Pancreas

Pancreas


PANCREAS

  • Mixed gland, consisting of both exocrine and endocrine parts with very little connective tissue.
  • Extends across the posterior abdominal wall from the concavity of duodenum to the hilum of spleen.
  • It occupies the posterior part of epigastrium and left hypochondrium.
  • From right to left the pancreas presents head, neck, body and tail. 

Head

  • It is the brodest and thickest part that lie within the curve of duodenum.
  • Most common site for carcinoma of pancreas.
  • Its relations are :
  1. Anterior : First part of duodenum  tranverse mesocolon, peritoneum of jejunal loops.
  2. Posterior : IVC, terminal part of right renal vein, right crus of dlaphragm,common bile duct.
  3. Superior : lst part of duodenum, superior pancreaticoduodenal artery.
  4. Duodenal (right lateral) :- 2d part of duodenum, terminal bile duct, anastomosis between superior and inferior pancreaticoduodenal artery.
  5. Inferior:– 3rd part of duodenum, inferior pancreaticoduodenal artey. 
  • Uncinate process: is the part of head that extends to the left from its inferior and behind superior mesenteric relations vessels. 
  • Its relations are :
  1. Anterior: Superior mesenteric veinoccasionally superior mesenteric artery.
  2. Posterior : Aorta
  3. Inferior: Upper surface of 3.rd part of duodenum.

Neck

  • Boundary between head and neck is marked :
  1. anteriorly by groove for gastroduodenal artery and
  2. posteriorly by deep groove that contains union of superior mesenteric vein and splenic, vein to form portal vein
  • Gastroduodenal and anterior superior pancreaticoduodenal arteries descend in front ofpancreas at the junction of head and neck.
  • Neck is related anteriorly to lesser sac and pylorus and posteriorly to origin of portal vein by union of Superior mesenteric vein and splenic vein.

Body

  • It is the longest portion of pancreas and has triangular cross section with three borders and three surfaces. Their relations are :-
  • Anterior border provides attachment to the root of transverse mesocolon.
  • Superior border is related to celiac trunk, hepatic artery and splenic artery.
  • Inferior border is related to superior mesenteric vessels.
  • Anterior surface is covered with peritoneum and is related to lesser sac and stomach.
  • Posterior surface is devoid of peritoneum and is related to structures forming pancreatic bed: aorta with origin of superior mesenteric artery, left crus of diaphragm, left kidney, left suprarenal gland, left renal vessels and splenic vein.
  • Inferior surface is covered by peritoneum and is related to duodenojejunal flexure, coils of jejunum and left colic flexure.

Tail

  • It is the narrowest portion of pancreas and lies in layers of splenorenal ligament.
  • It is related anteriorly to Iesser sac, posteriorly inferomedial part of spleen and splenic vessels and below to left colic flexure.
  • Tail of pancreas contains maximum number of Islet of Langerhans. 

Development

  • Pancreas is developed from the two pancreatic buds.

Dorsal Pancreatic bud

  • Larger and most of the pancreas is derived from it i.e. most of the head, and whole neck, body & tail

Ventral Pancreatic bud

  • Smaller and forms lower part of the head of pancreas including uncinate process. 
  • During 7th week of development, the ventral and dorsal pancreatic buds fuse to form a single pancreatic mass.
  • After the fusion of ventral and dorsal pancreatic buds, their ducts develop cross communications.
  • Final duct system is formed as below –

Main pancreatic duct (Duct of wirsung) is formed by the duct of ventral bud, distal part of duct of dorsal bud and an oblique communication between the two.

  • The main pancreatic duct join the bile duct to form hepatopancreatic ampulla that enters the 2nd part of duodenum at major duodenal papilla. 

Accessory pancreatic duct is formed by the proximal part of the duct of dorsal bud.

  • It opens into 2″d part of duodenum at minor duodenal pupilla, 2cm proximal (cranial) to major duodenal papilla. 

Anomalies of pancreatic development

1.  Annular pancreas:

  • Two components of the ventral bud fail to fuse and grow in oppsite direction arround the duodenum and meet the dorsal pancreatic duct. 
  • Treatment of choice for annular pancreas is Duodenojejunostomy.

2. Pancreatic divisum (divided pancreas) :

  • Ventral and dorsal buds fail to fuse with each other
  • It is the most common congenital anomaly of Pancreas.

3. Inversion of pancreatic duct :

  • The main pancreatic duct is formed by the duct of dorsal bud, i.e. accessory duct is larger than the main duct and the main drainage of pancreas is through the minor duodenal papilla. 

4. Accessory pancreatic tissue-  May be found in –

  1. Wall of stomach, duodenum, jejunum or ileum.
  2. Meckel’s diverticulum.
Exam Question
 
  • Posterior relation of neck of pancreas is Origin of portal vein.
  • Annular pancreas is a congenital anamoly resulting from failure of normal clockwise rotation of the ventral pancreas. The histology of pancreatic tissue is normal.
  • Treatment of choice for annular pancreas is Duodenojejunostomy.
  • Most common site for carcinoma of pancreas is Head.
  • The posterior relations of the head of the pancreas include the common bile duct, inferior vena cava and the right and left renal veins terminating into it. 
  • The first part of the duodenum is an anterior relation of the head of the pancreas.
  • Tail of pancreas contains maximum number of Islet of Langerhans.
  • Glucagonomas are usually large tumors at diagnosis. 50–80% occur in the pancreatic tail
Don’t Forget to Solve all the previous Year Question asked on Pancreas

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