Chapter 41
Section 41 of Gray's Anatomy, Part 3. All LibriVox recordings are in the public domain. For more information, or to volunteer, please visit LibriVox.org. Recording by Eric Hale. Anatomy of the Human Body, Part 3 by Henry Gray.
The Veins of the Lower Extremity, Abdomen and Pelvis. Part 2. The Hemorrhoidal Plexus surrounds the rectum and communicates in front with the Vesicle 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 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 vesicle plexus and with the internal pudendal vein, and drains into the vesicle 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 vesicle plexuses. The vesicle plexus 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 vesicle veins into the hypogastric veins. The dorsal veins of the 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. The vaginal plexuses 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, vesicle, and hemorrhoidal plexuses, and are drained by the vaginal veins, one on either side into the hypogastric veins. The common iliac veins 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 ilial lumbar, 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 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 vein, 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. The inferior vena cava 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 medial word for about 2.5 cm,
and, piercing the fibrous pericardium, passes behind the serous pericardium to open into the lower and back part of the right atrium. In front of its atrial orifice is a semi-lunar valve, termed the valve of the inferior vena cava. This is rudimentary in the adult,
but is of large size and exercises an important function in the fetus. 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 spermatic 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 cruss 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 criss of the diaphragm, and the caudate lobe of the liver.
The thoracic portion is only about 2.5 cm in length, and is situated partly inside and partly outside the pericardial sac. The extra pericardial part is separated from the right pleura and lung by a fibrous band, named the right phrenicoparacardiac ligament.
This ligament, often feebly marked, is attached below to the margin of the vena cava opening in the diaphragm, and above to the pericardium in front of and behind the root of the right lung. The intrapericardiac part is very short, and is covered anterior laterally by the serous layer of the pericardium.
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 ozygous 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. Tributeries The inferior vena cava receives the following veins. Lumbar Renal
Inferior phrenic, right spermatic or ovarian Super renal Hepatic The lumbar veins, four in number on each side, collect the blood by dorsal tributaries from the muscles and entagament 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 vertebrae, 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 process of the lumbar vertebrae,
and is called the ascending lumbar. It forms the most frequent origin of the corresponding ozygous or hemiozygous vein, and serves to connect the common iliac, ilial lumbar, and ozygous or hemiozygous veins of its own side of the body. The spermatic veins emerge from the back of the testes,
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 spermatic 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 spermatic veins are provided with valves. The left spermatic vein passes behind the iliac colon,
and is thus exposed to pressure from the contents of that part of the bowel. The ovarian veins 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 spermatic veins in the male.
Valves are occasionally found in these veins. Like the uterine veins, they become much enlarged during pregnancy. The renal veins 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 spermatic 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 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 follow the course of the inferior phrenic arteries. 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 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. End of section 41 Recording by Eric Hale
