein.
Collateral venous circulation to relieve portal obstruction in the liver may be effected by communications between (a) the gastric veins and the esophageal veins which often project as a varicose bunch into the stomach, emptying themselves into the hemiazygos vein; (b) the veins of the colon and duodenum and the left renal vein; (c) the accessory portal system of Sappey, branches of which pass in the round and falciform ligaments (particularly the latter) to unite with the epigastric and internal mammary veins, and through the diaphragmatic veins with the azygos; a single large vein, shown to be a parumbilical vein, may pass from the hilus of the liver by the round ligament to the umbilicus, producing there a bunch of prominent varicose veins known as the caput medusæ; (d) the veins of Retzius, which connect the intestinal veins with the inferior vena cava and its retroperitoneal branches; (e) the inferior mesenteric veins, and the hemorrhoidal veins that open into the hypogastrics; (f) very rarely the ductus venosus remains patent, affording a direct connection between the portal vein and the inferior vena cava.
Theme 2. Cava-caval and porto-caval anastomoses. Circulation of blood of foetus and new-born
Position of anastomose
V. cava superior
v. cava inferior
v. epigastrica superior (tributary of the internal thoracic vein) and v. Thoracoepigastrica (tributary of the subclavian vein)
v. epigastrica inferior (tributary of the external iliac vein) and v. Epigastrica superficialis (tributary of the femoral vein)
In anterior abdominal wall round the navel
V. cava superior
And v. Cava inferior
vv. azygos and hemiazygos
On posterior abdominal wall
V. cava superior
And v. Cava inferior
Rr. spinales (tributary of the vv. Intercostales posteriores)
Rr. spinales (tributary of the vv. Lumbales)
Form internal and external vertebral plexus
V. cava superior and v. Portae
v. epigastrica superior (tributary of the internal thoracic vein)
In anterior abdominal wall round the navel
V. cava superior and v. Portae
Vv. esophageales (tributary of the azygos vein)
v. gastrica sinistra
Near gastric cardia
V. cava inferior and v. Portae
v. epigastrica inferior (tributary of the external iliac vein)
In anterior abdominal wall
V. cava inferior and v. Portae
V. rectalis media (tributary of the internal iliac vein)
V. rectalis superior (tributary of the inferior mesenteric vein)
Plexus venosus rectalis
V. cava inferior and v. Portae
Vv. mesenterica superior and inferior
In thickness of ascending and descending colon
Circulatory system of the foetus has a row of peculiarities that differ from adult one:
- arterial blood reaches the foetus through umbilical vein from placenta;
- exclusive of umbilical vein, a blood in vessels is mixed;
- venous (Аranti) duct functions between umbilical and inferior vena cava by veins;
- blood from inferior vena cava gets from right atrium through the ovale foramen into left atrium;
- pulmonary circulation does not function;
- arterial (Botalova) duct functions between aortic arch and pulmonary trunk, through the which blood from pulmonary blood circle passes in systemic circulation;
- more oxygenated blood supplies head, neck, upper limbs and superior part of torso. Inferior part of trunk and lower limbs supplied by mixed blood, which is insufficiently saturated by oxygen, that's why these body portions of foetus fall behind in development in compare of head and upper part of torso.
After birth breath starts and pulmonary circulation begins to function. Umbilical vessels overgrow in 6-7 days, Botali duct - in 9-10 days and oval foramen in interatrial wall – in 30 days after birth
Peculiarities in the Vascular System in the Fetus The chief peculiarities of the fetal heart are the direct communication between the atria through the foramen ovale, and the large size of the valve of the inferior vena cava. Among other peculiarities the following may be noted. (1) In early fetal life the heart lies immediately below the mandibular arch and is relatively large in size. As development proceeds it is gradually drawn within the thorax, but at first it lies in the middle line; toward the end of pregnancy it gradually becomes oblique in direction. (2) For a time the atrial portion exceeds the ventricular in size, and the walls of the ventricles are of equal thickness: toward the end of fetal life the ventricular portion becomes the larger and the wall of the left ventricle exceeds that of the right in thickness. (3) Its size is large as compared with that of the rest of the body, the proportion at the second month being 1 to 50, and at birth, 1 to 120, while in the adult the average is about 1 to 160.
The foramen ovale, situated at the lower part of the atrial septum, forms a free communication between the atria until the end of fetal life. A septum (septum secundum) grows down from the upper wall of the atrium to the right of the primary septum in which the foramen ovale is situated; shortly after birth it fuses with the primary septum and the foramen ovale is obliterated.
The valve of the inferior vena cava serves to direct the blood from that vessel through the foramen ovale into the left atrium.
The peculiarities in the arterial system of the fetus are the communication between the pulmonary artery and the aorta by means of the ductus arteriosus, and the continuation of the hypogastric arteries as the umbilical arteries to the placenta.
The ductus arteriosus is a short tube, about
The hypogastric arteries run along the sides of the bladder and thence upward on the back of the anterior abdominal wall to the umbilicus; here they pass out of the abdomen and are continued as the umbilical arteries in the umbilical cord to the placenta. They convey the fetal blood to the placenta.
The peculiarities in the venous system of the fetus are the communications established between the placenta and the liver and portal vein, through the umbilical vein; and between the umbilical vein and the inferior vena cava through the ductus venosus.
Fetal Circulation (502).
—The fetal blood is returned from the placenta to the fetus by the umbilical vein. This vein enters the abdomen at the umbilicus, and passes upward along the free margin of the falciform ligament of the liver to the under surface of that organ, where it gives off two or three branches, one of large size to the left lobe, and others to the lobus quadratus and lobus caudatus. At the porta hepatis (transverse fissure of the liver) it divides into two branches: of these, the larger is joined by the portal vein, and enters the right lobe; the smaller is continued upward, under the name of the ductus venosus, and joins the inferior vena cava. The blood, therefore, which traverses the umbilical vein, passes to the inferior vena cava in three different ways. A considerable quantity circulates through the liver with the portal venous blood, before entering the inferior vena cava by the hepatic veins; some enters the liver directly, and is carried to the inferior cava by the hepatic veins; the remainder passes directly into the inferior vena cava through the ductus venosus.
In the inferior vena cava, the blood carried by the ductus venosus and hepatic veins becomes mixed with that returning from the lower extremities and abdominal wall. It enters the right atrium, and, guided by the valve of the inferior vena cava, passes through the formen ovale into the left atrium, where it mixes with a small quantity of blood returned from the lungs by the pulmonary veins. From the left atrium it passes into the left ventricle; and from the left ventricle into the aorta, by means of which it is distributed almost entirely to the head and upper extremities, a small quantity being probably carried into the descending aorta. From the head and upper extremities the blood is returned by the superior vena cava to the right atrium, where it mixes with a small portion of the blood from the inferior vena cava. From the right atrium it descends into the right ventricle, and thence passes into the pulmonary artery. The lungs of the fetus being inactive, only a small quantity of the blood of the pulmonary artery is distributed to them by the right and left pulmonary arteries, and returned by the pulmonary veins to the left atrium: the greater part passes through the ductus arteriosus into the aorta, where it mixes with a small quantity of the blood transmitted by the left ventricle into the aorta. Through this vessel it descends, and is in part distributed to the lower extremities and the viscera of the abdomen and pelvis, but the greater amount is conveyed by the umbilical arteries to the placenta.
From the preceding account of the circulation of the blood in the fetus the following facts will be evident: (1) The placenta serves the purposes of nutrition and excretion, receiving the impure blood from the fetus, and returning it purified and charged with additional nutritive material. (2) Nearly the whole of the blood of the umbilical vein traverses the liver before entering the inferior vena cava; hence the large size of the liver, especially at an early period of fetal life. (3) The right atrium is the point of meeting of a double current, the blood in the inferior vena cava being guided by the valve of this vessel into the left atrium, while that in the superior vena cava descends into the right ventricle. At an early period of fetal life it is highly probable that the two streams are quite distinct; for the inferior vena cava opens almost directly into the left atrium, and the valve of the inferior vena cava would exclude the current from the right ventricle. At a later period, as the separation between the two atria becomes more distinct, it seems probable that some mixture of the two streams must take place. (4) The pure blood carried from the placenta to the fetus by the umbilical vein, mixed with the blood from the portal vein and inferior vena cava, passes almost directly to the arch of the aorta, and is distributed by the branches of that vessel to the head and upper extremities. (5) The blood contained in the descending aorta, chiefly derived from that which has already circulated through the head and limbs, together with a small quantity from the left ventricle, is distributed to the abdomen and lower extremities.
Changes in the Vascular System at Birth.—At birth, when respiration is established, an increased amount of blood from the pulmonary artery passes through the lungs, and the placental circulation is cut off. The foramen ovale is closed by about the tenth day after birth: the valvular fold above mentioned adheres to the margin of the foramen for the greater part of its circumference, but a slit-like opening is left between the two atria above, and this sometimes persists.
The ductus arteriosus begins to contract immediately after respiration is established, and is completely closed from the fourth to the tenth day; it ultimately degenerates into an impervious cord, the ligamentum arteriosum, which connects the left pulmonary artery to the arch of the aorta.
Of the hypogastric arteries, the parts extending from the sides of the bladder to the umbilicus become obliterated between the second and fifth days after birth, and project as fibrous cords, the lateral umbilical ligaments, toward the abdominal cavity, carrying on them folds of peritoneum.
The umbilical vein and ductus venosus are completely obliterated between the second and fifth days after birth; the former becomes the ligamentum teres, the latter the ligamentum venosum, of the liver.
The abdominal aorta divides, on the left side of the body of the fourth lumbar vertebra, into the two common iliac arteries (531, 539). Each is about 5 cm. in length. They diverge from the termination of the aorta, pass downward and lateralward, and divide, opposite the intervertebral fibrocartilage between the last lumbar vertebra and the sacrum, into two branches, the external iliac and hypogastric arteries; the former supplies the lower extremity; the latter, the viscera and parietes of the pelvis.
The right common iliac artery (539) is somewhat longer than the left, and passes more obliquely across the body of the last lumbar vertebra. In front of it are the peritoneum, the small intestines, branches of the sympathetic nerves, and, at its point of division, the ureter. Behind, it is separated from the bodies of the fourth and fifth lumbar vertebræ, and the intervening fibrocartilage, by the terminations of the two common iliac veins and the commencement of the inferior vena cava. Laterally, it is in relation, above, with the inferior vena cava and the right common iliac vein; and, below, with the Psoas major. Medial to it, above, is the left common iliac vein.
The left common iliac artery is in relation, in front, with the peritoneum, the small intestines, branches of the sympathetic nerves, and the superior hemorrhoidal artery; and is crossed at its point of bifurcation by the ureter. It rests on the bodies of the fourth and fifth lumbar vertebræ, and the intervening fibrocartilage. The left common iliac vein lies partly medial to, and partly behind the artery; laterally, the artery is in relation with the Psoas major.
Branches.—The common iliac arteries give off small branches to the peritoneum, Psoas major, ureters, and the surrounding areolar tissue, and occasionally give origin to the iliolumbar, or accessory renal arteries.
Peculiarities.—The point of origin varies according to the bifurcation of the aorta. In three-fourths of a large number of cases, the aorta bifurcated either upon the fourth lumbar vertebra, or upon the fibrocartilage between it and the fifth; the bifurcation being, in one case out of nine, below, and in one out of eleven, above this point. In about 80 per cent. of the cases the aorta bifurcated within 1.25 cm. above or below the level of the crest of the ilium; more frequently below than above.
The point of division is subject to great variety. In two-thirds of a large number of cases it was between the last lumbar vertebra and the upper border of the sacrum; being above that point in one case out of eight, and below it in one case out of six. The left common iliac artery divides lower down more frequently than the right.
The relative lengths, also, of the two common iliac arteries vary. The right common iliac was the longer in sixty-three cases; the left in fifty-two; while they were equal in fifty-three. The length of the arteries varied, in five-sevenths of the cases examined, from 3.5 to 7.5 cm.; in about half of the remaining cases the artery was longer, and in the other half, shorter; the minimum length being less than 1.25 cm., the maximum, 11 cm. In rare instances, the right common iliac has been found wanting, the external iliac and hypogastric arising directly from the aorta.
Collateral Circulation.—The principal agents in carrying on the collateral circulation after the application of a ligature to the common iliac are: the anastomoses of the hemorrhoidal branches of the hypogastric with the superior hemorrhoidal from the inferior mesenteric; of the uterine, ovarian, and vesical arteries of the opposite sides; of the lateral sacral with the middle sacral artery; of the inferior epigastric with the internal mammary, inferior intercostal, and lumbar arteries; of the deep iliac circumflex with the lumbar arteries; of the iliolumbar with the last lumbar artery; of the obturator artery, by means of its pubic branch, with the vessel of the opposite side and with the inferior epigastric.
Internal Iliac Artery supplies the walls and viscera of the pelvis, the buttock, the generative organs, and the medial side of the thigh. It is a short, thick vessel, smaller than the external iliac, and about 4 cm. in length. It arises at the bifurcation of the common iliac, opposite the lumbosacral articulation, and, passing downward to the upper margin of the greater sciatic foramen, divides into two large trunks, an anterior and a posterior.
Relations.—It is in relation in front with the ureter; behind, with the internal iliac vein, the lumbosacral trunk, and the Piriformis muscle; laterally, near its origin, with the external iliac vein, which lies between it and the Psoas major muscle; lower down, with the obturator nerve.
In the fetus, the hypogastric artery is twice as large as the external iliac, and is the direct continuation of the common iliac. It ascends along the side of the bladder, and runs upward on the back of the anterior wall of the abdomen to the umbilicus, converging toward its fellow of the opposite side. Having passed through the umbilical opening, the two arteries, now termed umbilical, enter the umbilical cord, where they are coiled around the umbilical vein, and ultimately ramify in the placenta.
At birth, when the placental circulation ceases, the pelvic portion only of the artery remains patent and constitutes the hypogastric and the first part of the superior vesical artery of the adult; the remainder of the vessel is converted into a solid fibrous cord, the lateral umbilical ligament (obliterated hypogastric artery) which extends from the pelvis to the umbilicus.
Peculiarities as Regards Length.—In two-thirds of a large number of cases, the length of the hypogastric varied between 2.25 and 3.4 cm.; in the remaining third it was more frequently longer than shorter, the maximum length being about 7 cm. the minimum about 1 cm.
Collateral Circulation.—The circulation after ligature of the hypogastric artery is carried on by the anastomoses of the uterine and ovarian arteries; of the vesical arteries of the two sides; of the hemorrhoidal branches of the hypogastric with those from the inferior mesenteric; of the obturator artery, by means of its pubic branch, with the vessel of the opposite side, and with the inferior epigastric and medial femoral circumflex; of the circumflex and perforating branches of the profunda femoris with the inferior gluteal; of the superior gluteal with the posterior branches of the lateral sacral arteries; of the iliolumbar with the last lumbar; of the lateral sacral with the middle sacral; and of the iliac circumflex with the iliolumbar and superior gluteal. 104
The superior vesical artery (a. vesicalis superior) supplies numerous branches to the upper part of the bladder. From one of these a slender vessel, the artery to the ductus deferens, takes origin and accompanies the duct in its course to the testis, where it anastomoses with the internal testicular artery. Other branches supply the ureter. The first part of the superior vesical artery represents the terminal section of the pervious portion of the fetal hypogastric artery.
The inferior vesical artery (a. vesicalis inferior) frequently arises in common with the middle hemorrhoidal, and is distributed to the fundus of the bladder, the prostate, and the vesiculæ seminales. The branches to the prostate communicate with the corresponding vessels of the opposite side.
The middle hemorrhoidal artery (a. hæmorrhoidalis media) usually arises with the preceding vessel. It is distributed to the rectum, anastomosing with the inferior vesical and with the superior and inferior hemorrhoidal arteries. It gives offsets to the vesiculæ seminales and prostate.
The uterine artery (a. uterina) (540) springs from the anterior division of the hypogastric and runs medialward on the Levator ani and toward the cervix uteri; about 2 cm. from the cervix it crosses above and in front of the ureter, to which it supplies a small branch. Reaching the side of the uterus it ascends in a tortuous manner between the two layers of the broad ligament to the junction of the uterine tube and uterus. It then runs lateralward toward the hilus of the ovary, and ends by joining with the ovarian artery. It supplies branches to the cervix uteri and others which descend on the vagina; the latter anastomose with branches of the vaginal arteries and form with them two median longitudinal vessels—the azygos arteries of the vagina—one of which runs down in front of and the other behind the vagina. It supplies numerous branches to the body of the uterus, and from its terminal portion twigs are distributed to the uterine tube and the round ligament of the uterus.
The vaginal artery (a. vaginalis) usually corresponds to the inferior vesical in the male; it descends upon the vagina, supplying its mucous membrane, and sends branches to the bulb of the vestibule, the fundus of the bladder, and the contiguous part of the rectum. It assists in forming the azygos arteries of the vagina, and is frequently
The obturator artery (a. obturatoria) passes forward and downward on the lateral wall of the pelvis, to the upper part of the obturator foramen, and, escaping from the pelvic cavity through the obturator canal, it divides into an anterior and a posterior branch. In the pelvic cavity this vessel is in relation, laterally, with the obturator fascia; medially, with the ureter, ductus deferens, and peritoneum; while a little below it is the obturator nerve.
Branches.—Inside the pelvis the obturator artery gives off iliac branches to the iliac fossa, which supply the bone and the Iliacus, and anastomose with the ilio-lumbar artery; a vesical branch, which runs backward to supply the bladder; and a public branch, which is given off from the vessel just before it leaves the pelvic cavity. The pubic branch ascends upon the back of the pubis, communicating with the corresponding vessel of the opposite side, and with the inferior epigastric artery.
Outside the pelvis, the obturator artery divides at the upper margin of the obturator foramen, into an anterior and a posterior branch which encircle the foramen under cover of the Obturator externus.
The anterior branch runs forward on the outer surface of the obturator membrane and then curves downward along the anterior margin of the foramen. It distributes branches to the Obturator externus, Pectineus, Adductores, and Gracilis, and anastomoses with the posterior branch and with the medial femoral circumflex artery.
The posterior branch follows the posterior margin of the foramen and turns forward on the inferior ramus of the ischium, where it anastomoses with the anterior branch. It gives twigs to the muscles attached to the ischial tuberosity and anastomoses with the inferior gluteal. It also supplies an articular branch which enters the hip-joint through the acetabular notch, ramifies in the fat at the bottom of the acetabulum and sends a twig along the ligamentum teres to the head of the femur.
Peculiarities.—The obturator artery sometimes arises from the main stem or from the posterior trunk of the hypogastric, or it may spring from the superior gluteal artery; occasionally it arises from the external iliac. In about two out of every seven cases it springs from the inferior epigastric and descends almost vertically to the upper part of the obturator foramen. The artery in this course usually lies in contact with the external iliac vein, and on the lateral side of the femoral ring (541 A); in such cases it would not be endangered in the operation for strangulated femoral hernia. Occasionally, however, it curves along the free margin of the lacunar ligament (541 B), and if in such circumstances a femoral hernia occurred, the vessel would almost completely encircle the neck of the hernial sac, and would be in great danger of being wounded if an operation were performed for strangulation.
The internal pudendal artery (a. pudenda interna; internal pudic artery) is the smaller of the two terminal branches of the anterior trunk of the hypogastric, and supplies the external organs of generation. Though the course of the artery is the same in the two sexes, the vessel is smaller in the female than in the male, and the distribution of its branches somewhat different. The description of its arrangement in the male will first be given, and subsequently the differences which it presents in the female will be mentioned.
The internal pudendal artery in the male passes downward and outward to the lower border of the greater sciatic foramen, and emerges from the pelvis between the Piriformis and Coccygeus; it then crosses the ischial spine, and enters the perineum through the lesser sciatic foramen. The artery now crosses the Obturator internus, along the lateral wall of the ischiorectal fossa, being situated about 4 cm. above the lower margin of the ischial tuberosity. It gradually approaches the margin of the inferior ramus of the ischium and passes forward between the two layers of the fascia of the urogenital diaphragm; it then runs forward along the medial margin of the inferior ramus of the pubis, and about 1.25 cm. behind the pubic arcuate ligament it pierces the inferior fascia of the urogenital diaphragm and divides into the dorsal and deep arteries of the penis.
Relations.—Within the pelvis, it lies in front of the Piriformis muscle, the sacral plexus of nerves, and the inferior gluteal artery. As it crosses the ischial spine, it is covered by the Glutæus maximus and overlapped by the sacrotuberous ligament. Here the pudendal nerve lies to the medial side and the nerve to the Obturator internus to the lateral side of the vessel. In the perineum it lies on the lateral wall of the ischiorectal fossa, in a canal (Alcock’s canal) formed by the splitting of the obturator fascia. It is accompanied by a pair of venæ comitantes and the pudendal nerve.
Peculiarities.—The internal pudendal artery is sometimes smaller than usual, or fails to give off one or two of its usual branches; in such cases the deficiency is supplied by branches derived from an additional vessel, the accessory pudendal, which generally arises from the internal pudendal artery before its exit from the greater sciatic foramen. It passes forward along the lower part of the bladder and across the side of the prostate to the root of the penis, where it perforates the urogenital diaphragm, and gives off the branches usually derived from the internal pudendal artery. The deficiency most frequently met with is that in which the internal pudendal ends as the artery of the urethral bulb, the dorsal and deep arteries of the penis being derived from the accessory pudendal. The internal pudendal artery may also end as the perineal, the artery of the urethral bulb being derived, with the other two branches, from the accessory vessel. Occasionally the accessory pudendal artery is derived from one of the other branches of the hypogastric artery, most frequently the inferior vesical or the obturator.
The Muscular Branches consist of two sets: one given off in the pelvis; the other, as the vessel crosses the ischial spine. The former consists of several small offsets which supply the Levator ani, the Obturator internus, the Piriformis, and the Coccygeus. The branches given off outside the pelvis are distributed to the adjacent parts of the Glutæus maximus and external rotator muscles. They anastomose with branches of the inferior gluteal artery.
The Inferior Hemorrhoidal Artery (a. hæmorrhoidalis inferior) arises from the internal pudendal as it passes above the ischial tuberosity. Piercing the wall of Alcock’s canal it divides into two or three branches which cross the ischiorectal fossa, and are distributed to the muscles and integument of the anal region, and send offshoots around the lower edge of the Glutæus maximus to the skin of the buttock. They anastomose with the corresponding vessels of the opposite side, with the superior and middle hemorrhoidal, and with the perineal artery.
The Perineal Artery (a. perinei; superficial perineal artery) arises from the internal pudendal, in front of the preceding branches, and turns upward, crossing either over or under the Transversus perinæi superficialis, and runs forward, parallel to the pubic arch, in the interspace between the Bulbocavernosus and Ischiocavernosus, both of which it supplies, and finally divides into several posterior scrotal branches which are distributed to the skin and dartos tunic of the scrotum. As it crosses the Transversus perinæi superficialis it gives off the transverse perineal artery which runs transversely on the cutaneous surface of the muscle, and anastomoses with the corresponding vessel of the opposite side and with the perineal and inferior hemorrhoidal arteries. It supplies the Transversus perinæi superficialis and the structures between the anus and the urethral bulb.
The Artery of the Urethral Bulb (a. bulbi urethræ) is a short vessel of large caliber which arises from the internal pudendal between the two layers of fascia of the urogenital diaphragm; it passes medialward, pierces the inferior fascia of the urogenital diaphragm, and gives off branches which ramify in the bulb of the urethra and in the posterior part of the corpus cavernosum urethræ. It gives off a small branch to the bulbo-urethral gland.
The Urethral Artery (a. urethralis) arises a short distance in front of the artery of the urethral bulb. It runs forward and medialward, pierces the inferior fascia of the urogenital diaphragm and enters the corpus cavernosum urethræ, in which it is continued forward to the glans penis.
The Deep Artery of the Penis (a. profunda penis; artery to the corpus cavernosum), one of the terminal branches of the internal pudendal, arises from that vessel while it is situated between the two fasciæ of the urogenital diaphragm; it pierces the inferior fascia, and, entering the crus penis obliquely, runs forward in the center of the corpus cavernosum penis, to which its branches are distributed.
The Dorsal Artery of the Penis (a. dorsalis penis) ascends between the crus penis and the pubic symphysis, and, piercing the inferior fascia of the urogenital diaphragm, passes between the two layers of the suspensory ligament of the penis, and runs forward on the dorsum of the penis to the glans, where it divides into two branches, which supply the glans and prepuce. On the penis, it lies between the dorsal nerve and deep dorsal vein, the former being on its lateral side. It supplies the integument and fibrous sheath of the corpus cavernosum penis, sending branches through the sheath to anastomose with the preceding vessel.
The internal pudendal artery in the female is smaller than in the male. Its origin and course are similar, and there is considerable analogy in the distribution of its branches. The perineal artery supplies the labia pudendi; the artery of the bulb supplies the bulbus vestibuli and the erectile tissue of the vagina; the deep artery of the clitoris supplies the corpus cavernosum clitoridis; and the dorsal artery of the clitoris supplies the dorsum of that organ, and ends in the glans and prepuce of the clitoris.
The inferior gluteal artery (a. glutæa inferior; sciatic artery) (544), the larger of the two terminal branches of the anterior trunk of the hypogastric, is distributed chiefly to the buttock and back of the thigh. It passes down on the sacral plexus of nerves and the Piriformis, behind the internal pudendal artery, to the lower part of the greater sciatic foramen, through which it escapes from the pelvis between the Piriformis and Coccygeus. It then descends in the interval between the greater trochanter of the femur and tuberosity of the ischium, accompanied by the sciatic and posterior femoral cutaneous nerves, and covered by the Glutæus maximus, and is continued down the back of the thigh, supplying the skin, and anastomosing with branches of the perforating arteries.
Inside the pelvis it distributes branches to the Piriformis, Coccygeus, and Levator ani; some branches which supply the fat around the rectum, and occasionally take the place of the middle hemorrhoidal artery; and vesical branches to the fundus of the bladder, vesiculæ seminales, and prostate. Outside the pelvis it gives off the following branches:
The Muscular Branches supply the Glutæus maximus, anastomosing with the superior gluteal artery in the substance of the muscle; the external rotators, anastomosing with the internal pudendal artery; and the muscles attached to the tuberosity of the ischium, anastomosing with the posterior branch of the obturator and the medial femoral circumflex arteries.
The Arteria Comitans Nervi Ischiadici is a long, slender vessel, which accompanies the sciatic nerve for a short distance; it then penetrates it, and runs in its substance to the lower part of the thigh.
The Anastomotic is directed downward across the external rotators, and assists in forming the so-called crucial anastomosis by joining with the first perforating and medial and lateral femoral circumflex arteries.
The iliolumbar artery (a. iliolumbalis) a branch of the posterior trunk of the hypogastric, turns upward behind the obturator nerve and the external iliac vessels, to the medial border of the Psoas major, behind which it divides into a lumbar and an iliac branch.
The Lumbar Branch (ramus lumbalis) supplies the Psoas major and Quadratus lumborum, anastomoses with the last lumbar artery, and sends a small spinal branch through the intervertebral foramen between the last lumbar vertebra and the sacrum, into the vertebral canal, to supply the cauda equina.
The Iliac Branch (ramus iliacus) descends to supply the Iliacus; some offsets, running between the muscle and the bone, anastomose with the iliac branches of the obturator; one of these enters an oblique canal to supply the bone, while others run along the crest of the ilium, distributing branches to the gluteal and abdominal muscles, and anastomosing in their course with the superior gluteal, iliac circumflex, and lateral femoral circumflex arteries.
The superior, of large size, passes medialward, and, after anastomosing with branches from the middle sacral, enters the first or second anterior sacral foramen, supplies branches to the contents of the sacral canal, and, escaping by the corresponding posterior sacral foramen, is distributed to the skin and muscles on the dorsum of the sacrum, anastomosing with the superior gluteal.
The inferior runs obliquely across the front of the Piriformis and the sacral nerves to the medial side of the anterior sacral foramina, descends on the front of the sacrum, and anastomoses over the coccyx with the middle sacral and opposite lateral sacral artery. In its course it gives off branches, which enter the anterior sacral foramina; these, after supplying the contents of the sacral canal, escapes by the posterior sacral foramina, and are distributed to the muscles and skin on the dorsal surface of the sacrum, anastomosing with the gluteal arteries.
The superior gluteal artery (a. glutæa superior; gluteal artery) (544) is the largest branch of the hypogastric, and appears to be the continuation of the posterior division of that vessel. It is a short artery which runs backward between the lumbosacral trunk and the first sacral nerve, and, passing out of the pelvis above the upper border of the Piriformis, immediately divides into a superficial and a deep branch. Within the pelvis it gives off a few branches to the Iliacus, Piriformis, and Obturator internus, and just previous to quitting that cavity, a nutrient artery which enters the ilium.
The superficial branch enters the deep surface of the Glutæus maximus, and divides into numerous branches, some of which supply the muscle and anastomose with the inferior gluteal, while others perforate its tendinous origin, and supply the integument covering the posterior surface of the sacrum, anastomosing with the posterior branches of the lateral sacral arteries.
The deep branch lies under the Glutæus medius and almost immediately subdivides into two. Of these, the superior division, continuing the original course of the vessel, passes along the upper border of the Glutæus minimus to the anterior superior spine of the ilium, anastomosing with the deep iliac circumflex artery and the ascending branch of the lateral femoral circumflex artery. The inferior division crosses the Glutæus minimus obliquely to the greater trochanter, distributing branches to the Glutæi and anastomoses with the lateral femoral circumflex artery. Some branches pierce the Glutæus minimus and supply the hip-joint.
The external iliac artery (539) is larger than the hypogastric, and passes obliquely downward and lateralward along the medial border of the Psoas major, from the bifurcation of the common iliac to a point beneath the inguinal ligament, midway between the anterior superior spine of the ilium and the symphysis pubis, where it enters the thigh and becomes the femoral artery.
Relations.—In front and medially, the artery is in relation with the peritoneum, subperitoneal areolar tissue, the termination of the ileum and frequently the vermiform process on the right side, and the sigmoid colon on the left, and a thin layer of fascia, derived from the iliac fascia, which surrounds the artery and vein. At its origin it is crossed by the ovarian vessels in the female, and occasionally by the ureter. The internal testicular vessels lie for some distance upon it near its termination, and it is crossed in this situation by the external testicular branch of the genitofemoral nerve and the deep iliac circumflex vein; the ductus deferens in the male, and the round ligament of the uterus in the female, curve down across its medial side. Behind, it is in relation with the medial border of the Psoas major, from which it is separated by the iliac fascia. At the upper part of its course, the external iliac vein lies partly behind it, but lower down lies entirely to its medial side. Laterally, it rests against the Psoas major, from which it is separated by the iliac fascia. Numerous lymphatic vessels and lymph glands lie on the front and on the medial side of the vessel.
Collateral Circulation.—The principal anastomoses in carrying on the collateral circulation, after the application of a ligature to the external iliac, are: the iliolumbar with the iliac circumflex; the superior gluteal with the lateral femoral circumflex; the obturator with the medial femoral circumflex; the inferior gluteal with the first perforating and circumflex branches of the profunda artery; and the internal pudendal with the external pudendal. When the obturator arises from the inferior epigastric, it is supplied with blood by branches, from either the hypogastric, the lateral sacral, or the internal pudendal. The inferior epigastric receives its supply from the internal mammary and lower intercostal arteries, and from the hypogastric by the anastomoses of its branches with the obturator. 105
The inferior epigastric artery (a. epigastrica inferior; deep epigastric artery) (547) arises from the external iliac, immediately above the inguinal ligament. It curves forward in the subperitoneal tissue, and then ascends obliquely along the medial margin of the abdominal inguinal ring; continuing its course upward, it pierces the transversalis fascia, and, passing in front of the linea semicircularis, ascends between the Rectus abdominis and the posterior lamella of its sheath. It finally divides into numerous branches, which anastomose, above the umbilicus, with the superior epigastric branch of the internal mammary and with the lower intercostal arteries (522). As the inferior epigastric artery passes obliquely upward from its origin it lies along the lower and medial margins of the abdominal inguinal ring, and behind the commencement of the spermatic cord. The ductus deferens, as it leaves the spermatic cord in the male, and the round ligament of the uterus in the female, winds around the lateral and posterior aspects of the artery.
Branches.—The branches of the vessel are: the external testicular artery (cremasteric artery), which accompanies the spermatic cord, and supplies the Cremaster and other coverings of the cord, anastomosing with the internal testicular artery (in the female it is very small and accompanies the round ligament); a pubic branch which runs along the inguinal ligament, and then descends along the medial margin of the femoral ring to the back of the pubis, and there anastomoses with the pubic branch of the obturator artery; muscular branches, some of which are distributed to the abdominal muscles and peritoneum, anastomosing with the iliac circumflex and lumbar arteries; branches which perforate the tendon of the Obliquus externus, and supply the integument, anastomosing with branches of the superficial epigastric.
Peculiarities.—The origin of the inferior epigastric may take place from any part of the external iliac between the inguinal ligament and a point 6 cm. above it; or it may arise below this ligament, from the femoral. It frequently springs from the external iliac, by a common trunk with the obturator. Sometimes it arises from the obturator, the latter vessel being furnished by the hypogastric, or it may be formed of two branches, one derived from the external iliac, the other from the hypogastric.
The deep iliac circumflex artery (a. circumflexa ilium profunda) arises from the lateral aspect of the external iliac nearly opposite the inferior epigastric artery. It ascends obliquely lateralward behind the inguinal ligament, contained in a fibrous sheath formed by the junction of the transversalis fascia and iliac fascia, to the anterior superior iliac spine, where it anastomoses with the ascending branch of the lateral femoral circumflex artery. It then pierces the transversalis fascia and passes along the inner lip of the crest of the ilium to about its middle, where it perforates the Transversus, and runs backward between that muscle and the Obliquus internus, to anastomose with the iliolumbar and superior gluteal arteries. Opposite the anterior superior spine of the ilium it gives off a large branch, which ascends between the Obliquus internus and Transversus muscles, supplying them, and anastomosing with the lumbar and inferior epigastric arteries.
External iliac vein is continuation of femoral vein and receives blood from all veins of lower limb. Inferior epigastric vein and deep circumflexа ilei vein empties into external iliac vein under inguinal ligament.
The external iliac vein (v. iliaca externa), the upward continuation of the femoral vein, begins behind the inguinal ligament, and, passing upward along the brim of the lesser pelvis, ends opposite the sacroiliac articulation, by uniting with the hypogastric vein to form the common iliac vein. On the right side, it lies at first medial to the artery: but, as it passes upward, gradually inclines behind it. On the left side, it lies altogether on the medial side of the artery. It frequently contains one, sometimes two, valves.
The Inferior Epigastric Vein (v. epigastrica inferior; deep epigastric vein) is formed by the union of the venæ comitantes of the inferior epigastric artery, which communicate above with the superior epigastric vein; it joins the external iliac about 1.25 cm. above the inguinal ligament.
The Deep Iliac Circumflex Vein (v. circumflexa ilium profunda) is formed by the union of the venæ comitantes of the deep iliac circumflex artery, and joins the external iliac vein about 2 cm. above the inguinal ligament.
The hypogastric vein (v. hypogastrica; internal iliac vein) begins near the upper part of the greater sciatic foramen, passes upward behind and slightly medial to the hypogastric artery and, at the brim of the pelvis, joins with the external iliac to form the common iliac vein.
Tributaries.—With the exception of the fetal umbilical vein which passes upward and backward from the umbilicus to the liver, and the iliolumbar vein which usually joins the common iliac vein, the tributaries of the hypogastric vein correspond with the branches of the hypogastric artery. It receives (a) the gluteal, internal pudendal, and obturator veins, which have their origins outside the pelvis; (b) the lateral sacral veins, which lie in front of the sacrum; and (c) the middle hemorrhoidal, vesical, uterine, and vaginal veins, which originate in venous plexuses connected with the pelvic viscera.
1. The Superior Gluteal Veins (vv. glutaeæ superiores; gluteal veins) are venæ comitantes of the superior gluteal artery; they receive tributaries from the buttock corresponding with the branches of the artery, and enter the pelvis through the greater sciatic foramen, above the Piriformis, and frequently unite before ending in the hypogastric vein.
2. The Inferior Gluteal Veins (vv. glutaeæ inferiores; sciatic veins), or venæ comitantes of the inferior gluteal artery, begin on the upper part of the back of the thigh, where they anastomose with the medial femoral circumflex and first perforating veins. They enter the pelvis through the lower part of the greater sciatic foramen and join to form a single stem which opens into the lower part of the hypogastric vein.
3. The Internal Pudendal Veins (internal pudic veins) are the venæ comitantes of the internal pudendal artery. They begin in the deep veins of the penis which issue from the corpus cavernosum penis, accompany the internal pudendal artery, and unite to form a single vessel, which ends in the hypogastric vein. They receive the veins from the urethral bulb, and the perineal and inferior hemorrhoidal veins. The deep dorsal vein of the penis communicates with the internal pudendal veins, but ends mainly in the pudendal plexus.
4. The Obturator Vein (v. obturatoria) begins in the upper portion of the adductor region of the thigh and enters the pelvis through the upper part of the obturator foramen. It runs backward and upward on the lateral wall of the pelvis below the obturator artery, and then passes between the ureter and the hypogastric artery, to end in the hypogastric vein.
6. The Middle Hemorrhoidal Vein (v. hæmorrhoidalis media) takes origin in the hemorrhoidal plexus and receives tributaries from the bladder, prostate, and seminal vesicle; it runs lateralward on the pelvic surface of the Levator ani to end in the hypogastric vein.
The hemorrhoidal plexus (plexus hæmorrhoidalis) surrounds the rectum, and communicates in front with the vesical plexus in the male, and the uterovaginal plexus in the female. It consists of two parts, an internal in the submucosa, and an external outside the muscular coat. The internal plexus presents a series of dilated pouches which are arranged in a circle around the tube, immediately above the anal orifice, and are connected by transverse branches.
The lower part of the external plexus is drained by the inferior hemorrhoidal veins into the internal pudendal vein; the middle part by the middle hemorrhoidal vein which joins the hypogastric vein; and the upper part by the superior hemorrhoidal vein which forms the commencement of the inferior mesenteric vein, a tributary of the portal vein. A free communication between the portal and systemic venous systems is established through the hemorrhoidal plexus.
The veins of the hemorrhoidal plexus are contained in very loose, connective tissue, so that they get less support from surrounding structures than most other veins, and are less capable of resisting increased blood-pressure.
The pudendal plexus (plexus pudendalis; vesicoprostatic plexus) lies behind the arcuate public ligament and the lower part of the symphysis pubis, and in front of the bladder and prostate. Its chief tributary is the deep dorsal vein of the penis, but it also receives branches from the front of the bladder and prostate. It communicates with the vesical plexus and with the internal pudendal vein and drains into the vesical and hypogastric veins. The prostatic veins form a well-marked prostatic plexus which lies partly in the fascial sheath of the prostate and partly between the sheath and the prostatic capsule. It communicates with the pudendal and vesical plexuses.
The vesical plexus (plexus vesicalis) envelops the lower part of the bladder and the base of the prostate and communicates with the pudendal and prostatic plexuses. It is drained, by means of several vesical veins, into the hypogastric veins.
The Dorsal Veins of the Penis (vv. dorsales penis) are two in number, a superficial and a deep. The superficial vein drains the prepuce and skin of the penis, and, running backward in the subcutaneous tissue, inclines to the right or left, and opens into the corresponding superficial external pudendal vein, a tributary of the great saphenous vein. The deep vein lies beneath the deep fascia of the penis; it receives the blood from the glans penis and corpora cavernosa penis and courses backward in the middle line between the dorsal arteries; near the root of the penis it passes between the two parts of the suspensory ligament and then through an aperture between the arcuate pubic ligament and the transverse ligament of the pelvis, and divides into two branches, which enter the pudendal plexus. The deep vein also communicates below the symphysis pubis with the internal pudendal vein.
The uterine plexuses lie along the sides and superior angles of the uterus between the two layers of the broad ligament, and communicate with the ovarian and vaginal plexuses. They are drained by a pair of uterine veins on either side: these arise from the lower part of the plexuses, opposite the external orifice of the uterus, and open into the corresponding hypogastric vein.
The vaginal plexuses are placed at the sides of the vagina; they communicate with the uterine, vesical, and hemorrhoidal plexuses, and are drained by the vaginal veins, one on either side, into the hypogastric veins.
The common iliac veins (vv. iliacæ communes) are formed by the union of the external iliac and hypogastric veins, in front of the sacroiliac articulation; passing obliquely upward toward the right side, they end upon the fifth lumbar vertebra, by uniting with each other at an acute angle to form the inferior vena cava. The right common iliac is shorter than the left, nearly vertical in its direction, and ascends behind and then lateral to its corresponding artery. The left common iliac, longer than the right and more oblique in its course, is at first situated on the medial side of the corresponding artery, and then behind the right common iliac. Each common iliac receives the iliolumbar, and sometimes the lateral sacral veins. The left receives, in addition, the middle sacral vein. No valves are found in these veins.
The Middle Sacral Veins (vv. sacrales mediales) accompany the corresponding artery along the front of the sacrum, and join to form a single vein, which ends in the left common iliac vein; sometimes in the angle of junction of the two iliac veins.
Peculiarities.—The left common iliac vein, instead of joining with the right in its usual position, occasionally ascends on the left side of the aorta as high as the kidney, where, after receiving the left renal v
ein, it crosses over the aorta, and then joins with the right vein to form the vena cava. In these cases, the two common iliacs are connected by a small communicating branch at the spot where they are usually united.