What is Pancreas?
The pancreas {pan = all; kreas = flesh) is a gland that is
partly exocrine and partly endocrine. The exocrine part
secretes the digestive pancreatic juice; and the endocrine
part secretes hormones, e.g., insulin. It is soft, lobulated
and elongated organ.
The pancreas is both an exocrine and an endocrine gland.
It is an elongated structure that lies on the posterior ab-
dominal wall behind the stomach and behind the peri-
toneum. It may be divided into a head, a neck, a body, and
a tail . The head is disc shaped and lies within
the concavity of the C-shaped duodenum. The uncinate
process is a projection to the left from the lower part of the
head behind the superior mesenteric vessels. The neck is
narrow and connects the head to the body; it lies in front
of the beginning of the portal vein. The body passes
upward and to the left across the midline, and the tail
extends to the hilus of the spleen in the splenicorenal
ligament.
Location Of Pancreas
The pancreas lies more or less transversely across the
posterior abdominal wall, at the level of first and second
lumbar vertebrae.
General Features
● In the adult, the pancreas is a retroperitoneal organ that measures 15 to 20 cm in length and weighs
about 85 to 120 g.
● The pancreas is both an exocrine gland and an endocrine gland.
● The pancreas consists of four parts as follows.
1. Head of the Pancreas
○ The head is the expanded part of the pancreas that lies in the concavity of the C-shaped curve of
the duodenum and is firmly attached to the descending and horizontal parts of the duodenum.
○ The uncinate process is a projection from the inferior portion of the pancreatic head.
○ The structures that lie posterior to the head of the pancreas are the IVC, right renal artery,
right renal vein, and the left renal vein.
2. Neck of the Pancreas
○ The structures that lie posterior to the neck of the pancreas are the confluence of the superior
mesenteric vein and splenic vein to form the portal vein.
3. Body of the Pancreas
○ The structures that lie posterior to the body of the pancreas are the aorta, superior mesen-
teric artery, left suprarenal gland, left kidney, renal artery, and renal vein.
4. Tail of the Pancreas
○ The tail of the pancreas is related to the splenic hilum and the left colic flexure.
Head of the Pancreas
Definition
Head is the enlarged flattened right end of the pancreas,
situated within the curve of the duodenum. 1
External Features
The head has three borders, superior, inferior and I right
lateral; two surfaces, anterior and posterior; I and one
process, called the uncinate process, which projects from
the lower and left part of the head towards the left.
Relations
Three Borders
The superior border is overlapped by the first part oi
pancreaticoduodenal artery . The infer*
border is related to the third part of the duodenui and
to the inferior pancreaticoduodenal artery. Tt right
lateral border is related to the second part off]
duodenum, the terminal part of the bile duct andt
anastomosis between the two pancreaticoduoder.
arteries
Two Surfaces
The anterior surface is related, from above downwari
to : (1) The gastroduodenal artery; (2) the transvei
to
colon, and (3) the jejunum which is separated from it
by peritoneum .
The posterior surface is related to : (1) The inferior
vena cava, (2) the terminal parts of the renal veins, (3)
the right crus of the diaphragm, and (4) the bile duct
which runs downwards and to the right and is often
embedded in the substance of pancreas '.
Uncinate 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 the pancreas
between its head and body. It is directed forwards,
upwards and to the left. It has two surfaces, anterior and
posterior
I Relations
The anterior surface is related to: (1) The peritoneum
covering the posterior wall of the lesser sac, and (2) the
pylorus . At its junction with the head there
lie the gastroduodenal and superior pancreaticoduodenal
arteries.
Spleen, Pancreas and Liver 285
The posterior surface is related to the termination of
the superior mesenteric vein and the beginning of the
portal vein .
Body of the Pancreas
Definition
The body of the pancreas is elongated. It extends from
its neck to the tail. It passes towards the left with a slight
upward and backward inclination.
External Features
It is triangular on cross-section, and has three borders
(anterior, superior and inferior). A part of the body
projects upwards beyond the rest of the superior border,
a little to the left of the neck. This projection is known as
the tuber omentale .
Relations
Three Borders
The anterior borderprovides attachment to the root of the
transverse mesocolon. The superior border is related to
coeliac trunk over the tuber omentale, the hepatic artery
to the right, and the splenic artery to the left. The inferior
border is related to the superior mesenteric vessels at its
right end .
Three Surfaces
The anterior surface is concave and is directed forwards
and upwards. It is covered by peritoneum, and is related
to the lesser sac and to the stomach. The posterior
surface is devoid of peritoneum, and is related to (1) the
aorta with the origin of the superior mesenteric artery,
(2) the left crus of the diaphragm, (3) the left suprarenal
gland, (4) the left kidney, (5) the left renal vessels, and
(6) the splenic vein .
The inferior surface i§ covered by peritoneum, and
is related to the duodenojejunal flexure, coils of jejunum
and the left colic flexure.
The tuber omentale projects upwards beyond the
lesser curvature of the stomach, and is related to the
lesser omentum across the lesser sac. It is the
relationship to the omentum that gives the process its
name.
Tail of the Pancreas
This is the narrow left end of the 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.
WHAT IS PANCREATIC DUCTS?
The main pancreatic duct opens into the second part of
the duodenum with the bile duct on the major duodenal
papilla . The main duct also sometimes drains sep-
arately into the duodenum. The accessory duct (if present)
drains the upper part of the head and opens into the duo-
denum on the minor duodenal papilla.
The exocrine pancreas is drained by two ducts, main and
accessory .
1. The main pancreatic duct of Wirsung lies near the
posterior surface of the pancreas and is recognised easily
by its 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.
BLOOD SUPPLY OF PANCREAS
Arteries
The pancreas is supplied : (1) Mainly by pancreatii
branches of the splenic artery, (2) the superioi
pancreaticoduodenal artery, and (3) the inferioi
pancreaticoduodenal 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.
The splenic artery and the superior and inferior pancreati-
coduodenal arteries supply the pancreas.
Veins
The pancreatic veins drain into the portal vein.
LYMPH DRAINAGE
The lymph nodes are situated along the arteries and drain
into the celiac and the superior mesenteric nodes.
NERVE SUPPLY
Sympathetic and parasympathetic vagal nerve fibers from
the celiac plexus supply the pancreas.
HISTOLOGY ~
1. The exocrine part is a serous gland, made up of
tubular acini lined by pyramidal cells with basal round
nuclei, containing zymogen granules. It secretes the
digestive pancreatic juice.
2. The endocrine part of the pancreas is made up of
microscopic elements called the pancreatic islets of
Langerhans. These are small isolated masses of cells
distributed throughout the pancreas. They are most
numerous in the tail. The islets have various types of
cells the most important of which are the betacells which
are granular and basophilic, forming about 80% of the
cell population. They produce insulin. Other types of
cells are alpha cells with subtype A1 and A2. These are
granular and acidophilic and form about 20% of the cell
population. Al cells belong to enterochromaffin group
and secrete pancreatic gastrin and serotonin. A2 cells
secrete glucagon.
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