PANCREAS

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Features

The pancreas is a gland that is partly exocrine and partly endocrine.
The exocrine part secretes the digestive pancreatic juice and the endocrine part secretes harmones e.g insulin .
It is soft , lobulated and elongated organ.

Location

The pancreas lies more or less transversely across the posterior abdominal wall, at the level of first and second lumbar vertebrae.

Size and shape 

It is J - shaped  or retort shaped . The bowl of the retort represents it's head and the stem of retort it's neck, body and tail.
It's length is about 15 -20 cm long.
It is 2.5 - 3.8 cm broad.
It's thickness is about 1.2-1.8cm.
It weighs about 90gm.

The pancreas is divided ( from right to left ) into head, neck,body and tail.
The head is enlarged and lies within the concavity of the duodenum. 
The tail reaches the hilum of spleen.
       
The entire organ lies posterior to the stomach separated from it by the lesser sac.

Head of the Pancreas

Head of the Pancreas is enlarged flattened right end of Pancreas, situated within the ' C- shaped' curve of the duodenum.

External features

The head has three borders - superior, inferior and right lateral.
 Two surfaces - Anterior and posterior
 One process - unicate process  which projects from the lower and left part of the head towards the left .

Unicate process

It is related anteriorly to the superior mesenteric vessels and posteriorly to the aorta.

Neck of the Pancreas

This is the slightly constricted part of Pancreas between it's head and body.
It is directed forwards , upwards and to the left.
It has two surfaces - anterior and posterior .

Body of the Pancreas

The body of the Pancreas is elongated. It extends from it's neck to the tail.
It passes towards the left with a slight upward and backward inclination.

External features

It is triangular in cross section and has three borders - 1) Anterior
                             2) superior
                            3) Inferior.

A part of the body projects upward beyond the rest of the superior border, a little to the left of the neck. This projecttion is known as tuber omentale.


Tail of the Pancreas

This is the left end of Pancreas. It lies in the lienorenal ligament together with the splenic vessels. It comes into contact with the lower part of the gastric surface of the spleen.

Ducts of the Pancreas

The exocrine pancreas is drained by two ducts, main and accessory ducts.
 The main pancreatic duct of wirsung lies near the posterior surface of the Pancreas and is recognised easily by it's white colour.
It begins at the tail ; runs towards the right through the body; and bends at the neck to run downwards backwards and to the right in the head.
It's lumen is about 3 mm in diameter.
It receives many small tributaries which join it at right angles to it's long axis forming what has been described as a heiring bone pattern.

With the head of the Pancreas the pancreatic duct is related to the bile duct which lies on it's right side.
                                               The two ducts enter the wall of the second part of duodenum,and join to form the hepatopancreatic ampulla of vater which opens by a narrow mouth on the summit of the major duodenal papilla, 8-10cm distal to the pylorus.

The accessory pancreatic duct of santorini begins in the lower part of the head, crosses the front of main duct with which it communicates and opens into the duodenum at the minor  duodenal papilla.
            The papilla of accessory pancreatic duct is situated 6 to 8 cm distal to pylorus.
The opening of the accessory duct lies cranial and ventral to that of the main duct.
The two ducts remind the double origin of Pancreas from the ventral and dorsal pancreatic buds.

Arterial supply

The pancreas is supplied by : 
1. Mainly by pancreatic branches of the splenic artery
2. The superior pancreatoduodenal artery
3. The inferior pancreatoduodenal artery
   
Like the duodenum the Pancreas develops at the junction of the foregut and midgut and is supplied by branches derived from both the coeliac and superior mesenteric arteries.

Venous drainage

Veins drain into splenic , superior mesenteric and portal vein.

Lymphatic drainage

Lymphatics follow the arteries and drain into the pancreatosplenic ,coeliac and superior mesenteric groups of lymph nodes.

Nerve supply

The vagus or parasympathetic and splanchnic sympathetic nerves supply the Pancreas through the plexuses around it's arteries.

Functions

Digestive - Amylase hydrolyses the starch and glycogen into disaccharide.
Trypsin breaks the protein into lower peptides. Lipase breaks fat into fatty acids .

Endocrine - carbohydrates are immediate source of energy. Insulin helps in utilisation of sugar in the cells. Deficiency of insulin results in hyperglycemia. This disease is called as diabetes mellitus.

Pancreatic juice - it provides alkaline medium (pH 8) for the activity of pancreatic enzymes.







                                 By Vijay Kumar Singh

                                        BAMS (student)

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