HUMAN ANATOMY – VOLUME 1

Fig. 144. Pancreas; gallbladder; bile ducts and duodenum. Posterior aspect.

1 — commone hepatic duct; 2 — cystic duct; 3 — neck of gallbladder; 4 — body of gallbladder; 5 — bile duct; 6 — fundus of gallbladder; 7 — duodenum; 8 — sphincter of common bile duct; 9 — pancreatic duct and its sphincter; 10 — sphincter of hepato-pancreatic ampulle (Oddi’s sphincter); 11 — peritoneum; 12 — head of pancreas; 13 — superior mesenteric vein; 14 — superior mesenteric artery; 15 — tail of pancreas; 16 — body of pancreas; 17 — splenic vein; 18 — hepatic portal vein.

ic arteries and veins, and the celiac plexus. The a n t e r o-i n f e r i o r s u r - f a c e is narrow and is partially covered by peritoneum. The inferior and superior anterior surfaces are divided by the anterior border of the gland. At the level of the anterior border lies the mesentery root of the transverse colon.

The t a i l o f t h e p a n c r e a s extends to the left, where it lies against the visceral surface of the spleen, somewhat below its hilum. Behind the tail lies the left adrenal gland and the upper part of the left kidney.

The parenchyma of the pancreas is divided into the lobules by connective tissue trabeculae, which begin from the capsule of the gland. The lobules contain the secretory compartments, which resemble hollow pouches 100–500 mm in size. Each excretory compartment consists of 8–14 pyramid-shaped cells called exocrine pancreatocytes (acinocytes) (Fig. 145). The excretory cells are situated on a basement membrane. From the cavities of excretory compartments extend the intercalary excretory ducts, which are lined with simple squamous epithelium. Intercalary ducts flow into intralobular ducts, which are lined with simple cuboidal epithelium. The interlobular ducts pass through interlobular connective trabeculae. The

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Fig. 145. Construction of the pancreatic acinus (acc. to V. G. Eliseev).

1 — nerve fiber; 2 — intercalary duct; 3 — centroacinal cells; 4 — acinal cells; 5 — secretory granules of apical parts of cells; 6 — haemocapillaries.

walls of the interlobular ducts are formed by simple columnar epithelium and its lamina propria. Interlobular ducts flow into the main pancreatic gland.

The p a n c r e a t i c d u c t (d ú c t u s p a n c r e á t i s), or duct of Wirsung, passes inside the gland, closer to its posterior surface. This duct begins in the tail of the gland and passes through the body and the head, receiving the smaller interlobular ducts. It opens into the descending part of the duodenum on the major duodenal papilla, after uniting with the common bile duct. In the end of the pancreatic duct its wall contains a sphincter, formed by a thickening of circular smooth muscular fascicles.

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Often the pancreatic and bile ducts have separate openings in the duodenal wall, in which case the major papilla may or may not be absent.

Formed in the head of the pancreas is an accessory pancreatic duct (the duct of Santorini), which opens into the duodenum on top of the minor duodenal papilla. Sometimes there is an anastomosis between the main and accessory pancreatic ducts.

The walls of the main and accessory ducts are lined with columnar epithelium. The epithelium of the pancreatic excretory duct system contains goblet cells, which produce mucus, and endocrinocytes. The endocrine cells of the ducts secrete pancreozinin and cholecystokinin. The lamina propria of interlobular, accessory and main pancreatic ducts contains numerous mucous glands.

The e n d o c r i n e p a r t o f t h e p a n c r e a t i c g l a n d is formed with p a n c r e a t i c i s l e t s (islets of Langerhans), which are, consist of groups of endocrinocytes. They are located primarily in the tail of the pancreas. These islets be round, oval or, sometimes, strip or stellar shape. Their total quantity ranges between 0.2 and 1.8 million. Their diameter varies from 100 to 300 mm, and weight — from 0.7 to 2.6 g. There are several different types of endocrinocytes, which form these islets. Their structure is described in the «Endocrine system» section.

I n n e r v a t i o n of the pancreas: branches of vagus nerves (mainly right vagus nerve), sympathetic nerves from the celiac plexus.

B l o o d s u p p l y: anterior and posterior superior pancreaticoduodenal arteries (from gastroduodenal artery), inferior pancreaticoduodenal artery (from the superior mesenteric artery).

Ve n o u s o u t f l o w: pancreatic veins (into superior mesenteric, splenic and other veins of the portal vein system).

Ly m p h o u t f l o w: pancreatic, pancreaticoduodenal, pyloric and lumbar lymph nodes.

Questions for revision and examination

1.What organs adjoin the posterior surface of the pancreas? What organs adjoin its anterior surface?

2.Describe the structure of exocrine secretory compartments of the pancreas and its excretory ducts.

3.How many excretory ducts does the pancreas have?

PERITONEUM

The peritoneum (peritóneum) is a thin serous membrane, which lines the abdominal cavity, covering many of its organs. It is formed by several alternating layers of collagen and elastic fibers, lined by squamous me-

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sothelial cells. Its surface area is approximately 1.7 m2. The peritoneum carries out integumentary and protective functions. It contains immune structures (lymphoid nodules) and adipose tissue (fat storage). Duplications of peritoneum form ligaments, which fixate internal organs, preventing their excessive movement. The peritoneum, which lines the walls of the abdomen, is called p a r i e t a l p e r i t o n e u m, and that, which covers its organs is called v i s c e r a l p e r i t o n e u m (Fig.146). When passing between the organs this membrane forms ligaments (folds). The sheets of peritoneum, which pass onto the organs from the posterior abdominal wall, form the mesentery of these organs. Between the sheets of the mesentery there are blood vessels and nerves. The beginning part of the mesentery, located on the posterior abdominal wall, is called the root of the mesentery. The space within the abdominal cavity, which is confined by peritoneum, is called t h e p e r i t o n e a l c a v i t y (c á v u m p e r i t o n e i). At the bottom the peritoneal cavity descends into the pelvis. In men this cavity is completely closed. In women it communicates with the external environment through the abdominal openings of the uterine tubes, the uterus and vagina. The peritoneal cavity contains a small amount of serous fluid,

Fig. 146. Abdominal cavity. Horizontal cut of human body between LII and LIII (acc. to R.D.Sinelnikov).

1 — retroperitoneal space; 2 — kidney; 3 — colon; 4 — peritoneal space; 5 — parietal peritoneum; 6 — rectus abdominis muscle; 7 — mesentery; 8 — small intestine; 9 — visceral peritoneum; 10 — aorta; 11 — inferior vena cava; 12 — duodenum; 13 — psoas major muscle.

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which moistens the peritoneum, enabling the organs to glide freely against each other.

The relationship of the peritoneum with different organs of the abdominal cavity varies. For example, the kidneys, adrenal glands, ureters, most of the duodenum, the pancreas, abdominal aorta and the inferior vena cava lie retroperitoneally. They are covered by peritoneum only from the front.

Fig. 147. Posterior surface of anterior abdominal wall.

Organs, which are covered by peritoneum from three sides (ascending and descending colons, middle part of the rectum)

are called mesoperitoneal. Organs, which are covered by peritoneum on all sides, are called intraperitoneal. This last group includes the stomach, jejunum and ileum, transverse and sigmoid colons, upper part of the rectum, spleen and liver.

The peritoneum of the anterior abdominal wall at the top passes onto the diaphragm; at the sides — onto the lateral abdominal walls; and at the bottom — the inferior wall of the pelvic cavity. On the front abdominal wall there are 5 well-defined folds (Fig. 147). The m e d i a n u m b i l i c a l f o l d passes from the apex of the bladder to the umbilicus, and contains the obliterated urinary duct. To its sides are the paired m e d i a l u m b i l i c a l f o l d s, which contain the obliterated umbilical arteries. The l a t e r a l u m - b i l i c a l f o l d s contain the inferior epigastric arteries. Between these folds are fossae, which are the weak points of the abdominal wall, and are a common site of inguinal hernias. Above the bladder, at the sides of the median umbilical fold, are the right and left s u p r a v e s i c a l f o s s a e (usually hernia do not form here). Between the medial and lateral umbilical folds are the m e d i a l i n g u i n a l f o s s a e, which correspond to the super-

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ficial inguinal rings. To the outside of the lateral umbilical folds are the lateral inguinal fossae, which correspond to the deep inguinal rings.

The parietal peritoneum above the umbilicus forms the f a l c i f o r m l i g a m e n t of the liver. This ligament stretches between the anterior abdominal wall and diaphragm and the diaphragmatic surface of the liver, where its sheets continue into visceral peritoneum (Fig. 148). Inside the free lower (anterior) margin of this ligament passes the r o u n d l i g a - m e n t (ligamentum téres), which is an obliterated umbilical vein. In the back, the sheets of the falciform ligament pass into the coronal ligament of the liver. The c o r o n a r y l i g a m e n t is stretched in the frontal plane, and is formed by the transition between visceral peritoneum of the liver and parietal peritoneum of the posterior abdominal wall. At the sides the coronal ligament spreads out, forming the r i g h t and l e f t t r i a n g u l a r l i g a m e n t s. The visceral peritoneum of the inferior (visceral) surface of

Fig. 148. Position of intestines and peritoneum. Median sagittal section of human body.

1 — liver; 2 — hepatogastric ligament; 3 — omental bursa; 4 — pancreas; 5 — duodenum; 6 — mesentery; 7 — rectum; 8 — urinary bladder; 9 — small intesine; 10 — transverse colon; 11 — cavity of greater omentum; 12 — transverse mesocolon; 13 — stomach.

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theliver covers the bottom surface of the gallbladder. From the visceral surface of the liver two peritoneal sheets extend to the lesser curvature of the stomach and the beginning part of the duodenum, forming the hepatogastric and hepatoduodenal ligaments. Inside the hepatoduodenal ligament lie, from left to right, the common bile duct, the portal vein and the hepatic artery, nerves and lymph vessels and nodes. The h e p a t o g a s t r i c and h e p a t o d u o d e n a l l i g a m e n t s together form the minor omentum (omentum minus).

The sheets of the visceral peritoneum of the anterior and posterior walls of the stomach continue from its greater curvature downwards, to the upper inlet into the lesser pelvis. At this level (or a little higher) the two sheets turn back and ascend to the posterior abdominal wall (at the level of the pancreas). These four sheets of visceral peritoneum form the g r e a t e r o m e n t u m (o m é n t u m m á j u s). At the level of the transverse colon all four sheets accrete with the taenia coli, which is situated on its anterior surface. From there the posterior two sheets of peritoneum pass over the transverse mesocolon onto the posterior abdominal wall. One of these sheets continues onto the anterior surface of the pancreas, and the other continues downwards, becoming the upper sheet of the t r a n s v e r s e m e s o c o l o n. The part of the greater omentum, which stretches between the greater curvature of the stomach and the transverse colon, is called the g a s t r o c o l i c l i g a m e n t. The greater omentum covers in the front the jejunum and part of the ileum. Two sheets of peritoneum, which stretch from the greater curvature of the stomach to the hilum of the spleen, form the g a s t r o s p l e n i c l i g a m e n t. There is also a g a s t r o d i a p h r a g m a t i c and d i a p h r a g m a t i c o s p l e n i c l i g a m e n t s.

T h e p e r i t o n e a l c a v i t y is divided into upper and lower levels, the border between which is formed by the transverse colon and its mesentery. The upper level is confined by the diaphragm, lateral abdominal walls and the transverse colon with its mesentery. The transverse mesocolon is attached to the posterior abdominal wall at the level of the tenth ribs. The upper level of the peritoneal cavity contains the stomach, liver and spleen. Retroperitoneally at this level lie the superior part of the duodenum and the pancreas. The upper level has three separate compartments, called the hepatic, pregastric and omental bursae. The h e p a t i c b u r s a is situated in the right subcostal region and contains the right lobe of the liver. It has a suprahepatic fissure (i n f r a d i a p h r a g m a t i c s p a c e) and an infrahepatic fissure (i n f r a h e p a t i c s p a c e). It is separated from the other bursae by the falciform and coronal ligaments. The hepatic bursa communicates with the pregastric bursa and the right lateral canal.

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The p r e g a s t r i c b u r s a is situated in the frontal plane in front of the stomach and lesser omentum, between the falciform ligament on the right and the diaphramaticocolic ligament on the left. Its superior wall is formed by the diaphragm, and the inferior wall — by the transverse colon. In front it is bounded by the anterior abdominal wall. On the right this bursa communicates with the infrahepatic fissure and the omental bursa, and on the left — with the left lateral canal.

The o m e n t a l b u r s a (b ú r s a o m e n t á l i s) is situated behind the stomach, lesser omentum and gastrocolic ligament. At the top the omental bursa is bordered by the caudate liver lobe; at the bottom—by the posterior lamina of the greater omentum, which accretes with the mesentery of the transverse colon. In the back the omental bursa is bordered by parietal peritoneum, which covers the aorta, inferior vena cava, upper pole of the left kidney, left adrenal gland and pancreas. The cavity of the omental bursa has the shape of a fissure, situated in the frontal plane, and contains three recesses. The s u p e r i o r omental r e c e s s is situated between the lumbar part of the diaphragm and the caudate liver lobe. The s p l e n i c r e c e s s is situated between the gastrosplenic ligament, the diaphragmaticosplenic ligament and the hilum of the spleen. The i n f e r i o r omental r e c e s s is bordered by the gastrocolic ligament at the top and front, and, at the bottom, by the posterior lamina of the greater omentum (accreted with the transverse colon mesentery). The omental bursa communicates with the hepatic bursa (infrahepatic fissure) through the e p i p l o i c (Winslow’s) f o r a m e n. This foramen is 3–4 cm wide, and is limited in the front by the hepaticoduodenal ligament, and in the back — by parietal peritoneum, which covers the inferior vena cava. At the top the epiploic foramen is limited by the caudate lobe of the liver, and at the bottom — by the superior part of the duodenum.

The lower level of the peritoneal cavity is situated beneath the transverse colon and its m e s e n t e r y. At the bottom it is limited by the peritoneum, which lines the floor of the pelvic cavity. This level contains two paracolic grooves (lateral canals) and two mesenteric sinuses (Fig.149). The r i g h t p a r a c o l i c g r o o v e (r i g h t l a t e r a l c a n a l) is situated between the right abdominal wall and the ascending colon. The l e f t p a r a c o l i c g r o o v e (l e f t l a t e r a l c a n a l) is bordered by the left abdominal wall and the descending colon. The mesentery of the small intestine divides the two mesenteric sinuses. The r o o t o f t h e m e - s e n t e r y extends on the posterior abdominal wall between the levels of the duodenojejunal transition on the left and the sacroiliac joint on the right. The r i g h t m e s e n t e r i c s i n u s is limited on the right by the ascending colon; at the top by the root of the transverse mesocolon; and

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Fig. 149. Mesenteric sinuses; ligaments of peritoneum within abdominal cavity. Part of transverse colon is removed.

1 — liver; 2 — falciform ligament; 3 — round ligament of the liver; 4 — coronal ligament; 5 — left triangular ligament; 6 — gastrophrenic ligament; 7 — stomach; 8 — spleen; 9 — hepatogastric ligament; 10 — gastrolienal ligament; 11 — hepatoduodenal ligament; 12 — anterior wall of omental foramen; 13 — mesocolon; 14 — transverse colon; 15 — superior duodenal fossa; 16 — descending colon; 17 — root of mesentery; 18 — sigmoid colon; 19 — intersigmoid recess; 20 — rectum; 21 — appendix; 22 — mesoappendix; 23 — inferior ileocaecal recess; 24 — caecum; 25 — jejunum; 26 — superior ileocaecal recess; 27 — ascending colon; 28 — transverse

colon; 29 — right triangular ligament; 30 — omental foramen.

on the left by the root of the jejunal and ileal mesenteries. Within these boundaries, retroperitoneally lies the bottom of the descending part and the horizontal part of the duodenum, lower part of the head of pancreas, part of the inferior vena cava, right ureter, vessels, nerves and lymph nodes.

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Fig. 150. Peritoneum of female pelvic cavity.

1 — rectum; 2 — recto-uterine pouch; 3 — rectal ampulla; 4 — posterior part of vaginal fornix; 5 — external orifice of uterus; 6 — anterior part of vaginal fornix; 7 — external anal sphincter; 8 — internal anal sphincter; 9 — anus; 10 — vagina; 11 — vaginal orifice; 12 — labium majus; 13 — labium minus; 14 — head of clitoridis; 15 — body of clitoridis; 16 — urethra; 17 — urinary bladder; 18 — anterior lip of external os of uterus; 19 — posterior lip of external os of uterus; 20 — vesico-uterine pouch; 21 — round ligament of uterus; 22 — uterus; 23 — uterine tube; 24 — external iliac artery and vein; 25 — ovary; 26 — suspensory ligament of ovary; 27 —

ovarian fimbria; 28 — ureter.

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