Transcript Liver, biliary system, pancreas and spleen

Liver, biliary system,
pancreas and spleen
Long Nguyen
Embryology of the digestive glands
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Liver, gallbladder and pancreas develop from endodermal diverticulae that
bud from the duodenum in the 4th to 6th weeks
Liver sprouts first and expands in ventral mesentery
Cystic diverticulum also in ventral mesentery
Pancreas arises from a dorsal and ventral bud.
Ventral pancreatic bud migrates posteriorly to fuse with the dorsal bud.
Main duct of ventral bud becomes the main pancreatic duct.
Liver - exam questions
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Write short notes on the segmental
anatomy of the liver. (9/07, 9/05, 4/05,
9/04, 9/02)
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Write short notes on the arterial supply to
the liver and its normal variants. (9/08,
10/01)
Liver
Lies in right upper quadrant.
 Underlies the thoracic cage.
 Conforms to right dome of diaphragm
 Connected to the diaphragm by the
falciform and coronary ligaments
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Liver - relations
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Surfaces separated by
inferior border of liver and
coronary ligament
posteriorly
Bare area between the
reflections of coronary
ligaments in direct
contact with diaphragm
and not covered by
peritoneum
Diaphragmatic surface
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Smooth and convex
Separated from diaphragm
by subphrenic recess
Liver – relations (2)
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Visceral (posteroinferior) surface
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Lies in contact with oesophagus,
stomach and lesser omentum on
the left
Duodenum in midline
Right kidney, adrenal and hepatic
flexure of the colon on the right
H-shaped arrangement of
structures
Crossbar formed by porta hepatis
(portal vein, hepatic artery, hepatic
ducts, nerve plexus and lymph
vessels
Left: ligamentum teres (remnant of
left umbilical v.) and ligamentum
venosum (remnant of ductus
venosum)
Liver - old lobar anatomy
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Right and left lobes divided by plane through the IVC and gallbladder fossa on (Moore)
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Caudate lobe
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Lies posteriorly between lig. venosum and IVC fossa
Porta hepatis inferiorly
Tail-like caudate process connects to right lobe and separates portal vein from IVC
Quadrate lobe
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Anteroinferior between GB bed and lig. teres
Porta hepatis superiorly
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Caudate and quadrate lobe considered to be part of left lobe
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Reidel’s lobe (not a true lobe)
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Lower border of the right lobe lateral to the GB may project downwards for a considerable distance as a broad or bulbous process
Occurs in 5-10% of females and rarely in males
Liver - vascular anatomy
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Double blood supply from hepatic artery (30%) and portal vein (70%)
Arterial supply by common hepatic artery branch of coeliac artery.
Gives off right gastric and gastroduodenal arteries before reaching the liver
in the free edge of the lesser omentum.
Divides into left and right hepatic arteries before entering the liver at the
porta.
Variants of right hepatic artery below
Portal vein formed posterior to neck of pancreas by union of SMV and
splenic vein
Liver - vascular anatomy (2)
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Right and left lobes functionally independent and defined by arterial
distribution
Each supplied by left and right portal v., left or right hepatic arteries
and drained by left or right hepatic duct (portal triad)
Quadrate lobe supplied by left hepatic artery
Caudate lobe supplied by both
Liver - hepatic veins
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Hepatic veins are intersegmental and do not run with the
structures of the portal triad
Right, middle and left hepatic veins drain corresponding
thirds of the liver
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Middle hepatic vein lies in the principal plane between right and
left lobes
Left hepatic vein lies between medial and lateral segments of the
left lobe
Right hepatic vein lies between anterior and posterior segments
of the right lobe
All drain into the IVC without an extrahepatic course
Inferior group of small veins from right lobe also drains
into IVC
Liver - segmental anatomy
(Couinaud system)
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Knowledge of segments
important in the assessment of
location and extent of hepatic
pathology as surgery is
performed in segmental
fashion and distribution of
disease determines whether
lesions are resectable.
The hepatic veins divide the
liver into 4 divisions
A horizontal plane through the
portal vein divides the 4
divisions into superior and
inferior segments
Segments numbered in
clockwise direction starting at
caudate lobe (segment 1)
Liver – Lymph drainage and
innervation
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Lymph drainage
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Superficial and most deep lymph vessels converge at
the porta and end in the hepatic lymph nodes (eg.
Cystic LN near GB neck or LN of omental foramen)
Hepatic LN’s drain into coeliac LN’s around the
coeliac trunk, then thoracic duct
Some deep lymph vessels follow hepatic veins to IVC
foramen in diaphragm and end in middle phrenic LN’s
Innervation
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Sympathetic and parasympathetic supply from the
hepatic plexus, a derivative of coeliac plexus (formed
from fibres of left and right vagus and right phrenic
nerves)
Gallbladder and biliary tree – exam
questions
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Write short notes on the anatomy of the
gall bladder (9/04)
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Write short notes on the anatomy of the
biliary tree (excluding the gallbladder) and
normal variations (4/08, 9/07, 4/05)
Gallbladder and cystic duct
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Pear shaped sac lies to the right of
the quadrate lobe in GB fossa on
the visceral surface of liver
Concentrates and stores bile
secreted by the liver
Cholecystokinin produced by
intestinal mucosa during digestion,
passes to GB and causes it to
contract and release bile
Fundus, body and neck
Mucosal membrane arranged into
spiral folds (valves of Heister) at GB
neck and cystic duct
Gallbladder - relations
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Anterosuperiorly
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GB fossa of liver
Fundus projects from inferior border of liver, located
at tip of 9th costal cartilage in MCL where lateral edge
of rectus abdominis meets costal margin
Posteroinferiorly
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Neck: lesser omentum. Omental (epiploic) foramen
lies immediately to the left.
Body: D1
Fundus: transverse colon
Gallbladder – blood supply
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Arterial supply
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cystic artery
Venous drainage
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directly into liver or via a cystic vein
Biliary Tree
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Bile is secreted by hepatocytes into bile
canuliculi which drain into interlobular bile
ducts. Progressively larger ducts formed.
Left and right hepatic ducts emerge from
porta and merge to form common hepatic
duct (4cm)
Joined on the right by the cystic duct from
the GB to form the common bile duct (810cm long, 5-6mm diameter)
Runs in free edge of lesser omentum,
passes posterior to D1 and head of
pancreas
Comes in contact with pancreatic duct on
the left side of D2
Usually unite in the duodenal wall to form
hepatopancreatic ampulla (of Vater)
Ampulla opens into descending part of
duodenum at summit of major duodenal
papilla, 8-10cam from pylorus
Biliary Duct – blood supply
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Arterial supply
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Venous drainage
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Proximally: cystic artery
Middle: right hepatic artery
Distally: posterior superior pancreaticduodenal a.
Proximally: drainage directly into liver
Distally: posterior superior pancreaticduodenal v.
Lymph drainage
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Cystic LN, node of omental foramen, hepatic LN’s
Biliary Tree - variants
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Accessory hepatic ducts may
arise in the liver and join the right
hepatic duct, common hepatic
duct, common bile duct, cystic
duct or GB
Right and left hepatic ducts may
fail to unite giving a double duct
Cystic duct
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Absent
Joins common hepatic duct on the
left rather than the right
Joins the right hepatic duct or an
accessory duct
Joins the common hepatic duct
anywhere between the porta and
the duodenum (low and high
union)
Variants in union of CBD and
pancreatic duct
Pancreas – exam questions
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Write short notes on the anatomy of the
pancreatic ducts and variations. (9/08)
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Make brief notes on the embryology of the
pancreas. (10/00)
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What sonographic landmarks are useful in
identifying the pancreas? (10/00) Describe the
sonographic appearance of a normal pancreas.
Pancreas
Retroperitoneal organ lies transversely
and slightly obliquely at L1-L2 level
 Transverse mesocolon attached to anterior
margin
 Exocrine (pancreatic enzymes) and
endocrine functions (glucagon and insulin)
 Head, neck, body and tail
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Pancreas - Relations
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Head
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Neck
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Anterior to the union of splenic vein and SMV to form the portal vein
Body
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Lies in curvature of duodenum
Anterior to IVC, aorta, right renal vessels and left renal vein
Uncinate process projects posteriorly and to the left and lies posterior to
superior mesenteric vessels
CBD passes posteriorly in a groove or embedded within
Curves over vertebrae and great vessels
Anterior to the aorta and lies between the coeliac trunk and the SMA
Splenic vein passes posterior
Tail
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lies in the splenorenal ligament
Usually contacts the hilum of the spleen
Pancreas - Embryology
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Arises from the junction of the primitive foregut
and midgut as a larger dorsal division and a
smaller ventral bud
Ventral bud swings posteriorly to unite with the
inferior aspect of the dorsal bud trapping the
superior mesenteric between divisions
Ventral bud forms the uncinate process
Duct of the ventral bud forms the proximal end of
the main pancreatic duct; the distal end of the
dorsal pancreatic duct forms the remainder.
Pancreas - variations
Pancreas – blood supply
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Arterial supply
Head: superior pancreaticoduodenal a. (from
gastroduodenal artery) and inferior
pancreaticoduodenal a. (from SMA)
 Body and tail: branches from splenic artery
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Venous drainage
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Mostly splenic v., but also portal v. and SMV
Spleen
Large soft vascular lymphatic organ in the
left upper quadrant
 Up to 12cm with long axis in line with 10th
rib
 Arises from mass of mesenchymal cells
located between layers of dorsal
mesogastrium.
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Spleen - relations
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Posterior to stomach. Connected to greater curvature by
gastrosplenic ligament
Anterior to superior part of left kidney. Connected by
splenorenal ligament
Laterally: diaphragm, 9th-11th left ribs
Tail of pancreas lies at splenic hilum
Spleen – blood supply
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Arterial supply
Splenic artery divides into end arteries as it
enters the spleen
 No anastamoses, hence obstruction of one
end artery results in area of splenic infarction
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Venous drainage
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Splenic vein
Lymph drainage
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Pancreaticopsplenic LN’s