Pancreas Anatomy – Diagram, Location, Relations, Functions

The pancreas develops from the anteroposterior part of the middle part of the primary intestinal tube, forming from two endodermal protrusions, or primordia, – the dorsal and ventral. The main part of the gland and the accessory excretory duct develop from the dorsal anlage. The ventral anlage grows from the sides of the common bile duct, at the place of its confluence with the duodenum; from it, the main pancreatic duct and glandular tissue are formed, which subsequently merge with the dorsal anlage.

In an adult, the shape, size and weight of the gland vary over a wide range. According to the shape, three types of glands are distinguished: spoon-shaped, or lingual, hammer-shaped and L-shaped. It is not possible to establish any connection between the shape of the pancreas and the shape of the abdomen, as well as the structure of the body. When viewed from above, it can be seen that the pancreas bends twice, bending around the spine. The anterior bend – with a bulge forward (omental tubercle) is formed when the gland crosses the spine along the midline, and the posterior – with a bulge backward – at the place of transition of the gland from the anterior surface of the spine to the posterior abdominal wall.

In the gland, a head, body and tail are distinguished. There is a narrowing between the head and the body – a neck; at the lower semicircle of the head, as a rule, a hook-shaped process is noticeable. The length of the gland ranges from 14-22 cm, the diameter of the head is 3.5-6.0 cm, the thickness of the body is 1.5-2.5 cm, the length of the tail is up to 6 cm.The weight of the gland is from 73 to 96 g.

Since the pancreas is located retroperitoneally, behind the stomach, it can be visualized without dissecting the ligaments of the stomach and liver only with severe gastroptosis and emaciation. In such cases, the gland is located above the lesser curvature, lies almost open in front of the spine, covering the aorta in the form of a transverse ridge. Normally, the head of the pancreas performs the horseshoe of the duodenum, and its body and tail, thrown through the inferior vena cava, spinal column and aorta, extend to the spleen at the level

I-III lumbar vertebrae. In the body of the gland, the anterior-superior, anteroposterior and posterior surfaces are differentiated. The projection of the body onto the anterior abdominal wall is located in the middle between the xiphoid process and the navel. In the narrowed part of the organ (neck) between the lower horizontal part of the duodenum and the head of the gland, the superior mesenteric vein passes, which, merging with the splenic vein, forms the portal vein; to the left of the mesenteric vein is the superior mesenteric artery. The splenic artery and vein pass at or below the upper edge of the pancreas. The line of attachment of the mesocolon transversum runs along the lower edge of the gland. As a result, in acute pancreatitis, persistent intestinal paresis occurs already in the initial stage. The tail of the pancreas runs over the left kidney. Behind the head are the inferior vena cava and portal veins, as well as the vessels of the right kidney; the vessels of the left kidney are somewhat covered by the body and the tail of the gland. In the corner between the head of the pancreas and the transition of the upper horizontal part of the duodenum into the descending part, the common bile duct passes, which is very often completely surrounded by the tissue of the pancreas and flows into the large papilla of the duodenum.

The additional pancreatic duct also flows into the duodenum, which, as the common bile and pancreatic ducts, has many options for confluence.

The main pancreatic duct is located along the entire gland. Usually it goes centrally, but deviations from this position by 0.3-0.5 cm are possible, more often from behind. On the transverse section of the gland, the duct opening is rounded, whitish in color. The length of the duct ranges from 14 to 19 cm, the diameter in the area of ​​the body is from 1.4 to 2.6 mm, in the area of ​​the head to the point of confluence with the common bile duct – from 3.0-3.6 mm. The main pancreatic duct is formed as a result of the fusion of the first-order intra- and interlobular excretory ducts (up to 0.8 mm in diameter), which, in turn, are formed by the fusion of the second-fourth-order ducts. Throughout its length, the main duct receives from 22 to 74 ducts of the first order. There are three types of structure of the ductal network of the gland. In the loose type (50% of cases), the main duct is formed from a large number of small excretory ducts of the first order, flowing at a distance of 3-6 mm from each other; with the main type (25% of cases) – from large ducts of the first order, flowing at a distance of 5-10 mm; in the intermediate type, from small and large ducts. The accessory pancreatic duct is located in the head of the gland. It is formed from the interlobular ducts of the lower half of the head and the hook-shaped process. The accessory duct can open into the duodenum, into the small duodenal papilla on its own, or flow into the main pancreatic in the intermediate type, from small and large ducts. The accessory pancreatic duct is located in the head of the gland. It is formed from the interlobular ducts of the lower half of the head and the hook-shaped process. The accessory duct can open into the duodenum, into the small duodenal papilla on its own, or flow into the main pancreatic in the intermediate type, from small and large ducts. The accessory pancreatic duct is located in the head of the gland. It is formed from the interlobular ducts of the lower half of the head and the hook-shaped process. The accessory duct can open into the duodenum, into the small duodenal papilla on its own, or flow into the main pancreatic

sky duct, that is, do not have an independent outlet into the intestine. The relationship between the main pancreatic and common bile ducts is of great importance in the pathogenesis of pancreatitis and for therapeutic measures. There are four main variants of the topographic-anatomical relationships of the end sections of the ducts.

1. Both ducts form a common ampulla and open into the large duodenal papilla. The ampoule length ranges from 3 to 6 mm. The main part of the muscle fibers of the sphincter of Oddi is located distal to the junction of the ducts. This variant occurs in 55-75% of cases.

2. Both ducts open together into a large duodenal papilla, but their fusion occurs at the very place of confluence, so there is no common ampulla. This variant occurs in 20-33% of cases.

3. Both ducts open into the duodenum separately at a distance of 2-5 mm from each other. In this case, the main pancreatic duct has its own muscle pulp. This option occurs in 4-10% of cases.

4. Both ducts run close to each other and open into the duodenum on their own, without forming ampoules. This option is rarely seen.

Being in the closest anatomical relationship with the biliary tract and the duodenum, the main pancreatic duct and the entire pancreas are involved in the pathological processes developing in this zone.

The anterior surface of the pancreas is covered with a very thin sheet of the peritoneum, which goes down to the mesocolon transversum. Often this leaf is called the capsule of the pancreas, although the latter, as an organ located retroperitoneally, does not have any capsule.

The question of the presence of its own capsule of the gland is controversial. Most surgeons and anatomists believe that the pancreas has a dense (Vorontsov I.M., 1949; Konovalov V.V., 1968) or a thin capsule (Saisaryants G.A., 1949), which must be dissected in the treatment of acute pancreatitis (Petrov B.A., 1953; Lobachev SV., 1953; Ostroverkhov G.E., 1964, etc.). However, V.M. Voskresensky (1951) and N.I. Leporsky (1951) deny the existence of the capsule, believing that the parietal peritoneum or dense layers of connective tissue surrounding the gland are usually taken for it. According to N.K. Lysenkov (1943), it is due to the absence of the capsule that the lobular structure of the gland is so clearly visible. A number of anatomy manuals do not mention the capsule, but say that the pancreas is covered in front by the peritoneum, which makes up the posterior wall of the omental bursa. A.V. Smirnov et al. (1972) used the technique of histotopographic cuts in order to determine the presence of a capsule. The gland was sectioned in three different planes. 1 study showed that the gland is covered with a narrow strip of connective tissue, consisting of thin collagen fibers. This strip has the same thickness throughout; connective tissue partitions are removed from it inside the organ, dividing the parenchyma of the gland into separate lobules. These partitions in the area of ​​the tops of the lobules melt together, due to which each lobule has its own connective tissue capsule. It is extremely difficult to separate the capsule from the parenchyma, since it breaks easily. that the gland is covered with a narrow strip of connective tissue, consisting of thin collagen fibers. This strip has the same thickness throughout; connective tissue partitions are removed from it inside the organ, dividing the parenchyma of the gland into separate lobules. These partitions in the area of ​​the tops of the lobules melt together, due to which each lobule has its own connective tissue capsule. It is extremely difficult to separate the capsule from the parenchyma, since it breaks easily. that the gland is covered with a narrow strip of connective tissue, consisting of thin collagen fibers. This strip has the same thickness throughout; connective tissue septa are removed from it inside the organ, dividing the parenchyma of the gland into separate lobules. These partitions in the area of ​​the tops of the lobules melt together, due to which each lobule has its own connective tissue capsule. It is extremely difficult to separate the capsule from the parenchyma, since it breaks easily. due to which each lobule has its own connective tissue capsule. It is extremely difficult to separate the capsule from the parenchyma, since it breaks easily. due to which each lobule has its own connective tissue capsule. It is extremely difficult to separate the capsule from the parenchyma, as it breaks easily.

Apparently, it should be considered that, even if a thin capsule exists, it is so tightly welded to the parietal peritoneum, tearing the anteroinferior surface of the gland, that it is not possible to separate them even with careful hydraulic dissection. In addition, this capsule peritoneum is closely related to the parenchyma of the gland, and it is impossible to separate it from the latter without the risk of damaging the gland tissue. Therefore, the point of view of practical surgery does not matter whether there is a peritoneum-capsule or just a peritoneum, the main thing is that the formation is inseparable from the parenchyma of the gland.

The fixation of the pancreas is carried out by four ligaments, which are folds of the peritoneum. This is the left pancreatic-gastric ligament, in which the left gastric artery passes, the right pancreatic-gastric ligament, passing to the terminal section of the lesser curvature of the stomach, the pancreas-splenic ligament, which runs from the tail of the pancreas to the gate of the spleen , and the pancreatic-duodenal ligament, rather weakly expressed. IN AND. Kochiashvili (1959) also notes his own ligament of the hook-shaped process. The pancreas is the most fixed organ of the abdominal cavity, which is due to its ligamentous apparatus, intimate connection with the duodenum and the end section of the common bile duct, located next to the large serial and venous trunks.

The retroperitoneal arrangement of the organ, as well as the adjacent transition of the peritoneum from the anterior surface of the gland to other organs, determine the expansion of false cysts, which, as a rule, form where the peritoneum is least developed, that is, in the omental bursa.

The blood supply to the pancreas (Fig. 1) is carried out from ex sources: 1) the gastro-duodenal artery (a. Gastroduodena-); 2) splenic artery (a. Lienalis); 3) lower pancreatoduodenal-.IX arteries (a. Pancreatoduodenalis inferior).

The gastro-duodenal artery originates from the common hepatic artery and, turning downwards, goes medially from the duodenal ulcer; in front of the head of the pancreas, it is divided into terminal branches that supply blood to the head of the gland, the duodenum and part of the omentum.

The splenic artery is the largest branch of the celiac trunk. Occasionally, it can extend directly from the aorta or from the superior mesenteric artery. The place where the splenic artery begins is usually at level I of the lumbar vertebra. The artery is located above the splenic vein in the groove of the splenic artery, goes horizontally, curving upward, along the anterior edge of the pancreas. In 8% of cases, it lies behind the pancreas, and in 2% in front of it. Through the phrenic-splenic ligament, the artery approaches the spleen, where it divides into its terminal branches. To the pancreas, the splenic artery gives off 6-10 small pancreatic arteries, thus supplying blood to the body and tail of the pancreas. Sometimes, at the very beginning of the splenic artery, the dorsal artery of the pancreas approaches the pancreas, passing posteriorly. It anastomoses with the posterior duodenal and inferior pancreatic-duodenal arteries.

Pancreas Anatomy (anatomy where is the pancreas) - lies behind the stomach on the posterior abdominal wall in the regio epigastrica.

Fig. 1. Blood supply to the pancreas

1 – a. hepatica communis;

2 – a. gastrica sinistra;

3 – truncus coeliacus;

4 – a. lienalis;

5 – a. mesenterica superior;

6 – a. pancreaticoduodenalis inferior anterior;

– a. pancreaticoduodenalis inferior posterior;

8 – a. pancreaticoduodenalis superior anterior;

9 – a. gastro-epiploica dextra;

10 – a. pancreaticoduodenalis superior posterior;

11 – a. gaslroduodenalis;

12 – a. hepatica propria;

13 – a. pancreatica inferior;

14 —- a. pancreatica magna;

15 – a. pancreatica caudalis

In 10% of cases, the inferior pancreatic artery departs from the distal part of the splenic artery, which supplies the body and tail of the pancreas and, anastomosed with the arterial vessels of the head, forms a large artery of the pancreas. The lower pancreatoduodenal arteries branch off from the superior mesenteric artery. They supply blood to the lower horizontal part of the duodenum and give branches along the posterior surface of the head to the lower edge of the pancreatic body. The superior mesenteric artery begins from the anterior wall of the aorta at the level of the I-II lumbar vertebrae at a distance of 0.5-2 cm from the celiac trunk (but it can also branch off together with the celiac trunk and the inferior mesenteric artery) and passes in front of the lower horizontal part of the duodenum, to the left of the superior mesenteric vein, between the two sheets of the mesentery. Its beginning obliquely crosses the left hepatic vein posteriorly, and in front – the splenic vein and pancreas (the place of transition of the head into the body of the gland). The artery exits below the pancreas, then descends downward. Most often, it turns to the right and forks to the right of the aorta.

The outflow of blood from the pancreas occurs along the posterior superior pancreatoduodenal vein, which collects blood from the head of the gland and carries it into the portal vein; the anterior superior pancreatoduodenal vein, which flows into the superior mesenteric vein system; the lower pancreatoduodenal vein, which flows into either the superior mesenteric or small intestinal vein. From the body and tail, blood flows through the small pancreatic veins through the splenic vein into the portal vein.

The lymphatic vessels of the pancreas form a dense network, widely anastomosed with the lymphatic vessels of the gallbladder, bile duct. In addition, lymph flows to the adrenal glands, liver, stomach, and spleen.

The sources of the lymphatic system of the pancreas are the gaps between the cells of the glandular tissue. Merging with each other, tissue gaps form tortuous lymphatic capillaries with bulbous thickenings. The capillaries also merge, forming lymphatic vessels, which are widely anastomosed with each other. Distinguish between deep lymphatic network of the pancreas, consisting of small vessels, and superficial, formed by vessels of a larger caliber. With an increase in the caliber of the vessel and as it approaches the regional lymph node, the number of valves in it increases.

The pancreas is surrounded by a large number of lymph nodes. According to A.V. Smirnov (1972), all regional lymph nodes of the first order are divided into 8 groups.

1. Lymph nodes along the splenic vessels. They consist of three main chains that lie between the splenic vessels and the posterior surface of the pancreas. The outflow of lymph goes from the body of the gland in three directions: to the nodes in the area of ​​the gate of the spleen, to the lymph nodes of the celiac group and the cardiac part of the stomach.

2. Lymph nodes located along the hepatic artery and lying in the thickness of the hepatic-duodenal ligament. They carry out the outflow of lymph from the upper half of the head of the gland into the second-order lymph nodes located in the region of the celiac artery trunk, around the aorta and the inferior vena cava.

3. Lymph nodes along the superior mesenteric vessels. They are responsible for the outflow of lymph from the lower part of the head of the gland into the para-aortic lymph nodes and into the right lumbar lymphatic trunk.

4. Lymph nodes along the anterior pancreatic-duodenal groove, lying between the head of the gland and the duodenum. The outflow of lymph goes from the anterior surface of the head of the gland to the lymph nodes of the mesentery of the transverse colon and hepato-duodenal ligament.

5. Lymph nodes along the posterior pancreatic-duodenal sulcus, located retroperitoneally. Responsible for the outflow of lymph from the posterior surface of the head to the lymph nodes of the hepato-duodenal ligament. With the development of an inflammatory process in this group or cancerous lymphangitis, massive adhesions occur with the common bile duct, portal and inferior vena cava, and the right kidney.

6. Lymph nodes along the anterior edge of the pancreas. They are located in a chain along the line of attachment of the mesentery of the transverse colon to the head and body of the gland. The outflow of lymph goes mainly from the body of the gland to the celiac group of nodes and to the lymph nodes of the spleen gates.

7. Lymph nodes in the tail of the gland. They are located in the thickness of the pancreas-splenic and gastro-splenic ligaments. They drain lymph from the tail of the gland to the lymph nodes of the hilum of the spleen and the greater omentum.

8. Lymph nodes at the confluence of the common bile duct with the main pancreatic duct. Outflow of lymph from the lymphatic vessels accompanying the main pancreatic duct is carried out into the celiac group of nodes, the superior mesenteric and along the hepato-duodenal ligament.

All 8 groups anastomose with each other, as well as with the lymphatic system of the stomach, liver, and neighboring organs. Regional lymph nodes of the first order are mainly the anterior and posterior pancreas.

duodenal duodenal nodes and nodes lying in the tail region along the splenic vessels. Second-order regional nodes are celiac nodes.

In the pancreas, three own nerve plexuses are distinguished: the anterior pancreas, the posterior and the lower. They lie in the surface layers of the parenchyma on the corresponding sides of the gland and represent a developed interlobular looped neural network. At the intersection of the loops of the superficial nervous network, there are nerve nodules, from which nerve fibers extend deep into the gland, penetrating into the interlobular connective tissue. Branching out, they surround the lobules of the gland and give branches to the ducts.

According to the histological structure, the pancreas is a complex tubular-alveolar gland. The glandular tissue consists of irregularly shaped lobules, the cells of which produce pancreatic juice, and of the accumulation of special round-shaped cells – islets of Langerhans that produce hormones. The glandular cells are conical in shape, contain a nucleus that divides the cell into two parts: a wide basal and a conical apical. After secretion of the secretion, the apical zone sharply decreases, the entire cell also decreases in volume and is well delimited from neighboring cells. When the cells are filled with secretions, their boundaries become unclear. The endocrine part of the gland makes up only 1% of the total tissue and is scattered in the form of separate islets in the parenchyma of the organ.

Based on the anatomical features of the pancreas, the following practical conclusions can be drawn:

1. The pancreas is closely connected with the surrounding organs, and above all with the duodenum, therefore, the pathological processes that occur in these organs cause changes in it.

2. Due to the deep bedding of the gland in the retroperitoneal space, it is inaccessible for examination by conventional methods, and the diagnosis of its diseases is difficult.

The complex relationships between the enzymes secreted by the gland, proenzymes, inhibitors, etc. sometimes cause an unexplored reaction, as a result of which self-digestion of the tissue of the pancreas and surrounding organs occurs, which is not amenable to drug correction.

3. Operations on the pancreas are associated with great difficulties due to its close contact with large arteries and veins; this limits the possibilities of surgical treatment and requires surgeons to have a good knowledge of the anatomy of this area.

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