Accessory Organs - Pancreas

Question 1

Anatomical position?

Answer 1

Located at the level of the transpyloric plane at the level of L1.

With the exception of the tail, it is a retroperiteoneal organ, located within the epigastrium and left hypochondrium.

It has direct connections with several other organs:

1) Stomach - separated from the pancreas by the lesser sac, The stomach and pylorus lies anterior to the pancreas.
2) Duodenum - The ‘c’ shaped duodenum surrounds the head of the pancreas. The first part of the duodenum lies anteriorly, whereas the second part lies laterally to the right of the head of the pancreas.
3) Transverse mesocolon - attaches to anterior surface of the pancreas.
4) Common bile duct - descends behind the head of the pancreas before opening into the second part of the duodenum alongside the major pancreatic duct through the major duodenal papilla.
5) Spleen - located posteriorly and laterally. The lienorenal ligament is formed from the peritoneum and connects the spleen to the pancreas.

It is also connected to several vessels:

1) Aorta/IVC - lies posteriorly to the head of the pancreas.
2) Superior mesenteric artery - lies behind the neck of the pancreas and anterior to the uncinate process.
3) Splenic and superior mesenteric veins unite to form the hepatic portal vein - posterior to the neck of the pancreas.
4) Splenic artery - from the coeliac plexus to the splenic hilum, it traverses the superior border of the pancreas.

Question 2

Anatomical structure?

Answer 2

It can be divided into five parts:

1) Head - the widest part of the pancreas. It lies within the ‘c’ shaped duodenum and is connected to it by connective tissue.
2) Uncinate process - a projection arising from the lower part of the head and extending medially to lie beneath the body of the pancreas. It lies posterior to the superior mesenteric vessels.
3) Neck - located between the body and the head of the pancreas. It overlies the superior mesenterior vessels which form a groove in its posterior aspect.
4) Body - centrally located, crossing the midline of the human body to lies behind the stomach and the the left of the superior mesenteric vessels.
5) Tail - the left end of the pancreas that lies within close proximity to the hilum of the spleen. It is contained within the splenorenal ligament with the splenic vessels. This is the only part of pancreas that is intraperitoneal.

Question 3

Duct system

Answer 3

The exocrine pancreas is classified as a lobulated serous gland which produces digestive enzyme precursors.

It is composed of approximately one milllion ‘berry-like’ clusters of cells called acini, connected by short intercalated ducts.

The intercalated ducts unite with those draining adjacent lobules and drain into a network of intralobular collecting ducts, which in turn drain into the main pancreatic duct.

The pancreatic duct connects runs the whole length of the pancreas and unites with the common bile duct, forming the hepatopancreatic ampulla of Vater. This structure then opens into the duodenum via the major duodenal papilla.

Secretions into the duodenumare controlled by a muscular valve - the sphincter of Oddi. It surrounds the ampulla of Vater, acting as a valve.

Question 4

Vasculature?

Answer 4

The pancreas is supplied by branches of the splenic artery.

The head is also supplied with superior and inferior pancreaticoduodenal arteriesm, which branches of the gastroduodenal (from the coeliac trunk) and superior mesenteric arteries, respectively.

Venous drainage of head of the pancreas - superior mesenteric branches of the hepatic portal vein.

The pancreatic and splenic veins drain the rest of the pancreas.

Question 5

Lymphatics

Answer 5

The pancreas is drained by lymphatic vessels that follow the arterial supply. They empty into the pancreaticosplenal nodes and the pyloric nodes, which in turn into the superior mesenteric and the coeliac lymph nodes.

Question 6

Clinical relevance - pancreatitis

Answer 6

This is inflammation of the pancreas. This can be acute or can persist over an extended period of time.

The causes of the pancreatitis can be remembered using the mnemonic - GET SMASHED:

G - Gall stones

E - Ethanol

T - Trauma

S - Steroids

M - Mumps

A - Autoimmune

S - Scorpion stings

H - Hypertriglyceridemia, hypercalcaemia and hyperparathyroidism

E - ERCP - endoscopic retrograde cholangiopancreatography

D - Drugs - sodium valproate, azathioprine, and sulphanomides

Pancreatitis causes severe epigastric pain which often radiates to the back, nausea, vomiting and diarrhoea.

Treatment involves supportive measures such as IV fluids and analgesia. Antibiotics are rarely required, as most cases are not due to infection. The underlying cause will then also need to be treated.`