 Section 17 of Grey's Anatomy Part 5. This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org. Recording by Anne Boulet. Anatomy of the Human Body Part 5 by Henry Gray. The Abdomen Part 2. Horizontal Disposition of the Peritoneum. Below the transverse colon, the arrangement is simple, as it includes only the main cavity. Above the level of the transverse colon, it is more complicated on account of the existence of the Omental Bersa. Below the transverse colon, it may be considered in the two regions, V's, in the pelvis, and in the abdomen proper. In the pelvis, the peritoneum here follows closely the surfaces of the pelvic viscera and the inequalities of the pelvic walls, and presents important differences in the two sexes. A. In the male, it encircles the sigmoid colon, from which it is reflected to the posterior wall of the pelvis as a fold, the sigmoid mesocolon. It then leaves the sides, and finally, the front of the rectum, and is continued on to the upper ends of the seminal vesicles and the bladder. On either side of the rectum, it forms a fossa, the parorectal fossa, which varies in size with the distension of the rectum. In front of the rectum, the peritoneum forms the rectovesicle excavation, which is limited laterally by the peritoneal folds extending from the sides of the bladder to the rectum and the sacrum. These folds are known from their position as the rectovesicle or saprogenital folds. The peritoneum of the anterior pelvic wall covers the superior surface of the bladder, and on either side of this viscous forms a depression, termed the paravessicle fossa, which is limited laterally by the fold of peritoneum covering the ductus deference. The size of this fossa is dependent on the state of distension of the bladder. When the bladder is empty, a variable fold of peritoneum, the pleca vesicalis transversa, divides the fossa into two portions. On the peritoneum between the paravessicle and parorectal fossa, the only elevations are those produced by the ureters and the hypogastric vessels. B. In the female, parorectal and paravessicle fossa, similar to those in the male, are present. The lateral limit of the paravessicle fossa is the peritoneum investing the round ligament of the uterus. The rectovesicle excavation is, however, divided by the uterus and vagina, into a small anterior vesicouterine and a large, deep posterior rectouterine excavation. The sacrogenital folds form the margins of the bladder and are continued on to the back of the uterus to form a transverse fold, the torus uterinas. The broad ligaments extend from the size of the uterus to the lateral walls of the pelvis. They contain in their free margins the uterine tubes and in their posterior layers, the ovaries. Below, the broad ligaments are continuous with the peritoneum on the lateral walls of the pelvis. On the lateral pelvic wall behind the attachment of the broad ligament, in the angle between the elevations produced by the diverging hypogastric and external iliac vessels is a slight fossa, the ovarian fossa, in which the ovary normally lies. In the lower abdomen, starting with the linea alba below the level of the transverse colon and tracing the continuity of the peritoneum in a horizontal direction to the right, the membrane covers the inner surface of the abdominal wall almost as far as the lateral border of the quadratus lumborum. It encloses the cecum and the vermaform process and is reflected over the sides and front of the ascending colon. It may then be traced over the duodenum, psoces major and inferior vena cava toward the middle line when sit passes along the mesentery vessels to invest the small intestine and back again to the large vessels in front of the vertebral column forming the mesentery between the layers of which are contained the mesentery blood vessels, lacteals and glands. It is then continued over the left psoces. It covers the sides and front of the descending colon and reaching the abdominal wall is carried on it to the middle line. The upper abdomen. Above the transverse colon, the elemental versa is super added to the general sac and the communication of the two cavities with one another. Through the epiploic foreman can be demonstrated. Main cavity. Commencing on the posterior abdominal wall at the inferior vena cava, the peritoneum may be followed to the right over the front of the super renal gland and the upper part of the right kidney onto the anterior lateral abdominal wall. From the middle line of the anterior wall, a backwardly directed fold encircles the obliterated umbilical vein and forms the falciform ligament of the liver. Continuing to the left, the peritoneum lines the anterior lateral abdominal wall and covers the lateral part of the front of the left kidney and is reflected to the posterior border of the hilus of the spleen as the posterior layer of the frontocleolienal ligament. It can then be traced around the surface of the spleen to the front of the hilus and then to the cardiac end of the greater curvature of the stomach as the anterior layer of the gastro-lienal ligament. It covers the anterior superior surfaces of the stomach and commencement of the duodenum and extends up from the lesser curvature of the stomach to the liver as the anterior layer of the lesser omentum. B. Omental bursa. Bursa omentalis. Lesser peritoneal sac. On the posterior abdominal wall, the peritoneum of the general cavity is continuous with that of the omental bursa in front of the inferior vena cava. Starting from here, the bursa may be traced across the aorta and over the medial part of the front of the left kidney and diaphragm to the hilus of the spleen as the anterior layer of the frontocleolienal ligament. From the spleen, it is reflected to the stomach as the posterior layer of the gastrosplenic ligament. It covers the posterior inferior surfaces of the stomach and commencement of the duodenum and extends upward to the liver as the posterior layer of the lesser omentum. The right margin of this layer is continuous around the hepatic artery, bile duct, and portal vein with the wall of the general cavity. The epiploic foramen. Foramen epiploacum. Foramen of Winslow. Is the passage of communication between the general cavity and the omental bursa. It is bounded in front by the free border of the lesser omentum with the common bile duct, hepatic artery, and portal vein between its two layers. Behind by the peritoneum covering the inferior vena cava. Above by the peritoneum on the caudate process of the liver. And below by the peritoneum covering the commencement of the duodenum and the hepatic artery. The latter passing forward below the foramen before ascending between the two layers of the lesser omentum. The boundaries of the omental bursa will now be evident. It is bounded in front from above downward by the caudate lobe of the liver. The lesser omentum, the stomach, and the anterior two layers of the greater omentum. Behind it is limited from below upward by the two posterior layers of the greater omentum. The transverse colon and the ascending layer of the transverse mesocolon. The upper surface of the pancreas. The left superrenal gland and the upper end of the left kidney. To the right of the esophageal opening of the stomach. It is formed by that part of the diaphragm which supports the caudate lobe of the liver. Laterally, the bursa extends from the epiploic foramen to the spleen. Where it is limited by the phrenocoleanol and gastroleanoligaments. The omental bursa, therefore, consists of a series of pouches or recesses to which the following terms are applied. One, the vestibule. A narrow channel continued from the epiploic foramen over the head of the pancreas to the gastropancreatic fold. This fold extends from the omental turbosity of the pancreas to the right side of the fundus of the stomach. And contains the left gastric artery and coronary vein. Two, the superior omental recess between the caudate lobe of the liver and the diaphragm. Three, the leanyl recess between the spleen and the stomach. Four, the inferior omental recess which comprises the remainder of the bursa. In the fetus, the bursa reaches as low as the free margin of the greater omentum. But in the adult, its vertical extent is usually more limited owing to adhesions between the layers of the omentum. During a considerable part of fetal life, the transverse colon is suspended from the posterior abdominal lobe by a mesentery of its own. The two posterior layers of the greater omentum passing at this stage in front of the colon. This condition occasionally persists throughout life, but as a rule adhesion occurs between the mesentery of the transverse colon and the posterior layer of the greater omentum. With the result that the colon appears to receive its peritoneal covering by the splitting of the two posterior layers of the latter fold. In the adult, the omental bursa intervenes between the stomach and the structures on which that viscous lies and performs therefore the functions of the cirrus bursa for the stomach. Numerous peritoneal folds extend between the various organs or connect them to the parietes. They serve to hold the viscera in position and, at the same time, enclose the vessels and nerves proceeding to them. They are grouped under the three headings of ligaments, omenta, and mesenteries. The ligaments will be described with their respective organs. There are two omenta, the lesser and the greater. The lesser omentum, omentum minus, small omentum, gastro-hepatic omentum is the duplicature which extends to the liver from the lesser curvature of the stomach and the commencement of the duodenum. It is extremely thin and is continuous with the two layers of peritoneum which cover respectively the anterior, superior, and posterior inferior surfaces of the stomach and first part of the duodenum. When these two layers reach the lesser curvature of the stomach and the upper border of the duodenum, they join together and ascend as a double fold to the porta of the liver. To the left of the porta, the fold is attached to the bottom of the fossa for the ductus venosis, along which it is carried to the diaphragm, where the two layers separate to embrace the end of the esophagus. At the right border of the omentum, the two layers are continuous and form a free margin which constitutes the anterior boundary of the epaplotic for omen. The portion of the lesser omentum extending between the liver and stomach is termed the hypo-gastric ligament, while that between the liver and the duodenum is the hepato-duodenal ligament. Between the two layers of the lesser omentum, close to the right free margin are the hepatic artery, the common bile duct, the portal vein, lymphatics, and the hepatic plexus of nerves. All these structures being enclosed in the fibrous capsule, glistens capsule. Between the layers of the lesser omentum, where they are attached to the stomach, run the right and left gastric vessels. The greater omentum, omentum mages, great omentum, gastrocolic omentum, is the largest peritoneal fold. It consists of a double sheet of peritoneum, folded on itself so that it is made up of four layers. The two layers which descend from the stomach and commencement of the duodenum pass in front of the small intestines, sometimes as low down as the pelvis. They then turn upon themselves and descend again as far as the transverse colon, where they separate and enclose that part of the intestine. These individual layers may be easily demonstrated in the young subject, but in the adult, they are more or less inseparably blended. The left border of the greater omentum is continuous with the gastro-lienal ligament. Its right border extends as far as the commencement of the duodenum. The greater omentum is usually thin, presents a cribiform appearance, and usually contains some adipose tissue, which in fat people accumulates inconsiderable quantity. Between its two anterior layers, a short distance from the greater curvature of the stomach, is the anastomosis between the right and left gastroepoplotic vessels. The mesentaries are the mesentary proper, the transverse mesocolon, and the sigmoid mesocolon. In addition to these, there are sometimes present an ascending and a descending mesocolon. The mesentary proper, mesentarium, is the broad, fan-like fold of peritoneum, which connects the convolutions of the jejunum and ilium with the posterior wall of the abdomen. Its root, the part connected with the structures in front of the vertebral column, is narrow, about 15 centimeters long, and is directed obliquely from the duano-gejunal flexure at the left side of the second lumbar vertebra to the right sacroiliac articulation. Its intestinal border is about six meters long, and here the two layers separate to enclose the intestine and form its peritoneal coat. It is narrow above, but widens rapidly to about 20 centimeters and is thrown into various plates or folds. It suspends the small intestine and contains between its layers the intestinal branches of the superior mesentary artery, with their accompanying veins and plexuses of nerves, the lacteal vessels, and mesentary lymph glands. The transverse mesocolon, mesocolon transversus, is a broad fold, which connects the transverse colon to the posterior wall of the abdomen. It is continuous with the two posterior layers of the greater omentum, which, after separating to surround the transverse colon, join behind it and are continued backward to the vertebral column, where they diverge in front of the anterior border of the pancreas. This fold contains between its layers the vessels which supply the transverse colon. The sigmoid mesocolon, mesocolon sigmoidium, is the fold of peritoneum which retains the sigmoid colon in connection with the pelvic wall. Its line of attachment forms a V-shaped curve, the apex of the curve being placed about the point of division of the left common iliac artery. The curve being on the medial side of the left psocis major, and runs upward and backward to the apex, from which it bends sharply downward, and ends in the medial plane at the level of the third sacral vertebra. The sigmoid and superior hemorrhoidal vessels run between the two layers of this fold. In most cases, the peritoneum covers only the front and sides of the ascending and descending parts of the colon. Sometimes, however, these are surrounded by the cirrus membrane, and attached to the posterior abdominal wall by an ascending and a descending mesocolon, respectively. A fold of peritoneum, the phrenococolic ligament, is continued from the left colic flexure to the diaphragm opposite the 10th and 11th ribs. It passes below and serves to support the spleen, and therefore has received the name of cystinoculum leannus. The appendices epicloacae are small pouches of the peritoneum filled with fat and situated along the colon and upper part of the rectum. They are chiefly appended to the transverse and sigmoid parts of the colon. Peritoneal recesses or fose, retroperitoneal fose. In certain parts of the abdominal cavity, there are recesses of peritoneum forming cul-de-sacs or pouches, which are of surgical interest in connection with the possibility of the occurrence of retroperitoneal herniae. The largest of these is the omental bursa, already described, but several others of smaller size require mention and may be divided into three groups. These, duodenal, cecal, and intersigmoid. Duodenal fose, three are fairly constant. The inferior duodenal fosa, present in from 70 to 75% of cases, is situated opposite the third lumbar vertebra on the left side of the ascending portion of the duodenum. Its opening is directed upward and is bounded by a thin, sharp fold of peritoneum with a concave margin, called a duodenum mesacolic fold. The tip of the index finger introduced into the fosa under the fold passes some little distance behind the ascending portion of the duodenum. B. The superior duodenal fosa, present in from 40 to 50% of cases, often co-exists with the inferior one and its orifice looks downward. It lies on the left of the ascending portion of the duodenum in front of the second lumbar vertebra and behind a sickle-shaped form of peritoneum. The duodenal jejunal fold and has a depth of about 2 cm. C. The duodenal jejunal fosa exists in from 15 to 20% of cases, but has never yet been found in conjunction with the other forms of duodenal fose. It can be seen by pulling the jejunum downward and to the right after the transverse colon has been pulled upward. It is bounded above by the pancreas, to the right by the aorta, and to the left by the kidney. Beneath is the left renal vein. It has a depth of about 2 to 3 cm. And its orifice, directed downward and to the right, is nearly circular and will admit the tip of the little finger. C. Sequel fosae, pericycle folds or fosae. There are three principal pouches or recesses in the neighborhood of the cecum. A. The superior iliocecal fosa is formed by a fold of peritoneum, arching over the branch of the iliocholic artery which supplies the iliocholic junction. The fosa is a narrow chink situated between the mesentery of the small intestine, the ilium, and the small portion of the cecum behind. B. The inferior iliocecal fosa is situated behind the angle of the junction of the ilium and cecum. It is formed by the iliocecal fold of peritoneum, bloodless fold of travesse. The upper border of which is fixed to the ilium, opposite its mesentery attachment, while the lower border, passing over the iliocecal junction, joins the mesentery of the vermiform process and sometimes the process itself. Between this fold and the mesentery of the vermiform process is the inferior iliocecal fosa. It is bounded above by the posterior surface of the ilium and the mesentery, in front and below by the iliocecal fold, and behind by the upper part of the mesentery of the vermiform process. C. The cecal fosa is situated immediately behind the cecum, which has to be raised to bring it into view. It varies much in size and extent. In some cases, it is sufficiently large to admit the index finger and extends upward behind the ascending colon in the direction of the kidney. In others, it is merely a shallow depression. It is bounded on the right by the cecal fold, which is attached by one edge of the abdominal wall, from the lower border of the kidney to the iliac fosa, and by the other to the posterior lateral aspect of the colon. In some instances, additional fosae, the retrocecal fosae, are present. The intersigmoid fosa, recesses intersigmoideus, is constant in the fetus and during infancy, but disappears in a certain percentage of cases as age advances. Upon drawing the sigmoid colon upward, the left surface of the sigmoid mesocolon is exposed, and on it will be seen a funnel-shaped recess of the peritoneum, lying on the external iliac vessels in the interspace between the psoces and iliacus muscles. This is the orifice leading to the intersigmoid fosa, which lies behind the sigmoid mesocolon and in front of the parietal peritoneum. The fosa varies in size. In some instances, it is a mere dimple, whereas in others, it will admit the whole of the index finger. End of section 17. The stomach is the most dilated part of the digestive tube and is situated between the end of the esophagus and the beginning of the small intestine. It lies in the epigastric, umbilical, and left hypochondriac regions of the abdomen and occupies a recess bounded by the upper abdominal viscera and completed in front and on the left side by the anterior abdominal wall and the diaphragm. The shape and position of the stomach are so greatly modified by changes within itself and in the surrounding viscera that no one form can be described as typical. The shape and position of the stomach are so greatly modified by changes within itself and in the surrounding viscera that no one form can be described as typical. The chief modifications are determined by, one, the amount of the stomach contents, two, the stage with the digestive process has reached, three, the degree of development of the gastric musculature, and four, the condition of the adjacent intestines. It is, however, possible by comparing a series of stomachs to determine certain markings more or less common to all. The stomach presents two openings, two borders or curvatures, and two surfaces. Openings. The opening by which the esophagus communicates with the stomach is known as the cardiac orifice and is situated on the left of the middle line at the level of the tenth thoracic vertebra. The short abdominal portion of the esophagus, anterum cardiacum, is conical in shape and curved sharply to the left, the base of the cone being continuous with the cardiac orifice of the stomach. The right margin of the esophagus is continuous with the lesser curvature of the stomach while the left margin joins the greater curvature at an acute angle, termed the incisura cardiaca. The pyloric orifice communicates with the duodenum and its position is usually indicated on the surface of the stomach by a circular groove, the duodenal pyloric constriction. This orifice lies to the right of the middle line at the level of the upper border of the first lumbar vertebra. Curvatures. The lesser curvature, curvature of ventricular minor, extending between the cardiac and pyloric orifices, forms the right or posterior border of the stomach. It descends as a continuation of the right margin of the esophagus in front of the fibers of the right cruise of the diaphragm, and then, turning to the right, it crosses the first lumbar vertebra and ends at the pylorus. Nearer its pyloric than its cardiac end is a well-marked notch, the incisura angularis, which varies somewhat in position with the state of distention of the viscous. It serves to separate the stomach into a right and left portion. The lesser curvature gives attachment to the two layers of the hepatogastric ligament, and between these two layers are the left gastric artery and the right gastric branch of the hepatic artery. The greater curvature, curvature of ventricular major, is directed mainly forward, and is four or five times as long as the lesser curvature. Starting from the cardiac orifice at the incisura cardiaca, it forms an arch backward-upward into the left. The highest point of the convexity is on a level with the sixth left costal cartilage. From this level, it may be followed downward and forward with a slight convexity to the left, as low as the cartilage of the ninth rib. It then turns to the right, to the end of the pylorus. Directly opposite the incisura angularis of the lesser curvature, the greater curvature presents a dilation, which is the left extremity of the pyloric part. The dilation is limited on the right by a slight groove, the sulcus intermedius, which is about 2.5 centimeters from the duodenal pyloric constriction. The portion between the sulcus intermedius and the duodenal pyloric constriction is termed the pyloric antrum. At its commencement, the greater curvature is covered by peritoneum, continuous with that covering the front of the organ. The left part of the curvature gives attachment to the gastrolienal ligament, and to its anterior portion are attached the two layers of the greater omentum, separated from each other by the gastroepoplemic vessels. Surfaces. When the stomach is in the contracted condition, its surfaces are directed upward and downward, respectively. But when the viscous is descended, they are directed forward and backward. They may therefore be described as antero-superior and posturo-inferior. Antero-superior surface. The left half of this surface is in contact with the diaphragm, which separates it from the base of the left lung, the pericardium, and the seventh, eighth, and ninth ribs, and intercostal spaces of the left side. The right half is in relation with the left and quadrate lobes of the liver, and with the anterior abdominal wall. When the stomach is empty, the transverse colon may lie on the front part of this surface. The whole surface is covered by peritoneum. The posturo-inferior surface is in relation with the diaphragm, the spleen, the left suprarenal gland, the upper part of the front of the left kidney, the anterior surface of the pancreas, the left colic flexure, and the upper layer of the transverse mesocolon. These structures form a shallow bed, the stomach bed, on which the viscous rests. The transverse mesocolon separates the stomach from the duodenal gejunal flexure and the small intestine. The posturo-inferior surface is covered by peritoneum, except over a small area close to the cardiac orifice. This area is limited by the lines of attachment of the gastrophrenic ligament and lies in opposition with the diaphragm and frequently with the upper portion of the left suprarenal gland. Component parts of the stomach. A plane passing through the incisor angularis on the lesser curvature and the left limit of the opposed dilation on the greater curvature divides the stomach into a left portion or body and a right or pyloric portion. The left portion of the body is known as the fundus, and it's marked off from the remainder of the body by a plane passing horizontally through the cardiac orifice. The pyloric portion is divided by a plane through the sulcus intermedius at right angles to the long axis of this portion. The part to the right of this plane is the pyloric antrum. If the stomach be examined during the process of digestion, it will be found divided by a muscular constriction into a large dilated left portion and a narrow contracted tubular right portion. The constriction is in the body of the stomach and does not follow any of the anatomical landmarks. Indeed, it shifts gradually toward the left as digestion progresses. That is, more of the body is gradually absorbed into the tubular part. Position of the stomach. The position of the stomach varies with the posture, with the amount of the stomach contents and with the condition of the intestines on which it rests. In the erect posture, the empty stomach is somewhat J-shaped. The part above the cardiac orifice is usually distended with gas. The pylorus descends to the level of the second lumbar vertebra and the most dependent part of the stomach is at the level of the umbilicus. Variation in the amount of its contents affects mainly the cardiac portion. The pyloric portion remaining in a more or less contracted condition during the process of digestion. As the stomach fills, it tends to expand forward and downward in the direction of least resistance. But when this is interfered with by a distended condition of the colon or intestines, the fundus presses upward on the liver and diaphragm and gives rise to the feelings of repression and palpitation complained of in such cases. His and Cunningham have shown by hardening the viscera in situ that the contracted stomach has a sickle shape, the fundus looking directly backward. The surfaces are directed upward and downward, the upper surface having, however, a gradual downward slope to the right. The greater curvature is in front and at a slightly higher level than the lesser. The position of the full stomach depends, as already indicated, on the state of the intestines. When these are empty, the fundus expands vertically and so forward. The pylorus is displaced toward the right and the whole organ assumes an oblique position so that its surfaces are directed more forward and backward. The lowest part of the stomach is at the pyloric vestibule which reaches into the region of the umbilicus. Where the intestines interfere with the downward expansion of the fundus, the stomach retains the horizontal position which is characteristic of the contracted viscous. Examination of the stomach during life by X-rays has confirmed these findings and has demonstrated that, in the erect posture, the full stomach usually presents a hook-like appearance, the long axis of the clinical fundus being directed downward, medialward, and forward toward the umbilicus, while the pyloric portion curves upward to the duodenal pyloric junction. Interior of the stomach When examined after death, the stomach is usually fixed at some temporary stage of the digestive process. A common form is shown in Figure 1050. If the viscous be laid open by a section through the plane of its two curvatures, it is seen to consist of two segments. A, a large globular portion to the left and B, a narrow tubular part on the right. These correspond to the clinical subdivisions of fundus and pyloric portions already described and are separated by a constriction which indents the body and greater curvature but does not involve the lesser curvature. To the left of the cardiac orifice is the incisora cardiaca. The projection of this notch into the cavity of the stomach increases as the organ distends and has been supposed to act as a valve preventing regurgitation into the esophagus. In the pyloric portion are seen, A, the elevation corresponding to the incisora angularis and B, the circular projection of the duodenal pyloric constriction which forms the pyloric valve. The separation of the pyloric antrum from the rest of the pyloric part is scarcely indicated. The pyloric valve, valvula pylori, is formed by a reduplication of the mucous membrane of the stomach, covering a muscular ring composed of a thickened portion of the circular layer of the muscular coat. Some of the deeper longitudinal fibers turn in and interlace with the circular fibers of the valve. Structure. The wall of the stomach consists of four coats, cirrus, muscular, areolar and mucous, together with vessels and nerves. The cirrus coat, tunica cirrosa, is derived from the peritoneum and covers the entire surface of the organ, accepting along the greater and lesser curvatures at the points of the attachment of the greater and lesser omenta. Here the two layers of peritoneum leave a small triangular space along which the nutrient vessels and nerves pass. On the posterior surface of the stomach, close to the cardiac orifice, there is also a small area uncovered by peritoneum where the organ is in contact with the under surface of the diaphragm. The muscular coat, tunica muscularis, is situated immediately beneath the cirrus covering, with which it is closely connected. It consists of three sets of smooth muscle fibers, longitudinal, circular and oblique. The longitudinal fibers, stratum longitudinali, are the most superficial and are arranged in two sets. The first set consists of fibers continuous with the longitudinal fibers of the esophagus. They radiate in a stellate manner from the cardiac orifice and are practically all lost before the pyloric portion is reached. The second set commences on the body of the stomach and passes to the right, its fibers becoming more thickly distributed as they approach the pylorus. Some of the more superficial fibers of this set pass on to the duodenum, but the deeper fibers dip inward and interlace with the circular fibers of the pyloric valve. The circular fibers, stratum circulari, form a uniform layer over the whole extent of the stomach beneath the longitudinal fibers. At the pylorus they are most abundant and are aggregated into a circular ring which projects into the lumen and forms with the fold of mucous membrane covering its surface, the pyloric valve. They are continuous with the circular fibers of the esophagus but are sharply marked off from the circular fibers of the duodenum. The oblique fibers, fibri oblique, internal to the circular layer, are limited chiefly to the cardiac end of the stomach where they are disposed as a thick uniform layer covering both surfaces, some passing obliquely from left to right, others from right to left, around the cardiac end. The areolar or submucosa's coat, tila submucosa, consists of a loose areolar tissue connecting the mucous and muscular layers. The mucous membrane, tunica mucosa, is thick and its surface is smooth, soft and velvety. In the fresh state it is of pinkish tinge at the pyloric end and of a red or reddish brown color over the rest of its surface. In infancy it is of a brighter hue, the vascular redness being more marked. It is thin at the cardiac extremity but thicker toward the pylorus. During the contracted state of the organ it is thrown into numerous plates or rugae which for the most part have a longitudinal direction and are most marked toward the pyloric end of the stomach and along the greater curvature. These folds are entirely obliterated when the organ becomes distended. Structure of the mucous membrane When examined with the lens the inner surface of the mucous membrane presents a peculiar honeycomb appearance from being covered with small shallow depressions or avioli of a polygonal or hexagonal form which vary from 0.12 to 0.25 millimeters in diameter. These are the ducts of the gastric glands and at the bottom of each may be seen one or more minute orifices, the openings of the gland tubes. The surface of the mucous membrane is covered by a single layer of columnar epithelium with occasional goblet cells. This epithelium commences very abruptly at the cardiac orifice where there is a sudden transition from the stratified epithelium of the esophagus. The epithelial lining of the gland ducts is of the same character and is continuous with the general epithelial lining of the stomach. The gastric glands. The gastric glands are of three kinds. A. Pyloric, B. Cardiac, and C. Fundus or Oxintic glands. They are tubular in character and are formed of a delicate basement membrane consisting of flattened, transparent, endothelial cells lined by epithelium. The pyloric glands are found in the pyloric portion of the stomach. They consist of two or three short closed tubes opening into a common duct or mouth. These tubes are wavy and are about one half the length of the duct. The duct is lined by columnar cells continuous with the epithelium lining the surface of the mucous membrane of the stomach. The tubes by shorter and more cubical cell which are finally granular. The cardiac glands, few in number, occur close to the cardiac orifice. They are of two kinds. One, simple tubular glands resembling those of the pyloric end of the stomach but with short ducts. Two, compound racemos glands resembling the duodenal glands. The fundus glands are found in the body and fundus of the stomach. They are simple tubes, two or more of which open into a single duct. The duct, however, in these glands is shorter than in the pyloric variety sometimes not amounting to more than one sixth of the whole length of the gland. It is lined throughout by columnar epithelium. The gland tubes are straight and parallel to each other at the point where they open into the duct and firm the neck. The epithelium alters and consists of short columnar or polyhedral granular cells which almost fill the tube so that the lumen becomes suddenly constricted and is continued down as a very fine channel. They are known as the chief or central cells of the glands. Between these cells in the basement membrane larger oval cells which stain deeply with eosin are found. These cells are studded throughout the tube at intervals of heated or varicose appearance. These are known as the parietal or oxyntic cells and they are connected with the lumen by fine channels which run into their substance. Between the glands the mucous membrane consists of a connective tissue framework with lymphoid tissue. In places this later tissue especially in early life is collected into little masses which to a certain extent resemble the solitary nodules of the intestine and are termed the lenticular glands of the stomach. They are not, however, so distinctly circumscribed as the solitary nodules. Beneath the mucous membrane and between it and the submucous coat is a thin stratum of involuntary muscular fiber, muscularis mucosii which in some parts consists only of a single longitudinal layer in others of two layers an inner circular and an outer longitudinal. Vessels and Nerves The arteries supplying the stomach are the left gastric, the right gastric and the right gastroepiploic branches of the hepatic, the left gastroepiploic and short gastric branches of the laenol. They supply the muscular coat, ramify in the submucous coat and are finally distributed to the mucous membrane. The arrangement of the vessels in the mucous membrane is somewhat peculiar. The arteries break up at the base of the gastric tubules into a plexus of fine capillaries which run upward between the tubules with each other and ending in a plexus of larger capillaries which surround the mouths of the tubes and also form hexagonal meshes around the ducts. From these the veins arise and pursue a straight course downward between the tubules to the submucous tissue. They end either in the laenol and superior mesenteric veins or directly in the portal vein. The lymphatics are numerous. They consist of a superficial and a deep set and past the lymph glands found along the two curvatures of the organ. The nerves are the terminal branches of the right and left vagae, the former being distributed upon the back and the latter upon the front part of the organ. A great number of branches from the celiac plexus of the sympathetic are also distributed to it. Nerve plexuses are found in the submucous coat and between the layers of the muscular coat as in the intestine. From these plexuses, fibrils are distributed to the muscular tissue of the membrane. End of section 18 Section 19 of Gray's Anatomy Part 5 This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org Recording by Mark Rocher Anatomy of the Human Body Part 5 by Henry Gray 2G Intestinum tenue The small intestine is a convoluted tube extending from the pylorus to the colic valve where it ends in the large intestine. It is about 7 meters long. Footnote Tree states that in 100 cases the average length of the small intestine in the adult male was 22 feet 6 inches and in the adult female 23 feet 4 inches but that it varies very much. The extremes in the male being 31 feet 10 inches and 15 feet 6 inches. He states that in the adult the length of the bowel is independent of age, height and weight. End footnote and gradually diminishes in size from its commencement to its termination. It is contained in the central and lower part of the abdominal cavity and is surrounded above and at the sides by the large intestine. A portion of it extends below the superior aperture of the pelvis and lies in front of the rectum. It is in relation in front with the greater omentum and abdominal parieties and is connected to the vertebral column by a fold of peritoneum the misantary. The small intestine is divisible into three portions the duodenum, the jejunum and the ileum. The duodenum has received its name from being about equal in length to the breadth of 12 fingers 25 centimeters. It is the shortest, the widest and the most fixed part of the small intestine and has no misantary being only partially covered by peritoneum. Its course presents a remarkable curve somewhat of the shape of an imperfect circle so that its termination is not far removed from its starting point. In the adult the course of the duodenum is as follows Commencing at the pylorus it passes backward, upward and to the right beneath the quadrate lobe of the liver to the neck of the gallbladder varying slightly in direction according to the degree of distention of the stomach. It then takes a sharp curve and descends along the right margin of the head of the pancreas for a variable distance generally to the level of the upper border of the body of the fourth lumbar vertebra. It now takes a second bend and passes from right to left across the vertebral column having a slight inclination upward and on the left side of the vertebral column it ascends for about 2.5 cm and then ends opposite the second lumbar vertebra in the jejunum. As it unites with the jejunum it turns abruptly forward forming the duodenu-jejunal flexure. From the above description you'll be seen that the duodenum may be divided into four portions superior, descending, horizontal and ascending. Relations The superior portion Par's superior, first portion is about 5 cm long. Beginning at the pylorus it ends at the neck of the gallbladder. It is the most movable of the four portions. It is almost completely covered by perotoneum but a small part of its posterior surface near the neck of the gallbladder and the inferior vena cava is uncovered. The upper border of its first half has the hiparoduodenal ligament attached to it while to the lower border of the same segment the greater omentum is connected. It is in such close relation with the gallbladder that it is usually found to be stained by bile after death especially on its anterior surface. It is in relation above and in front with the quadrate lobe of the liver and the gallbladder behind with the gastroduodenal artery the common bile duct the cordal vein and below and behind with the head and neck of the pancreas. The descending portion par's descendants second portion is from 7 to 10 cm long and extends from the neck of the gallbladder on a level with the first lumbar vertebra along the right side of the vertebral column as low as the upper border of the body of the fourth lumbar vertebra. It is crossed in its middle third by the transverse colon the posterior surface of which is uncovered by peritoneum and is connected to the duodenum by a small quantity of connective tissue. The supra and infracolic portions are covered in front by peritoneum the infracolic part by the right leaf of the mesentery. Posteriorly the descending portion of the duodenum is not covered by peritoneum. The descending portion is in relation in front from above downward with the duodenal impression on the right lobe of the liver the transverse colon and the small intestine. Behind it has a variable relation to the front of the right kidney in the neighborhood of the hilium and is connected to it by loose areolar tissue. The renal vessels the inferior vena cava and the psoas below are also behind it. At its medial side is the head of the pancreas and the common bile duct. To its lateral side is the right colic flexured. The common bile duct and the pancreatic duct together perforate the medial side of this portion of the intestine obliquely some 7-10 cm below the pylorus. The accessory pancreatic duct sometimes pierces it about 2 cm above and slightly in front of these. The horizontal portion pars horizontalis third or preaortic or transverse portion is from 5-7.5 cm long. It begins at the right side of the upper border of the fourth lumbar vertebra and passes from right to left with a slight inclination upward in front of the great vessels and crura of the diaphragm and ends in the ascending portion in front of the abdominal aorta. It is crossed by the superior mesenteric vessels and the mesentery. Its front surface is covered by peritoneum except near the middle line where it is crossed by the superior mesenteric vessels. Its posterior surface is uncovered by peritoneum except towards its left extremity where the posterior layer of the mesentery may sometimes be found covering it to a variable extent. This surface rests upon the right cross of the diaphragm the inferior vena cava and the aorta. The upper surface is in relation with the head of the pancreas. The ascending portion of the duodenum is about 2.5 cm long. It ascends on the left side of the aorta as far as the level of the upper border of the second lumbar vertebra where it turns abruptly forward to become the duodenum forming the duodenum-duedunal flexure. It lies in front of the left psoas major and left renal vessels and is covered in front and partly at the sides by peritoneum continuous with the left portion of the mesentery. The superior part of the duodenum as stated above is somewhat movable but the rest is practically fixed and is bound down to neighboring viscera and the posterior abdominal wall by the peritoneum. In addition to this, the ascending part of the duodenum and the duodenum-duedunal flexure are fixed by a structure to which the name of musculosuspensorius duodenii has been given. This structure commences in the connective tissue from the celiac artery and left cross of the diaphragm and passes downward to be inserted into the superior border of the duodenum-duedunal curve and a part of the ascending duodenum and from this it is continued into the mesentery. It possesses, according to trites, plain muscular fibers mixed with the fibrous tissue of which it is principally made up. It is of little importance as a muscle but acts as a suspensory ligament. Vessels and nerves The arteries supplying the duodenum are the right gastric and superior pancreatic duodenal branches of the hepatic and the inferior pancreatic duodenal branch of the superior mesenteric. The veins end in the lienal and superior mesenteric. The nerves are derived from the celiac plexus. Jijunum and ileum The remainder of the small intestine from the end of the duodenum is named jijunum and ileum. The former term being given to the upper two fifths and the latter to the lower three fifths. There is no morphological line of distinction between the two and the division is arbitrary. But at the same time the character of the intestine gradually undergoes a change from the commencement of the jijunum to the end of the ileum so that a portion of the bowel taken from these two situations would present characteristic and market differences. The jijunum in testinum jijunum is wider its diameter being about 4 cm and is thicker, more vascular and of a deeper color than the ileum so that a given length weighs more. The circular folds, valvelly conventes of its mucous membrane are large and thickly set and its villi are larger than in the ileum. The aggregated lymph nodules are almost absent in the lower part of the jijunum and in the lower part are less frequently found than in the ileum and are smaller and tend to assume a circular form. By grasping the jijunum between the finger and thumb the circular folds can be felt through the walls of the gut these being absent in the lower part of the ileum. It is possible in this way to distinguish the upper from the lower part of the small intestine. The ileum, in testinum ileum is narrow its diameter being 3.75 cm and its coats thinner and less vascular than those of the jijunum. It possesses but few circular folds and they are small and disappear entirely towards lower end but aggregated lymph nodules, pares patches are larger and more numerous. The jijunum for the most part occupies the umbilical and left ileum regions while the ileum occupies chiefly the umbilical, hypogastric, and pelvic regions. The terminal part of the ileum usually lies in the pelvis from which it ascends over the right source and right ileac vessels. It ends in the right ileac fossa by opening into the medial side of the commencement of the large intestine. The jijunum and ileum are attached to the posterior abdominal wall by an extensive fold of peritoneum, the mesentary which allows the freest motion so that each coil can accommodate itself to changes in form and position. The mesentary is fan shaped. It's posterior border or root about 15 cm long is attached to the posterior abdominal wall from the left side of the body of the second lumbar vertebra to the right sacroileac articulation crossing successively the horizontal part of the duodenum, the aorta, the inferior vena cava, the ureter, and the right psoas muscle. Its breadth between its vertebral and intestinal borders averages about 20 cm and is greater in the middle than at its upper and lower ends. According to Lockwood it tends to increase in breadth as age advances. Between the two layers of which it is composed are contained blood vessels, nerves, lacteals, and lymph glands together with a variable amount of fat. Meckles diverticulum diverticulum ileae This consists of a pouch which projects from the lower part of the ileum in about 2% of subjects. Its average position is about one meter above the colic valve and its average length about 5 cm. Its caliber is generally similar to that of the ileum and its blind extremity may be free or may be connected with the abdominal wall or some other portion of the intestine by a fibrous band. It represents the remains of the proximal part of the vitiline duct, the duct of communication between the yolk sac and the primitive digestive tube in early fetal life. End of Section 19 Recording by Mark Rocher Section 20 of Grey's Anatomy Part 5 This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer please visit LibriVox.org Recording by Mark Rocher 2G The Small Intestine Structure The wall of the small intestine is composed of four coats seris, muscular, areolar and mucus. The seris coat Tunica serosa is derived from the peritoneum. The superior portion of the duodenum is almost completely surrounded by this membrane near its pyloric end but is only covered in front and at the other extremity. The descending portion is covered by it in front except where it is carried off by the transverse colon. And the inferior portion lies behind the peritoneum which passes over it without being closely incorporated with the other coats of this part of the intestine and is separated from it in and near the middle line by the superior mesenteric vessels. The rest of the small intestine is surrounded by the peritoneum excepting along its attached or mesenteric border here a space is left for the vessels and nerves to pass to the gut. The muscular coat Tunica muscularis consists of two layers of unstriped fibers an external longitudinal and an internal circular layer. The longitudinal fibers are thinly scattered over the surface of the intestine and are more distinct along its free border. The circular fibers form a thick uniform layer and are composed of plain muscle cells of considerable length. The muscular coat is thicker than at the lower part of the small intestine. The areolar or submucous coat Tela submucosa connects together the mucous and muscular layers. It consists of loose filamentous areolar tissue containing blood vessels, lymphatics and nerves. It is the strongest layer of the intestine. The mucous membrane Tunica mucosa is thick and highly vascular at the upper part of the small intestine but somewhat paler and thinner below. It consists of the following structures. Next the areolar or submucous coat is a double layer of unstriped muscular fibers outer longitudinal and inner circular. The muscularis mucosi internal to this is a quantity of retiform tissue enclosing in its meshes lymph corpuscles and in this the blood vessels and nerves ramify. Lastly a basement membrane supporting a single layer of epithelial cells which throughout the intestine are columnar in character. The cells are granular in appearance and each possesses a clear oval nucleus. At their superficial or unattached ends they present a distinct layer of highly refracting material in its vertical stri the striated border. The mucous membrane presents for examination the following structures contained within it or belonging to it. Circular folds villi intestinal glands duodenal glands solitary lymphatic nodules aggregated lymphatic nodules the circular folds plique circularies care cringy valves of care cring are large valvular flaps projecting into the lumen of the bowel they are composed of reduplications of the mucous membrane the two layers of the fold being bound together by sub mucous tissue unlike the folds in the stomach they are permanent and are not obliterated when the intestine is distended. The majority extend transversely around the cylinder of the intestine for about one half or two thirds of its circumference but some form complete circles and others have a spiral direction the latter usually extend a little more than once around the bowel but occasionally two or three times the larger folds are about eight millimeters in depth at their broadest part but the greater number are of smaller size the larger and smaller folds alternate with each other they are not found at the commencement of the duodenum but begin to appear about two point five or five centimeters beyond the pylorus in the lower part of the descending portion below the point where the bile and pancreatic ducts enter the intestine they are very large and closely approximated in the horizontal and descending portions of the duodenum and upper half of the jejunum they are large and numerous but from this point down to the middle of the ilium they diminish considerably in the lower part of the ilium they almost entirely disappear hence the comparative thinness of this portion of the intestine as compared with the duodenum and jejunum the circular folds retard the passage of the food along the intestines and afford an increased surface for absorption the intestinal villi are highly vascular processes projecting from the mucus membrane of the small intestine and giving to its surface of velvety appearance they are largest and most numerous in the duodenum and jejunum and become fewer and smaller in the ilium structure of the villi the essential parts of a villus are the lactyle vessel the blood vessels the epithelium the basement membrane and the muscular tissue of the mucosa all being supported and held together to form lymphoid tissue the lactyles are in some cases double and in some animals multiple but usually there is a single vessel situated in the axis of the villus each commences by dilated secal extremities near to but not quite at the summit of the villus the walls are composed of a single layer of endothelial cells the muscular fibres are derived from the muscularis mucosi they are arranged in longitudinal bundles around the lactyle vessel extending from the base to the summit of the villus and giving off laterally individual muscle cells which are enclosed by the reticulum and by it are attached to the basement membrane and to the lactyle the blood vessels form a plexus under the basement membrane and are enclosed in the reticular tissue these structures are surrounded by the basement membrane which is made up of a stratum of endothelial cells and upon this is placed a layer of columnar epithelium the characteristics of which have been described the retiform tissue forms a network in the meshes of which a number of leukocytes are found the intestinal glands glandular intestinales libercunae, crypts of libercun are found in considerable numbers over every part of the mucous membrane of the small intestine they consist of minut tubular depressions of the mucous membrane arranged perpendicularly to the surface upon which they open by small circular apertures they may be seen with the aid of a lens their orifices appearing as minut dots scattered between the villi their walls are thin consisting of a basement membrane lined by columnar epithelium and covered on their exterior by capillary vessels the duodenal glands glandular duodenales brunerae bruner's glands are limited to the duodenum and are found in the sub mucous areolar tissue they are largest and most numerous near the pylorus forming an almost complete layer in the superior portion and upper half of the descending portions of the duodenum they then begin to diminish in number and practically disappear at the junction of the duodenum and jejunum they are small compound assinotubular glands consisting of a number of alveoli lined by short columnar epithelium and opening by a single duct on the inner surface of the intestine the solitary lymphatic nodules noduli lymphatici solitary eye solitary glands are found scattered throughout the mucous membrane of the small intestine but are most numerous in the lower part of the ilium their free surfaces are covered with rudimentary villi except at the summits and each gland is surrounded by the openings of the intestinal glands each consists of a dense interlacing retiform tissue closely packed with lymph corpuscles and permeated with an abundant capillary network the interspaces of the retiform tissue are continuous with larger lymph spaces which surround the gland through which they communicate with the lactial system they are situated partly in the submucous tissue partly in the mucous membrane where they form slight projections of its epithelial layer the aggregated lymphatic nodules noduli lymphatici aggregata payers patches payers glands agmonated follicles tonsillae intestinales form circular or oval patches from 20 to 30 in number and varying in length from 2 to 10 cm the largest and most numerous in the ileum in the lower part of the jejunum they are small, circular and few in number they are occasionally seen in the duodenum they are placed lengthwise in the intestine and are situated in the portion of the tube most distant from the attachment of the mesentery each patch is formed of a group of solitary lymphatic nodules covered with mucous membrane but the patches do not as a rule possess villae on their free surfaces they are best marked in the young subject become indistinct in middle age and sometimes disappear altogether in advanced life they are freely supplied with blood vessels which form an abundant plexus around each follicle and give off fine branches permeating the lymphoid tissue in the interior of the follicle the lymphatic plexuses are especially abundant around these patches vessels and nerves the jejunum and ileum are supplied by the superior mesentery artery the intestinal branches of which having reached the attached borders of the bowel run between the serous and muscular coats with frequent inosculations to the free border where they also anastomose with other branches running around the opposite surface of the gut from these vessels numerous branches are given off which pierce the muscular coat supplying it and forming an intricate plexus in the submucous tissue from this plexus minute vessels passed the glands and villae of the mucous membrane the veins have a similar course and arrangement to the arteries the lymphatics of the small intestine lacteals are arranged in two sets those of the mucous membrane and those of the muscular coat the lymphatics of the villae commence in these structures in the manner described above they form an intricate plexus in the mucous and submucous tissue being joined by the lymphatics from the lymph spaces at the bases of the solitary nodules and from this pass to larger vessels at the mesenteric border of the gut the lymphatics of the muscular coat are situated to a great extent between the two layers of muscular fibers where they form a close plexus throughout their course they communicate freely with the lymphatics from the mucous membrane and empty themselves in the same manner as these into the origins of the lacteal vessels at the attached border of the gut the nerves of the small intestine are derived from the plexuses of sympathetic nerves around the superior mesenteric artery from this source they run to the myenteric plexus ourbox plexus of nerves and ganglia situated between the circular muscles from which the nervous branches are distributed to the muscular coats of the intestine from this a secondary plexus the plexus of the submucosa mysnerus plexus is derived and is formed by branches which have perforated the circular muscular fibers this plexus lies in the submucous coat of the intestine it also contains ganglia from which nerve fibers pass to the muscularis mucosi the nerve bundles of the submucous plexus are finer than those of the myenteric plexus end of section 20 recording by Mark Roche Tokyo Japan section 21 of Graves Anatomy part 5 this is a LibriVox recording all LibriVox recordings are in the public domain for more information or to volunteer, please visit LibriVox.org recording by Mark Roche Anatomy of the Human Body part 5 by Henry Gray chapter 2h the Large Intestine Intestinum Crassum the Large Intestine extends from the end of the ileum to the anus it is about 1.5 meters long being one fifth of the whole extent of the intestinal canal its caliber is largest at its commencement at the cecum and gradually diminishes as far as the rectum where there is a dilation of considerable size just above the anal canal it differs from the small intestine in its greater caliber its more fixed position its seculated form and in possessing certain appendages to its external coat the appendices epiploisi further, its longitudinal muscular fibers do not form a continuous layer around the gut in three longitudinal bands or tinii the Large Intestine in its course describes an arch which surrounds the convolutions of the small intestine it commences in the right ileiac region in a dilated part the cecum it ascends through the right lumbar and hypochondriac regions to the under surface of the liver it here takes a bend the right colic flexure to the left and passes transversely across the abdomen on the confines of the epigastric and umbilical regions to the left hypochondriac region it then bends again the left colic flexure and descends through the left lumbar and ileiac regions to the pelvis where it forms a bend called the sigmoid flexure from this it is continued along the posterior wall of the pelvis to the anus the Large Intestine is divided into the cecum colon, rectum and anal canal the cecum intestinum cecum the commencement of the Large Intestine is the large blind pouch situated below the colic valve its blind end is directed downward and its open end upward communicating directly with the colon of which this blind pouch appears to be the beginning or head and hence the old name of caplet cecum coli was applied to it its size is variously estimated by different authors but on an average it may be said to be 6.25 cm in length and 7.5 in breadth it is situated in the right ileiac fossa above the lateral half of the inguinal ligament it rests on the ileacus and psoas major and usually lies in contact with the anterior abdominal wall but the greater omentum and if the cecum be empty the peritoneal cells of small intestine may lie in front of it as a rule it is entirely enveloped by peritoneum but in a certain number of cases 5% bury the peritoneal covering is not complete so that the upper part of the posterior surface is uncovered and connected to the ileac fassia by connective tissue the cecum lies quite free in the abdominal cavity and enjoys a considerable amount of movement and it may become herniated down the right inguinal canal and has occasionally been found in an inguinal hernia on the left side the cecum varies in shape but according to trees in man it may be classified under one of four types in early fetal life it is short, conical and broad at the base with its apex turned upward and medial word toward the ileocolic junction it then resembles the cecum of some monkeys mangabe monkey as the fetus grows the cecum increases in length more than in breadth so that it forms a longer tube than in the primitive form and without the broad base but with the same inclination of the apex toward the ileocolic junction this form is seen in other monkeys e.g. the spider monkey as development goes on the lower part of the tube ceases to grow greatly increased so that at birth there is a narrow tube the vermaform process hanging from a conical projection the cecum this is the infantile form and as it persists throughout life in about 2% of cases it is regarded by trees as the first of his four types of human ceca the cecum is conical and the appendix rises from its apex the three longitudinal bands and are equidistant from each other in the second type the conical cecum has become quadrate by the growing out of a saccule on either side of the anterior longitudinal band these saccules are of equal size and the appendix arises from between them instead of from the apex of a cone this type is found in about 3% of cases the third type is the normal type of man here the two saccules the first type or uniform have grown at unequal rates the right with greater rapidity than the left in consequence of this and apparently new apex has been formed by the growing downward of the right saccule and the original apex with the appendix attached is pushed over to the left toward the iliocolic junction the three longitudinal bands still start from the base of the vermaform process but they are now no longer equidistant from each other the right saccule has grown between the anterior and posterior lateral bands pushing them over to the left this type occurs in about 90% of cases the fourth type is merely an exaggerated condition of the third the right saccule is still larger and at the same time the left saccule has become atrophied so that the original apex of the cecum with the vermaform process is close to the iliocolic junction versus medial word to the same situation this type is present in about 4% of cases the vermaform process or appendix processes vermaformis is a long narrow worm shaped tube which starts from what was originally the apex of the cecum and may pass in one of several directions upward behind the cecum to the left behind the ilium and mesentery is lowered into the lesser pelvis it varies from 2 to 20 cm in length its average being about 8.3 cm it is retained in position by a fold of peritoneum mesentereal derived from the left leaf of the mesentery this fold in the majority of cases is more or less triangular in shape and as a rule extends along the entire length of the tube between its two layers and close to its free margin lies the appendicular artery the canal of the vermaform process is small extends through the whole length of the tube and communicates with the cecum by an orifice which is placed below and behind the iliocecal opening it is sometimes guarded by a semi-lunar valve formed by a fold of mucous membrane but this is by no means constant structure the coats of the vermaform process are the same as those of the intestine serous, muscular submucous and mucous the serous coat forms a complete investment for the tube except along the narrow line of attachment of its mesentereal in its proximal two thirds the longitudinal muscular fibers do not form three bands as in the greater part of the large intestine but invest the whole organ except at one or two points where both the longitudinal and circular fibers are deficient so that the peritoneal and submucous coats are contiguous over small areas the circular muscle fibers form a much thicker layer than the longitudinal fibers and are separated from them by a small amount of connective tissue the submucous coat is well marked and contains a large number of masses of lymphoid tissue which cause the mucous membrane to bulge into the lumen and so render the latter of small size in a regular shape the mucous membrane is lined by columnar epithelium and resembles that of the rest of the large intestine but the intestinal glands are fewer in number the colic valve valvula coli iliocecal valve the lower end of the ilium ends by opening into the medial and back part of the large intestine at the point of junction of the cecum with the colon is guarded by a valve consisting of two segments or lips which project into the lumen of the large intestine if the intestine has been inflated and dried the lips are of semilunar shape the upper one nearly horizontal in direction is attached by its convex border to the line of junction of the ilium with the colon the lower lip which is longer and more concave is attached to the line of junction at the ends of the aperture the two segments of the valve coalesce and are continued as narrow membranous ridges around the canal for a short distance forming the frenula of the valve the left or anterior end of the aperture is rounded the right or posterior is narrow and pointed in the fresh condition or in specimens which have been hardened in situ the lips project as thick cushion-like folds the lumen of the large cut while the opening between them may present the appearance of a slit or may be somewhat oval in shape each lip of the valve is formed by a reduplication of the mucous membrane and of the circular muscular fibers of the intestine the longitudinal fibers and peritoneum being continued uninterruptedly from the small to the large intestine the surfaces of the valve directed toward the ilium are covered with villi they present the characteristic structure of the mucous membrane of the small intestine while those turned toward the large intestine are destitute of villi and marked with the orifices of the numerous tubular glands peculiar to the mucous membrane of the large intestine these differences in structure continue as far as the free margins of the valve it is generally maintained that this valve prevents reflux from the cecum into the ilium but in all probability it acts as a sphincter around the end of the ilium and prevents the contents of the ilium from passing too quickly into the cecum the colon is divided into four parts the ascending, transverse descending and sigmoid the ascending colon colon ascendance is smaller in caliber than the cecum with which it is continuous it passes upward from its commencement at the cecum opposite the colic valve to the under surface of the right lobe of the liver on the right of the gallbladder where it is lodged in a shallow depression the colic impression here it bends abruptly forward and to the left forming the right colic hepatic flexure it is retained in contact with the posterior wall of the abdomen by the peritoneum which covers its anterior surface and sides its posterior surface being connected by loose areolar tissue with the iliacus quadratus lumborum aponeurotic origin of transversus abdominis and with the front of the lower and lateral part of the right kidney sometimes the peritoneum completely invests it and forms a distinct but narrow mesocolon it is in relation in front with the convolutions of the ilium and the abdominal parietes the transverse colon colon transversum the longest and most movable part of the colon passes with a downward convexity from the right hypochondriac region across the abdomen opposite the confines of the epigastric and umbilical zones into the left hypochondriac region where it curves sharply on itself beneath the lower end of the spleen forming the left colic splenic flexure in its course it describes an arch the concavity of which is directed backward and a little upward toward its splenic end the left u-shaped curve which may descend lower than the main curve it is almost completely invested by peritoneum and is connected to the inferior border of the pancreas by a large and wide duplicature of that membrane the transverse mesocolon it is in relation by its upper surface with the liver and gallbladder the greater curvature of the stomach and the lower end of the spleen by its anterior surface with the anterior layers of the greater abdominal parietes its posterior surface is in relation from right to left with the descending portion of the duodenum the head of the pancreas and some of the convolutions of the jejunum and ilium the left colic or splenic flexure is situated at the junction of the transverse and descending parts of the colon and is in relation with the lower end of the spleen and the tail of the pancreas the flexure is so acute that the transverse colon usually lies in contact with the front of the descending colon it lies at a higher level than and on a plane posterior to the right colic flexure and is attached to the diaphragm opposite the 10th and 11th ribs by a peritoneal fold named the frenicocolic ligament which assists in supporting the lower end of the spleen the descending colon colon descendants passes downward through the left hypochondriac and lumbar regions along the lateral border of the left kidney at the lower end of the kidney it turns medial word toward the lateral border of the psoas and then descends in the angle between psoas and quadratus lumborum to the crest of the ilium where it ends in the iliac colon the peritoneum covers its anterior surface and sides while its posterior surface is connected by areolar tissue with the lower and lateral part of the left kidney the aponeurotic origin of the transversus abdominis and the quadratus lumborum it is smaller in caliber and more deeply placed than the ascending colon and is more frequently covered with peritoneum on its posterior surface than the ascending colon treves in front of it are some coils of the small intestine the iliac colon is situated in the left iliac fossa 1 cm long it begins at the level of the iliac crest where it is continuous with the descending colon and ends in the sigmoid colon at the superior aperture of the lesser pelvis it curves downward and medial word in front of the iliacus and psoas and as a rule is covered by peritoneum on its sides and anterior surface only this is a LibriVox recording all LibriVox recordings are in the public domain for more information or to volunteer please visit LibriVox.org recording by Mark Rocher anatomy of the human body part 5 by Henry Gray chapter 2h the large intestine intestinum crassum the sigmoid colon colon sigmoideum pelvic colon sigmoid flexure forms a loop which averages about 40 cm in length and normally lies within the pelvis but on account of its freedom of movement is liable to be displaced into the abdominal cavity it begins at the superior aperture of the lesser pelvis where it is continuous with the iliac colon and passes transversely across the front of the sacrum to the right side of the pelvis it then curves on itself and turns toward the left to reach the middle line at the level of the third piece of the sacrum where it bends downward and ends in the rectum it is completely surrounded by peritoneum which forms a mesentery sigmoid mesocolon which diminishes in length from the center toward the ends of the loop where it disappears so that the loop is fixed at its junctions with the iliac colon and rectum there is a change of movement in its central portion behind the sigmoid colon are the external iliac vessels the left piriformis and left sacral plexus of nerves in front it is separated from the bladder in the male and the uterus in the female by some coils of the small intestine the rectum in testinum rectum is continuous above with the sigmoid colon while below it ends in the anal canal from its origin at the level of the third sacral vertebra it passes downward lying in the sacrocoxidial curve and extends for about 2.5 cm in front of and a little below the tip of the coccyx as far as the apex of the prostate it then bends sharply backward into the anal canal it therefore presents two anteroposterior curves and upper with its convexity backwards and the lower with its convexity forward two lateral curves are also described one to the right opposite the junction of the third and fourth sacral vertebra and the other to the left opposite the left sacrocoxidial articulation they are however of little importance the rectum is about 12 cm long and at its commencement its caliber is similar to that of the sigmoid colon but near its termination it is dilated to form the rectal ampulla the rectum has no sacculations comparable to those of the colon but when the lower part of the rectum is contracted its mucous membrane is thrown into a number of folds which are longitudinal in direction and are effaced by the distention of the gut besides these there are certain permanent transverse folds of a semi-lunar shape known as Houston's valves they are usually three in number sometimes a fourth is found and occasionally only two are present one is situated near the commencement of the rectum on the right side a second extends inward from the left side of the tube opposite the middle of the sacrum a third, the largest and most constant projects backward from the four part of the rectum opposite the fundus of the urinary bladder when a fourth is present it is situated nearly 2.5 cm above the anus on the left and posterior wall of the tube these folds are about 12 mm in width and contain some of the circular fibers of the gut in the empty state of the intestine they overlap each other as Houston remarks so as effectually as to require considerable maneuvering to conduct a bougie or the finger along the canal their use seems to be to support the weight of fecal matter and prevent its urging toward the anus where its presence always excites the sensation of demanding its discharge footnote Patterson the form of the rectum journal of anatomy and physiology volume 43 utilizes the third fold for the purpose of dividing the rectum into an upper and lower portion he considers the latter to be just as much a duct as the narrower anal canal below and maintains that under normal conditions it does not contain feces except during the act of defecation end footnote the peritoneum is related to the upper two thirds of the rectum covering at first its front and sides but lower down its front only from the latter it is reflected onto the seminal vesicles in the male and the posterior vaginal wall in the female the level at which the peritoneum leaves the anterior wall of the rectum to be reflected onto the viscous in front of it is of considerable importance from a surgical point of view in connection with the removal of the lower part of the rectum it is higher in the male than in the female in the former the height of the recto vesicle excavation is about 7.5 cm i.e. the height to which an ordinary index finger can reach from the anus in the female the height of the recto uterine excavation is about 5.5 cm from the anal orifice the rectum is surrounded by a dense tube the fascia derived from the fascia endopelvena but fused behind with the fascia covering the sacrum and coccyx the fascial tube is loosely attached to the rectal wall by areolar tissue in order to allow the distention of the viscous relations of the rectum the upper part of the rectum is in relation behind with the superior hemorrhidal vessels the left piriformis and left sacral plexus of nerves which separated from the pelvic surfaces of the sacral vertebra in its lower part it lies directly on the sacrum, coccyx and levatoris ani a dense fascia alone intervening in front it is separated above in the male from the fundus of the bladder in the female from the intestinal surface of the uterus and its appendages by some convolutions of the small intestine and frequently by the sigmoid colon below it is in relation in the male with the triangular portion of the fundus of the bladder the vesculi seminalis and ductus differentis and more anteriorly with the posterior surface of the prostate in the female with the posterior wall of the vagina the anal canal paris analis recti or terminal portion of the large intestine begins at the level of the apex of the prostate is directed downward and backward and ends at the anus it forms an angle with the lower part of the rectum and measures from 2.5 to 4 cm in length it has no peritoneal covering but is invested by the sphincter ani internus supported by the levatoris ani and surrounded at its termination by the sphincter ani externus in the empty condition it presents the appearance of an anterior posterior longitudinal slit behind it is a mass of muscular and fibrous tissue the anal coxigial body simington in front of it in the male but separated by connective tissue from it are the membranous portion and bulb of the urethra and the fascia of the urogenital diaphragm and in the female it is separated from the lower end of the vagina by a mass of muscular and fibrous tissue named the perinatal body the lumen of the anal canal presents in its upper half a number of vertical folds produced by an infolding of the mucous membrane and some of the muscular tissue they are known as the rectal columns morgani and are separated from one another by furrows rectal sinuses which end below in small valve-like folds termed anal valves which join together the lower ends of the rectal columns structure of the colon the large intestine has four coats serous, muscular areolar and mucous the serous coat tunica serosa is derived from the peritoneum and invests the different portions of the large intestine to a variable extent the cecum is completely covered by the serous membrane except in about 5% of cases where the upper part of the posterior surface is uncovered the ascending, descending and iliac parts of the colon are usually covered only in front and at the sides a variable amount of the posterior surface is uncovered the transverse colon is almost completely invested the parts corresponding to the attachment of the greater omentum and transverse mesocolon being alone accepted the sigmoid colon is entirely surrounded the rectum is covered above on its anterior surface and sides below on its anterior aspect only the anal canal is entirely devoid of any serous covering in the course of the colon the peritoneal coat is thrown into a number of small pouches filled with fat called appendices epiploysii they are most numerous on the transverse colon the muscular coat tunica muscularis consists of an external longitudinal and an internal circular layer of non-striped muscular fibers the longitudinal fibers do not form a continuous layer over the whole surface of the large intestine in the cecum and colon they are especially collected into three flat longitudinal bands tini coli each of about 12 millimeters in width one, the posterior is placed along the attached border of the intestine the anterior the largest corresponds along the arch of the colon to the attachment of the greater omentum but it's in front in the ascending, descending and iliac parts of the colon and in the sigmoid colon the third or lateral band is found on the medial side of the ascending and descending parts of the colon and on the under aspect of the transverse colon these bands are shorter than the other coats of the intestine and serve to produce the sacculi which are characteristic of the cecum and colon accordingly when they are dissected off the tube can be lengthened and its sacculated character disappears in the sigmoid colon the longitudinal fibers become more scattered and around the rectum they spread out and form a layer which completely encircles this portion of the gut but is thicker on the anterior and posterior surfaces where it forms two bands than on the lateral surfaces in addition two bands of plane muscular tissue arrives from the second and third coccidial vertebrae and pass downward and forward to blend with the longitudinal muscular fibers on the posterior wall of the anal canal these are known as the rectococcidial muscles the circular fibers form a thin layer over the cecum and colon being especially accumulated in the intervals between the sacculi in the rectum they form a thick layer and in the anal canal they become numerous and constitute the sphincter ani in Ternus the areolar coat Tela submucosa submucous coat connects the muscular and mucous layers closely together the mucous membrane tunica mucosa in the cecum and colon is pale smooth distitute of villi and raised into numerous crescentic folds which correspond to the intervals between the sacculi in the rectum it is thicker of a darker color more vascular and connected loosely to the muscular coat as in the esophagus as in the small intestine the mucous membrane consists of a muscular layer the muscularus mucosi a quantity of retiform tissue in which the vessels ramify a basement membrane and epithelium which is of the columnar variety and resembles the epithelium found in the small intestine the mucous membrane of the large intestine presents for examination glands and solitary lymphatic nodules the glands of the great intestine are minut tubular prolongations of the mucous membrane arranged perpendicularly side by side over its entire surface they are longer more numerous and placed in much closer opposition than those of the small intestine and they open by minut rounded orifices upon the surface of the prebreform appearance each gland is lined by short columnar epithelium and contains numerous goblet cells the solitary lymphatic nodules noduli lymphatic solitary eye of the large intestine are most abundant in the cecum and vermaform process but are irregularly scattered also over the rest of the intestine they are similar to those of the small intestine vessels and nerves the arteries supplying the colon are derived from the colic and sigmoid branches of the mesenteric arteries they give off large branches which ramify between and supply the muscular coats and after dividing into small vessels in the submucous tissue pass to the mucous membrane the rectum is supplied by the superior hemorrhoidal branch of the inferior mesenteric and the anal canal by the middle hemorrhoidal from the hypogastric and the inferior hemorrhoidal from the internal pudendal artery the superior hemorrhoidal the continuation of the inferior mesenteric divides into two branches which run down either side of the rectum to within about 12.5 cm of the anus they here split up into about six branches which pierce the muscular coat and descend between it and the mucous membrane in a longitudinal direction parallel with each other in the anus by internus where they anastomos with the other hemorrhoidal arteries and form a series of loops around the anus the veins of the rectum commence in a plexus of vessels which surrounds the anal canal in the vessels forming this plexus are smaller secular dilations just within the margin of the anus from the plexus about six vessels of considerable size are given off these ascend between the muscular plexus coats for about 12.5 cm running parallel to each other they then pierce the muscular coat and by their union form a single trunk the superior hemorrhoidal vein this arrangement is termed the hemorrhoidal plexus it communicates with the tributaries of the middle and inferior hemorrhoidal veins at it's commencement and thus a communication is established between the systemic and portal circulations the lymphatics of the large intestine are described on page 711 the nerves are derived from the sympathetic plexuses around the branches of the superior and inferior mesenteric arteries they are distributed in a similar way to those found in the small intestine congenital hernia there are some varieties of oblique inguinal hernia depending upon congenital defects in the saccus vaginalis the pouch of peritneum the testes normally this pouch is closed before birth closure commencing at two points vis at the abdominal inguinal ring and at the top of the epididymis and gradually extending until the whole of the intervening portion is converted into a fibrous cord from failure in the completion of this process variations in the relation of the hernia protrusion to the testes and tunica vaginalis are produced these constitute distinct varieties of inguinal hernia vis the hernia of the funicular process and the complete congenital variety where the saccus vaginalis remains patterned throughout the cavity of the tunica vaginalis communicates directly with that of the peritneum the intestine descends along this pouch into the cavity of the tunica vaginalis which constitutes the sac of the hernia and the gut lies in contact with the testes though this form of hernia is termed complete congenital the term does not imply that the hernia existed at birth but merely that a condition is present which may allow the descent of the hernia at any moment as a matter of fact congenital hernia frequently do not appear until adult life where the processes vaginalis is occluded at the lower point only i.e. just above the testes the intestine descends into the pouch of the peritneum as far as the testes but is prevented from entering the sac of the tunica vaginalis by the septum which has formed between it and the pouch this is known as hernia into the funicular process or incomplete congenital hernia it differs from the former in that instead of enveloping the testes it lies above it End of Section 22 Recording by Mark Roche Tokyo, Japan Section 23 of Anatomy of the Human Body, Part 5 This is a LibriVox recording All LibriVox recordings are in the public domain for more information or to volunteer please visit LibriVox.org Anatomy of the Human Body, Part 5 by Henry Gray The liver Part 1, HEPAR The liver the largest gland in the body has both external and internal secretions formed in the hepatic cells Its external secretion, the bile is collected after passing through the bile capillaries by the bile ducts which join like the twigs and branches of a tree to form two large ducts which unite to form the hepatic duct The bile is either carried to the gallbladder by the cystic duct or poured directly into the duodenum by the common bile duct where it aids in digestion The internal secretions are concerned with the metabolism of both nitrogenous and carbohydrate materials absorbed from the intestine and carried to the liver by the portal vein The carbohydrates are stored in the hepatic cells in the form of glycogen which is secreted in the form of sugar directly into the bloodstream Some of the cells lining the blood capillaries of the liver are concerned in the destruction of red blood corpuscles It is situated in the upper and right parts of the abdominal cavity occupying almost the whole of the right hypochondrium in the upper part of the epigastrium and not uncommonly extending into the left hypochondrium as far as the mammillary line In the male it weighs from 1.4 to 1.6 kilograms in the female from 1.2 to 1.4 kilograms It is relatively much larger in the fetus than in the adult constituting in the former about 1.18 and in the latter about 1.36 of the entire body weight Its greatest transverse measurement is from 10 to 22.5 centimeters Vertically, near its lateral or right surface, it measures about 15 to 17.5 centimeters While its greatest antero-posterior diameter is on a level with the upper end of the right kidney and is from 10 to 12.5 centimeters Opposite the vertebral column its measurement from before backward is reduced to about 7.5 centimeters Its consistency is that of a soft solid It is friable, easily lacerated and highly vascular Its color is a dark reddish brown and its specific gravity is 1.05 To obtain a correct idea of its shape it must be hardened in situ and it will then be seen to present the appearance of a wedge the base of which is directed to the right and the thin edge toward the left Simmington describes its shape as that of a right-angle triangular prism with the right angle rounded off Surfaces The liver possesses three surfaces namely superior, inferior and posterior A sharp, well-defined margin divides the inferior from the superior in front The other margins are rounded The superior surface is attached to the diaphragm an anterior abdominal wall by a triangular falcon fold of peritoneum the falcon ligament in the free margin of which is a rounded cord, the ligamentum terris obliterated umbilical vein The line of attachment of the falcon ligament divides the liver into two parts termed the right and left lobes the right being much the larger The inferior and posterior surfaces are divided into four lobes by five fossey which are arranged in the form of the letter H The left limb of the H marks on these surfaces the division of the liver into right and left lobes It is known as the left sagittal fossa and consists of two parts namely the fossa for the umbilical vein in front and the fossa for the ductus venosis behind The right limb of the H is formed in front by the fossa for the gallbladder and behind by the fossa for the inferior vena cava These two fossey are separated from one another by a band of liver substance termed the caudate process The bar connecting the two limbs of the H is the porta, transverse fissure In front of it is the quadrate lobe behind it the caudate lobe The superior surface vasy superior comprises a part of both lobes and as a whole is convex and fits under the vault of the diaphragm which in front separates it on the right from the sixth to the tenth ribs in their cartilages and on the left from the seventh and eighth costal cartilages Its middle part lies behind the xyfoid process and in the angle between a diverging rib cartilage of opposite sides is in contact with the abdominal wall Behind this the diaphragm separates the liver from the lower part of the lungs and plury, the heart and pericardium and the right costal arches from the seventh to the eleventh inclusive. It is completely covered by peritoneum except along the line of attachment of the falsiform ligament The inferior surface Fassey's inferior visceral surface is uneven concave directed downward backward into the left and is in relation with the stomach and duodenum, the right colic flexure and the right kidney and suprarenal gland The surface is almost completely invested by peritoneum. The only parts devoid of this covering are where the gallbladder is attached to the liver and at the portahepatus where the two layers of the lesser momentum are separated from each other by the blood vessels and ducts of the liver The inferior surface of the left lobe presents behind the left the gastric impression molded over the anterior superior surface of the stomach and to the right of this a rounded eminence the tuberomentale which fits into the concavity of the lesser curvature of the stomach and lies in front of the anterior layer of the lesser momentum. The under surface of the right lobe is divided into two unequal portions by the fossa for the gallbladder. The portion to the left, the smaller of the two is the quadrate lobe and is in relation with the pyloric end of the stomach, the superior portion of the duodenum and the transverse colon. The portion of the under surface of the right lobe to the right of the fossa for the gallbladder presents two impressions, one situated behind the other and separated by a ridge. The anterior of these two impressions, the colic impression is shallow and is produced by the right colic flexure. The posterior, the renal impression is deeper and is occupied by the upper part of the right kidney and the lower part of the right super renal gland. Medial to the renal impression is a third and slightly marked impression, lying between it and the neck of the gallbladder. This is caused by the descending portion of the duodenum and is known as the duodenal impression. Just in front of the inferior vena cava is a narrow strip of liver tissue, the codate process which connects the right inferior angle of the codate lobe to the upper surface of the right lobe. It forms the upper boundary of the epiploic foramen of the peritoneum. The posterior surface, feces posterior, is rounded and broad behind the right lobe but narrow on the left. Over a large part of its extent, it is not covered by peritoneum. This uncovered portion is about 7.5 cm broad at its widest part and is in direct contact with the diaphragm. It is marked off from the upper surface by the line of reflection of the upper layer of the coronary ligament and from the under surface by the line of reflection of the lower layer of the coronary ligament. The central part of the posterior surface presents a deep concavity which is molded on the vertebral column and crura of the diaphragm. To the right of this, the inferior vena cava is lodged in its fossa between the uncovered area and the codate lobe. Close to the right of this fossa and immediately above the renal impression is a small, triangular, depressed area, the supra renal impression the greater part of which is the void of peritoneum. It lodges the right supra renal gland. To the left of the inferior vena cava is the codate lobe which lies between the fossa for the vena cava and the fossa for the ductus venosis. Its lower end projects and forms part of the posterior border of the porta. On the right it is connected with the under surface of the right lobe of the liver by the codate process and on the left it presents an elevation the papillary process. Its posterior surface rests upon the diaphragm being separated from it merely by the upper part of the elemental bursa. To the left of the fossa for the ductus venosis is a groove in which lies the antrum cardiacum of the esophagus. The anterior border, margo anterior is thin and sharp and marked opposite the attachment and also form ligament by a deep notch the umbilical notch and opposite the cartilage of the ninth rib by a second notch for the fundus of the gallbladder. In adult males this border generally corresponds with the lower margin of the thorax in the right mammillary line but in women and children it usually projects below the ribs. The left extremity of the liver is thin and flattened from above downward. Fosse The left sagittal fossa sagittalis sinistra longitudinal fissure is a deep groove which extends from the notch on the anterior margin of the liver to the upper border of the posterior surface of the organ. It separates the right and left lobes. The porta joins it at right angles and divides it into two parts. The anterior part or fossa for the umbilical vein lodges the umbilical vein in the fetus and its remains the ligamentum terrace in the adult. It lies between the quadrate lobe and the left lobe of the liver and is partially bridged over by a prolongation of the hepatic substance the pawn's hepatus. The posterior part or fossa for the ductus venosis lies between the left lobe and the quadrate lobe. It lodges in the fetus, the ductus venosis and in the adult a slender fibrous cord the ligamentum venosum the obliterated remains of that vessel. The porta or transverse fissure porta hepatus is a short but deep fissure about 5 cm long extending transversely across the under surface of the left portion of the right lobe nearer its posterior surface than its anterior border. It joins nearly at right angles with the left sagittal fossa and separates the quadrate lobe in front from the corite lobe in process behind. It transmits the portal vein the hepatic artery and nerves and the hepatic duct and lymphatics. The hepatic duct lies in front and to the right the hepatic artery to the left and the portal vein behind and between the duct and artery. The fossa for the gallbladder fossa vesike fellae is a shallow oblong fossa placed on the under surface of the right lobe parallel with the left sagittal fossa it extends from the anterior free margin of the liver which is notched by it to the right extremity of the porta. The fossa for the inferior vena cava fossa vena cavi is a short deep depression occasionally a complete canal in consequence of the substance of the liver surrounding the vena cava. It extends obliquely upward on the posterior surface between the codate lobe and the bare area of the liver and is separated from the porta by the codate process. On slitting open the inferior vena cava the orifices of the hepatic veins will be seen opening into this vessel at it's upper part after perforating the floor of this fossa. Lobes. The right lobe lobe is hepatis dexter is much larger than the left the proportion between them being as 6 to 1. It occupies the right hypochondrium and is separated from the left lobe on it's upper surface by the falsiform ligament on it's under and posterior surfaces by the left sagittal fossa and in front by the umbilical notch. It is of a somewhat quadrilateral form it's under and posterior surfaces being marked by 3 fossa the porta and the fossa for the gallbladder and inferior vena cava which separate it's left part into 2 smaller lobes the quadrate and codate lobes The impressions on the right lobe have already been described the quadrate lobe lobes quadratus is situated on the under surface of the right lobe bounded in front by the anterior margin of the liver behind by the porta on the right by the fossa for the gallbladder and on the left by the fossa for the umbilical vein it is oblong in shape it's anterior posterior diameter being greater than it's transverse the codate lobe lobes codatus spigilion lobe is situated upon the posterior surface of the right lobe of the liver in 11th thoracic vertebrae it is bounded below by the porta on the right by the fossa for the inferior vena cava and on the left by the fossa for the ductus venosis it looks backward being nearly vertical in position it is longer from above downward than from side to side and is somewhat concave in the transverse direction the codate process is a small elevation of the hepatic substance extending obliquely lateral word from the upper extremity of the codate lobe to the under surface of the right lobe it is situated behind the porta and separates the fossa for the gallbladder from the commencement of the fossa for the inferior vena cava the left lobe lobes hepata sinister is smaller and more flattened than the right it is situated in the epigastric and left hypochondriac regions its upper surface is slightly convex and is molded onto the diaphragm its under surface presents the gastric impression and omental tuberosity already referred to ligaments the liver is connected to the under surface of the diaphragm and to the anterior wall of the abdomen by five ligaments four of these, the fossa form the coronary and the tulateral are peritoneal folds the fifth, the round ligament is a fibrous cord the obliterated umbilical vein the liver is also attached to the lower curvature of the stomach by the hepato gastric and to the duodenum by the hepato duodenal ligament the fossa form ligament ligamentum fossa formi hepatis is a broad and thin anterior peritoneal fold fossa form in shape its base being directed downward and backward its apex upward and backward it is situated in an antero posterior plane but lies obliquely so that one surface faces forward and is in contact with the peritoneum behind the right rectus and the diaphragm while the other is directed backward and is in contact with the left lobe of the liver it is attached by its left margin to the under surface of the diaphragm and the posterior surface of the sheath of the right rectus as low down as the umbilicus by its right margin it extends from the notch on the anterior margin of the liver as far back as the posterior surface it is composed of two layers of peritoneum closely united together its base or free edge contains between its layers the round ligament and the par umbilical veins the coronary ligament ligamentum coronarium hepatis consists of an upper and a lower layer the upper layer is formed by the reflection of the peritoneum from the upper margin of the bare area of the liver to the under surface of the diaphragm it is continuous with the right layer of the phalliform ligament the lower layer is reflected from the lower margin of the bare area onto the right kidney and super renal gland and is termed the hepatorenal ligament the triangular ligaments lateral ligaments are two in number, right and left the right triangular ligament ligamentum triangulari dextrum is situated at the right extremity of the bare area and is a small fold which passes to the diaphragm being formed by the opposition of the upper and lower layers of the coronary ligament the left triangular ligament ligamentum triangulari sinistrum is a fold of some considerable size which connects the posterior part of the upper surface of the left lobe to the diaphragm its anterior layer is continuous with the left layer of the phalliform ligament the round ligament ligamentum terus hepatis is a fibrous cord resulting from the obliteration of the umbilical vein it ascends from the umbilicus in the free margin of the phalliform ligament to the umbilical notch of the liver from which it may be traced in its proper fossa on the inferior surface of the liver to the porta where it becomes continuous with the ligamentum venosum fixation of the liver several factors contribute to maintain the liver in place the attachments of the liver to the diaphragm and triangular ligaments and the intervening connective tissue of the uncovered area together with the intimate connection of the inferior vena cava by the connective tissue and hepatic veins would hold up the posterior part of the liver some support is derived from the pressure of the abdominal viscera which completely fill the abdomen whose muscular walls are always in a state of tonic contraction the superior surface of the liver is perfectly fitted to the under surface of the diaphragm so that atmospheric pressure alone would be enough to hold it against the diaphragm the latter in turn is held up by the negative pressure in the thorax the lax phalliform ligament certainly gives no support though it probably limits lateral displacement End of section 23