anatomy of pancreas

1. Pancreas anatomy and
physiology
Moderator : Dr Sahilu ( General and Hepatobiliary surgeon )
Dr Habtamu A. ( SR 1)

2. Contents
• Gross anatomy
• Vascular supply
• Pancreatic duct anatomy
• Neuroanatomy
• Physiology
• Investigation
• Summary of clinically significant points

3. • Retroperitoneal organ
• Weights 75 to 100 gm and is about 15 t0 20 cm long
• 4 regions
• It is an endodermally derived organ, consisting of two
morphologically distinct tissues, the exocrine and endocrine pancreas

4. Embryology

6. Head of pancreas
• The head of the pancreas is nestled in the C-loop of the duodenum
and is posterior to the transverse mesocolon.
• Just posterior to the head of the pancreas lie the vena cava, the right
renal artery and both renal veins
• The common bile duct runs in a deep groove on the posterior aspect
of the pancreatic head

10. Neck of pancreas
• The neck of the pancreas lies directly anterior to the portal vein.
• At the inferior border of the neck of the pancreas, the superior
mesenteric vein joins the splenic vein
• The neck of the pancreas is anterior to the vertebral body of L1 and
L2
• The neck divides the pancreas into approximately two equal halves.

11. Body and tail
• The body and tail of the pancreas lie just anterior to the splenic artery and
vein.
• The anterior surface of the body of the pancreas is covered by peritoneum.
• Once the gastrocolic omentum is divided, the body and tail of the pancreas
can be seen along the floor of the lesser sac, just posterior to the stomach
• The base of the transverse mesocolon attaches to the inferior margin of the
body and tail of the pancreas
• the tail is nestled in the hilum of the spleen near the splenic flexure of the
left colon

13. Pancreatic Duct Anatomy
• The duct of the ventral anlage becomes the duct of Wirsung, and the
duct from the dorsal anlage becomes the duct of Santorini.
• The ducts from each anlage usually fuse together in the pancreatic
head
• most of the pancreas drains through the duct of Wirsung, or main
pancreatic duct, into the common channel formed from the bile duct
and pancreatic duct.

14. • The length of the common channel is variable.
• In approximately 30% of patients, the duct of Santorini ends as a blind
accessory duct and does not empty into the duodenum
• main pancreatic duct is usually only 2 to 3 mm in diameter and runs
midway between the superior and inferior borders of the pancreas,
• Main pancreatic duct closer to the posterior than to the anterior
surface

15. • The muscle fibers around the ampulla form the sphincter of Oddi,
which controls the flow of pancreatic and biliary secretions into the
duodenum.
• Contraction and relaxation of the sphincter is regulated by complex
neural and hormonal factors.

17. Arterial supply

18. • The blood supply to the pancreas comes from multiple branches from
the celiac and superior mesenteric arteries
• The common hepatic artery gives rise to the gastroduodenal artery
• The gastroduodenal artery then travels inferiorly anterior to the neck
of the pancreas and posterior to the duodenal bulb.
• At the inferior border of the duodenum, the gastroduodenal artery
then gives rise to the right gastroepiploic artery then continues on as
the anterior superior pancreaticoduodenal artery

19. • superior mesenteric artery gives off inferior pancreaticoduodenal
artery .
• Variations in the arterial anatomy occur in one out of five patients.
• It is important to look for this variation on preoperative computed
tomographic (CT) scans and in the operating room
• The body and tail of the pancreas are supplied by multiple branches
of the splenic artery.
• The inferior pancreatic artery usually arises from the superior
mesenteric artery

22. Venous drainage
• The venous drainage of the pancreas follows a pattern similar to that
of the arterial supply (Fig. 33-5). The veins are usually superficial to
the arteries within the parenchyma of the pancreas.
• There is an anterior and posterior venous arcade within the head of
the pancreas.
• The superior veins drain directly into the portal vein just above the
neck of the pancreas.

24. • The posterior inferior arcade drains directly into the inferior
mesenteric vein.
• These venous tributaries must be divided during a Whipple procedure
• The anterior inferior pancreaticoduodenal vein joins the right
gastroepiploic vein and the middle colic vein.

25. • There also are numerous small venous branches coming from the
pancreatic parenchyma directly into the lateral and posterior aspect
of the portal vein.
• Venous return from the body and tail of the pancreas drains into the
splenic vein

27. Lymphatic drainage

28. • The profuse network of lymphatic drainage provides egress to tumor
cells arising from the pancreas.
• The pancreatic lymphatics also communicate with lymph nodes in the
transverse mesocolon and mesentery of the proximal jejunum.

29. Neuroanatomy
• The pancreas is innervated by the sympathetic and parasympathetic
nervous systems.
• The parasympathetic system stimulates endocrine and exocrine
secretion and the sympathetic system inhibits secretion.
• The pancreas also has a rich supply of afferent sensory fibers, which
are responsible for the intense pain

31. Physiology
• The exocrine pancreas accounts for about 85% of the pancreatic mass
• 10% of the gland is accounted for by extracellular matrix, and 4% by
blood vessels and the major ducts
• only 2% of the gland is comprised of endocrine tissue.
• regulates the type of digestion, its rate, and the processing and
distribution of absorbed nutrients.
• only approximately 20% of the normal pancreas is required to prevent
insufficiency

32. Exocrine pancreas
• patients can live without a pancreas when insulin and digestive enzyme
replacement are administered.
• The pancreas secretes approximately 500 to 800 mL per day of colourless ,
odourless , alkaline, isosmotic pancreatic juice.
• Pancreatic juice is a combination of acinar cell and duct cell secretions.

33. • The centroacinar and intercalated duct cells secrete the water and
electrolytes present in the pancreatic juice.
• About 40 acinar cells are arranged into a spherical unit called an
acinus.
• Centroacinar cells are located near the center of the acinus and are
responsible for fluid and electrolyte secretion.
• These cells contain the enzyme carbonic anhydrase, which is needed
for bicarbonate secretion.

36. • Secretin is the major stimulant for bicarbonate secretion
• CCK also stimulates bicarbonate secretion, but to a much lesser
extent than secretin.
• CCK potentiates secretin-stimulated bicarbonate secretion.
• Gastrin and acetylcholine, both stimulants of gastric acid secretion,
are also weak stimulants of pancreatic bicarbonate secretion.
• The endocrine pancreas also influences the adjacent exocrine
pancreatic secretions.

38. Endocrine pancreas
• There are nearly 1 million islets of Langerhans in the normal adult
pancreas
• Most islets contain 3000 to 4000 cells of five major types

40. Investigation
• Pancreatic function tests
• Estimation of pancreatic enzymes in body fluids
• Imaging
• Ultrasonography
• Computed tomography
• Magnetic resonance imaging
• Endoscopic retrograde cholangiopancreatography
• Endoscopic ultrasound

46. Summary (clinically significant )
• Plane between neck of pancreas and portal vein
• Splenic vein run in a groove on posterior side fed by multiple fragile
branches
• Window of wisnlsow connect the 2 sac in the abdomen
• Neck found at the L1 nd L2
• Gastroduodenal artery pass through duodenal bulb
• Head of pancreas and duodenum share significant vascular supply
• Islet cells have different distribution in pancreas
• Preoperative imaging is important to pick anatomic variant

47. References

48. THANK YOU