CHAPTER VIII.

ORGANOLOGY.—Continued.

=The Abdomen.=—The abdomen is the largest cavity in the body. It is oval in form, the extremities of the oval being directed upward and downward.

To facilitate description, the abdomen is artificially divided into two parts:

An upper and larger part, the abdomen proper.

A lower and smaller part, the pelvis.

These two cavities are not separated from each other, but the limit between them is a line drawn around the brim of the true pelvis.

The abdomen proper differs from the other great cavities of the body, in being bounded for the most part by muscles and fascia.

It varies in capacity and shape according to the condition of the viscera which it contains and in addition, it varies in form and extent with age and sex.

Boundaries.—The diaphragm forms the dome over the abdomen, the cavity of the abdomen extending high into the bony thorax.

The lower end of the abdomen is limited by the bones of the pelvis.

In front and at the sides it is bounded by the lower ribs and abdominal muscles.

Behind by the vertebral column and muscles.

Regions.—For convenience of description of the viscera, the abdomen is artificially divided into nine regions. Thus if two circular lines are drawn around the body, the one at the extremities of the ninth ribs where they join the costal cartilages, and the other around the crest of the ileum, the abdominal cavity is divided into three zones.

If two parallel lines are now drawn perpendicular upward from the center of Poupart's ligament, each of these zones is subdivided into three parts.

The middle region of the upper zone is called the epigastric; and the two lateral regions, the right and left hypochondriac. The central region of the middle zone is called the umbilical; and the two lateral regions, the right and left lumbar regions. The middle region of the lower zone is called the hypogastric; and the two lateral regions are called the right and the left inguinal regions.

The viscera contained in each of these are as follows:

Right Hypochondriac | Epigastric Region | Left Hypochondriac | | The greater part of | The greater part of | The fundus of the the right lobe of the | the stomach including | stomach, the spleen, liver, the hepatic | both cardiac and | the extremity of the flexure of the colon | pyloric orifices, the | pancreas, the splenic and part of the right | left lobe and part of | flexure of the colon kidney. | the right lobe of the | and part of the left | liver and the gall- | kidney and small | bladder, the | portion of the left | pancreas, the | lobe of the liver. | duodenum, the | | suprarenal capsules | | and parts of the | | kidneys. | ——————————————————————+———————————————————————+—————————————————————— Right Lumbar | Umbilical Region | Left Lumbar | | Ascending colon, part | The transverse colon, | Descending colon, of the right kidney | part of the great | part of the omentum, and some convolutions | omentum and | part of the left of the small | mesentery, transverse | kidney and some intestines. | part of the duodenum | convolutions of the | and some convolutions | small intestines. | of the jejunum and | | ileum and part of | | both kidneys. | ——————————————————————+———————————————————————+—————————————————————— Right Inguinal or | Hypogastric Region | Left Inguinal or Iliac | | Iliac | Convolutions of the | The caecum and | small intestines, the | Sigmoid flexure of vermiform appendix | bladder in children | the colon and a and a portion of the | and in adults if | portion of the ascending colon. | distended, and the | descending colon. | uterus during | | pregnancy. |

=The Stomach.=—The stomach is the principal organ of digestion. It is the most dilated part of the alimentary canal, and is situated between the termination of the esophagus and the commencement of the small intestines. It is placed in part immediately behind the anterior wall of the abdomen and beneath the diaphragm.

_The lesser curvature_ of the stomach extends between the cardiac and the pyloric orifices along the right border of the organ.

_The greater curvature_ of the stomach is directed to the left, and is four or five times as long as the lesser curvature.

_The cardia_ is the point at which the esophagus enters the stomach wall.

_The cardiac orifice_ is the opening by which the esophagus communicates with the stomach. It is sometimes called the esophageal opening. It is situated on a level with the body of the tenth and eleventh dorsal vertebrae. It is to the left of and in front of the aorta. On the anterior surface of the body the cardiac orifice corresponds to the articulation of the seventh left costal cartilage to the sternum.

_The pylorus_ is the point at which the stomach passes into the duodenum.

_The pyloric orifice_ is the opening by means of which the stomach communicates with the duodenum.

This orifice is guarded by the _pyloric valve_. When the stomach is empty the pylorus is situated just to the right of the median line of the body on a level with the upper border of the first lumbar vertebra. On the anterior surface of the body its position would be indicated by a point one inch below the tip of the ensiform process and a little to the right.

The size of the stomach varies considerable in different subjects. The distance between the two orifices is from three to six inches. The weight of the stomach is about four and one-half ounces.

The capacity of the adult male stomach is from five to eight pints. The stomach of a new born child holds about one ounce.

The stomach is held in place by the attachment of the esophagus to the diaphragm and the fixation of the duodenum to the front of the vertebral column.

The wall of the stomach consists of four coats: serous, muscular, areolar, and mucous.

The glands of the stomach are of three kinds: gastric, pyloric, and cardiac. These glands furnish the digestive enzymes of the stomach, namely: pepsin, renin, and hydrochloric acid.

_Arteries._—The arteries that supply the stomach are the gastric, and branches from the splenic and the hepatic.

It must be remembered that when a body is arterially injected after death, that the fluid only goes to the stomach walls and there ends in the capillary system. No doubt a little of this fluid will soak through into the inside of the stomach, and tend to preserve the contents of the stomach, but it must be added that if the stomach contains a considerable quantity of food and water, that there will not be enough fluid soak through the stomach wall to preserve the contents of the stomach and as a result gases arise which cause distention of the abdomen and perhaps purging from the mouth and nose. As a rule then it is safe to say that when we have purging from the mouth and nose, with a visible distention of the abdominal cavity, indicating gases in the stomach and the intestines that fluid has not reached the contents of the stomach and the fecal matter of the intestines, and therefore it will be necessary to introduce fluid to these parts, in order to preserve the contents, and prevent further formation of gases. The method for doing this will be given under cavity embalming.

=The Small Intestines.=—The small intestine is a convoluted tube, extending from the pyloric end of the stomach to the ileo-caecal valve where it terminates in the large intestines. It fills up the greater part of the abdominal and the pelvic cavity. It is about twenty feet in length and gradually diminishes in size from the commencement to the termination.

The small intestines are surrounded at the top and at the sides by the large intestines. The small intestines are held in place by the mesentery, a part of the peritoneum, which connects or fastens to the spine.

The small intestines are divisible into three portions: Duodenum, Jejunum, and the Ileum.

_Arteries._—The main arterial supply to the small intestines is through the superior mesenteric artery.

The superior mesenteric vein withdraws the main part of the blood from the small intestines.

=Duodenum.=—The duodenum has received its name from being about equal in length to the breadth of twelve fingers (ten inches).

It is the shortest, widest and the most fixed part of the small intestines, being closely and firmly attached to the posterior abdominal wall. It is not covered by the mesentery. The upper half of the duodenum is in the epigastric region and the lower half is in the umbilical region. It is practically in the median line of the body.

The duodenum is shaped like a horseshoe, the opening being directed toward the left. The arteries supplying the duodenum are the pyloric and the pancreatic duodenal branch of the superior mesenteric. The veins correspond to the arteries.

The pancreatic duct and the bile duct empty into the duodenum at its middle portion.

=Jejunum.=—The jejunum is the second portion of the small intestines, it derives its name from the latin word “jejunas,” meaning empty, because it was formerly supposed to be empty after death.

It is wider, thicker, more vascular and of a deeper color than the ileum. The jejunum is about eight feet in length or two-fifths of the length of the small intestines.

The arteries which supply the jejunum are the branches of the superior mesenteric artery. The veins are of the same name.

The jejunum is fastened to the posterior wall of the abdomen by an extensive fold of the mesentery.

=Ileum.=—The ileum is derived from a Greek word meaning to twist, and is so named on account of its numerous coils and convolutions. It is the third portion of the small intestines and is placed below the jejunum. It is much narrower and thinner than the jejunum, about twelve feet in length or three-fifths of the length of the small intestines. It is also attached to the posterior abdominal wall by means of the mesentery. The arteries which supply the ileum are the branches of the superior mesenteric artery. The veins are of the same name.

_The villi_ are minute projections on the mucous membrane of the small intestines. They are largest and most numerous in the duodenum and jejunum, and become fewer and smaller in the ileum. It is in the villi of the intestines that we find the termination of the mesenteric arteries, the beginning of the mesenteric veins and the commencement of the lacteals.

As the food passes down the intestines, having been previously prepared in the stomach and intestines for absorption, it comes in very close contact with the villi of the intestines and it is here that the nutrition from the food is absorbed through the villi wall into the lacteals, and hence carried to the receptaculum chylii.

=The Large Intestines.=—The large intestine extends from the termination of the ileum to the anus. It is about five or more feet in length or about one fifth of the whole extent of the intestinal canal. It is largest at its commencement at the caecum, and gradually diminishes in size as far as the rectum, where there is a dilatation of considerable size just above the anus.

The large intestine differs from the small intestine in its greater size, its more fixed position, its sacculated form.

The large intestine in its course describes an arch, which surrounds the convolutions of the small intestines. It commences in the right inguinal region, in a dilated part of the caecum. It ascends through the right lumbar and the right hypochondriac regions to the under surface of the liver, it here takes a bend to the left, the hepatic flexure, 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 splenic flexure, and descends through the left lumbar region to the left inguinal region, where it becomes convoluted and forms the sigmoid flexure; finally it enters the pelvic cavity and descends along the posterior wall to the anus.

The large intestine is supplied by the branches of the inferior mesenteric artery, and the veins are of the same name.

The large intestines are divided into the caecum, colon and rectum.

=Caecum.=—The caecum is the commencement of the large intestines, it is a large blind pouch situated below the ileo caecal valve. _The ileo caecal valve_ is the valve between the exit of the small intestines and the commencement of the large intestines. The caecum is held mostly in place by the folds of the peritoneum.

_The Vermiform Appendix._—The appendix is found only in the human, the higher apes, and the wombat, although in certain rodents a somewhat similar arrangement exists. The appendix is a long, narrow, worm shaped, musculo-membranous tube, which starts from the inner side of the posterior wall of the caecum, below and behind the termination of the ileum. It is the seat for a very common disease called appendicitis. It varies from one half to nine inches in length, its average being about three inches. Its diameter is from one eighth to one quarter of an inch.

=The Colon.=—The colon is divided into three parts, the ascending, transverse and the descending colon.

_The ascending colon_ is smaller than the caecum, with which it is continuous. It passes upward from its commencement at a point corresponding to the ileo-caecal valve, to the under surface of the right lobe of the liver, on the right of the gall bladder, where it is lodged in a shallow depression on the liver; here it bends abruptly inward to the left, forming the hepatic flexure. It is held to the posterior wall of the abdomen by folds of the peritoneum.

_The transverse colon_ is the longest part of the small intestines, passes transversely from the right to the left across the abdomen, opposite the confines of the epigastric and umbilical regions, where it curves downward beneath the lower end of the spleen, forming the splenic flexure. In its course the transverse colon describes an arch, the concavity of which is directed backward toward the vertebral column and a little upward.

This is the most movable part of the colon, only covered by peritoneum and held to the back wall by the folds of the peritoneum. The transverse colon is in relation, by its upper surface with the liver and gall bladder the great curvature of the stomach, and the lower end of the spleen; by its under surface with the small intestines; by its anterior surface with the anterior layers of the great omentum and the abdominal wall; its posterior surface on the right is in relation with the duodenum and on the left it is in contact with the convolutions of the jejunum and ileum.

_The descending colon_ passes downward through the left hypochondriac region and lumbar region along the outer border of the left kidney. At the lower end of the left kidney it turns inward where it terminates in the formation of the sigmoid flexure. The descending colon is held to the back wall by folds of the peritoneum.

The sigmoid flexure, the narrowest part of the colon, is situated in the left inguinal region and communicates with the rectum.

=The Rectum.=—The rectum is the terminal part of the large intestines, and extends from the termination of the sigmoid flexure to the anus. The adult rectum in male is from four to six inches in length, and in the female is from three to five inches in length.

_The anus_ is the terminal opening of the alimentary canal.

=Liver.=—The liver is the largest gland in the body, and is situated in the upper and right part of the abdominal cavity, occupying almost the whole of the right hypochondriac, the greater part of the epigastric, and extending almost to the middle of the left hypochondriac region.

In the male it weighs from fifty to sixty ounces, and in the female, from forty to fifty.

It is relatively much larger in the foetus, being about one-eighteenth of the body weight in the foetus, and in the adult, about one-thirty-sixth of the body weight.

Its greatest width is from seven to eight inches, is about twelve inches long, and in its greatest thickness about three inches.

The liver is very soft and is easily lacerated and friable; its color is a dark reddish brown. To obtain a correct idea of its shape, you might compare it to a wedge, the base of which is directed to the right, and thin edge toward the left.

The liver has five surfaces, superior, inferior, anterior, posterior and right lateral.

The liver has five lobes, right and left, caudate, quadrate, and lobus spigelii. It has five ligaments, right and left lateral or triangular, falciform, coronary and round. The liver has five fissures, the umbilical, the fissure of the ductus venosus, the transverse fissure, the fissure for the gall bladder, the fissure for the vena cava. These fissures can be represented by the letter H.

Fissure of | BACK | Fissure Ductus | | inferior L venosus | | vena R E | Transverse | cava I F ———————————+——————————————+—————————— G T Umbilical | | Fissure H fissure | FRONT | for gall T | | bladder | |

The liver is movable within certain narrow limits. It moves with respiration. On inspiration, it moves down with the diaphragm to a little below the right nipple line. The ligaments do not give the liver much support because they lie relaxed, but it does get its main support from the connective tissue which unites the liver to the diaphragm, the hepatic veins which join the vena cava and also by the intra-abdominal pressure resulting from the tonic contraction of the abdominal muscles.

Also when the abdominal tension is normal, the intestines are driven up, and become a bed for the liver.

The most important function is the secretion of the bile; it is also the excretor of deleterious matter and impurities. It also effects important changes of the blood in its passage through it, for the portal circulation.

The excretory apparatus of the liver consists (a) of the hepatic duct, (b) the gall bladder, (c) cystic duct, (d) the common bile duct.

The hepatic duct is formed by two main trunks nearly of equal size which issue from the liver, one from the right and one from the left lobe. The hepatic duct passes downward and to the right from one to two inches where it is joined at an acute angle with the cystic duct.

=The Gall Bladder.=—The bladder is a reservoir for the bile. It is a conical or pear-shaped sack, lying on the under surface of the right lobe of the liver. It is about four inches in length, one inch in depth and holds from eight to ten drams.

The cystic duct is about an inch and a half in length, and passes obliquely downward to the left from the neck of the gall bladder, and joins the hepatic duct.

The common bile duct (ductus communis choledochous) is the common excretory duct of the liver and the gall bladder, and is formed by the union of the cystic and hepatic ducts. It descends to the middle portion of the duodenum, where it unites with the pancreatic duct, the two passing obliquely through the wall of the descending portion of the duodenum. The tissues of the liver are nourished by the blood from the hepatic arteries.

=The Pancreas.=—The pancreas (the sweet bread) is a gland similar in structure to the salivary glands; is about seven inches long, of a grayish white color; its weight varies from two to six ounces. It is situated behind the stomach, and it secretes the pancreatic juice. It extends to the right in a part of the epigastric space. The tail lies above the left kidney, and is in contact with the lower end of the spleen and in the left hypochondriac region; the body lies behind the stomach and transverse colon and in front of the great aorta, portal vein and inferior vena cava. The arteries nourishing it are the large and small pancreatic, which are branches of the splenic artery.

The pancreatic duct is the principal excretory duct of the pancreas. It extends transversely from the left to the right through the substance of the pancreas.

After leaving the body of the pancreas, it unites with the common bile duct of the liver where it empties into the duodenum (first section of the small intestines after leaving the stomach).

The pancreatic duct carries pancreatic juice (a digestive fluid) from the pancreas to the duodenum.

=The Spleen.=—The spleen belongs to that class of bodies known as ductless glands and has no excretory duct; is oblong, flattened, soft, very brittle, very vascular, of a very dark bluish red color; is situated in the left hypochondriac region behind and to the left of the stomach; is five inches long, three inches wide and two inches thick and weighs about seven ounces. The vessels which nourish it are the splenic artery and splenic vein. Function. It is supposed to furnish blood corpuscles.

=The Kidneys.=—The kidneys are large glands, two in number and are situated from five to six inches apart or about three inches on either side of the median line in the right and left lumbar regions.

The upper extremity of the kidneys lies on the level of the twelfth dorsal vertebra and the lower extremity on the level of the third lumbar vertebra. Each kidney is four and one-half inches in length, two to two and one-half inches in breadth, a little more than one inch in thickness.

The weight of the kidney in the adult male is from four and one-half to six ounces each. In the adult female the weight would be from four to five and one-half ounces.

Their function is to separate from the blood certain waste products and an excess of water, the combination of which we know as urine. The principal products excreted by the kidneys from the blood along with water are ammonia and urea. The blood is taken to the kidneys by the renal arteries and the renal veins carry it back to the blood circulation.

The urine is then taken from the kidneys by the ureters and conveyed to the urinary bladder.

=The Ureters.=—The ureters are cylindrical tubes about sixteen inches in length and of diameter of a goose-quill.

=The Suprarenal Capsules.=—The suprarenal capsules belong to that class of bodies known as ductless glands and are two small flattened bodies of yellowish color, situated at the back of the abdomen, behind the peritoneum (the covering for all of the abdominal organs), and immediately above and in front of the upper end of each kidney. The name is derived from the position it occupies in relation to the kidney, supra meaning above, and renal pertaining to the kidneys.

The functions are as yet unknown. The suprarenal arteries furnish nourishment for the suprarenal capsules.

=The Pelvic Cavity.=—The pelvic cavity is that portion of the abdomen situated between the ilium and pubic bones, or in other words the extreme lowest portion of the abdominal cavity. The organs located within this cavity are the bladder in the male and the bladder and the uterus (womb) in the female.

=The Bladder.=—The urinary bladder is a reservoir for the urine, situated in the pelvic cavity behind the pubic bone. In life it is supplied with blood by the anterior branches of the internal iliac arteries accompanied by the internal iliac veins.

=The Uterus.=—The uterus is the organ of gestation, receiving the fecundated ovum into its cavity, retaining it, and supporting it during the development of the foetus, and becoming the principal agent in its expulsion at the time of parturition (delivery). It is nourished in life by branches of the internal iliac artery, which is accompanied by the iliac vein.

The uterus is situated in the pelvic cavity between the rectum and the bladder, and is held in position by the lateral and round ligaments on each side. The uterus is about 3 inches in length, 2 inches in breadth and weighs from one to two ounces. It is composed of three coats, external serous, middle muscular, and internal mucous.

The serous coat, derived from the peritoneum, is thin and vascular.

The muscular coat is the chief coat, it is dense, firm, of a grayish color and cuts like cartilage.

The mucous coat is thin, smooth and closely adherent to the muscular coat. It is highly vascular.

The blood supply to the uterus is the uterine arteries which are the posterior branches of the internal iliac arteries, and the ovarian arteries which are branches of the aorta. These break up in capillaries and form a fine network plexus in the coats of the uterus.

The veins are of large size and are the uterine which empty into the internal iliac veins and the ovarian veins. On the right side the ovarian vein empties into the ascending vena cava, and on the left side into the renal vein.

=Prostate.=—The prostate gland is a pale, firm glandular body, which surrounds the neck of the bladder in the male. Its shape and size resembles a horse chestnut. It weighs from one-half to one ounce and measures one and one-half inches across and three quarters of an inch deep. Its structure is inclosed by a firm thin fibrous capsule. Its substance is of a pale reddish grey color and is composed of glandular substance and muscular tissue.

The arteries that supply the prostate are derived from the internal pubic, a branch of the internal iliac.

The veins form a plexus around the gland and communicate with veins which empty into the internal iliac veins. Its function is to secrete an opaque fluid.

=The Peritoneum.=—During life and in the uncut corpse the peritoneal cavity is air-tight. It is not a real cavity, as muscular tension and atmospheric pressure permit no vacant space to form. When the surgeon or embalmer opens the abdomen, the peritoneal cavity is at that moment produced.

The peritoneum is the largest serous membrane in the body. In the male it is a closed sac, a part of which is applied against the abdominal sides, while the remainder is reflected over the contained viscera. In the female it is not a closed sac, since the free extremities of the fallopian tubes open directly into the peritoneal cavity.

_The parietal peritoneum_ is that portion applied against the abdominal sides.

_The visceral peritoneum_ is that portion reflected over the viscera.

The peritoneum consists of two sacs.

_The greater sac_ lines the greater part of the abdominal cavity as almost all of the viscera are covered by it.

_The lesser sac_ is placed behind the stomach. These two sacs communicate with each other by a narrow orifice called the _Foramen of Winslow_.

The peritoneum, as it covers different organs or sets of organs, receives special names.

_The lesser omentum_ consists of two layers, these split to envelope the stomach.

_The greater omentum_ consists of four layers. Two of these layers extend from the stomach and together with two other layers of the same structure which envelope the transverse colon, form an apron for the intestines.

_The mesentery_ consists of two layers which invests the small intestines. Between the two layers of the mesentery we find the blood vessels, nerves, lacteals, and glands, leading to and from the intestines. The mesentery is fan shaped, and is attached to the second lumbar vertebra. The length of the mesentery fan is about eight inches from commencement to termination at intestine. It extends the whole length of the intestines, which is about twenty feet.