Anatomy 14 Flashcards
Where does the coeliac trunk leave the anterior aspect of the aorta?
At the level of T12
What major branches does the coeliac trunk give rise to?
- The left gastric artery – supplies the distal oesophagus and lesser curvature of the stomach.
- The common hepatic artery – branches supply the liver, stomach, and duodenum.
- The splenic artery – branches supply the stomach, pancreas, and spleen.
What is the duodenum?
First and shortest part of the small intestine
What is the duodenum continuous with?
Continuous proximally with the pylorus of the stomach and distally with the jejunum
What is the function of the pyloric sphincter?
Regulates gastric emptying into the duodenum
Describe features of the duodenum?
- Most of the duodenum is retroperitoneal
- The duodenum forms a C-shape that cups the head of the pancreas
What are the 4 parts of the duodenum?
Superior (first)
Descending (second)
Inferior (third)
Ascending (fourth)
What lies posterior to the first part of the duodenum?
Bile duct
Gastroduodenal artery
Hepatic Portal Vein
Where is the superior mesenteric artery located in relevance to the duodenum?
Lies anterior to the 3rd part of the duodenum
What does the 4th part of the duodenum meet?
Meets the jejunum at the duodenojejunal flexure
What is the major duodenal papilla?
Approximately halfway along the internal wall of the duodenum is a small elevation
This marks the point at which bile and digestive pancreatic secretions (‘pancreatic juice’) enter the duodenum
What is the 1st half of the duodenum derived from?
Foregut
What is the 1st half of the duodenum supplied by?
Branches of the coeliac trunk (the artery of the foregut)
What is the 2nd half of the duodenum derived from?
Midgut
What is the 2nd half of the duodenum supplied by?
Branches of the superior mesenteric artery (the artery of the midgut)
What are arterial branches that supply the duodenum derived from?
- Gastroduodenal artery (from the common hepatic artery and hence the coeliac trunk)
- Inferior pancreaticoduodenal arteries (from the superior mesenteric artery)
Veins follow the arteries and are tributaries of the hepatic portal vein
Where is the pancreas located?
Lies horizontally on the posterior abdominal wall at the level of L1
Describe features of the pancreas
Retroperitoneal
It does not have a capsule so in the cadaver its surface appears ‘bumpy’ rather than smooth
What is the pancreas formed from?
From dorsal and ventral pancreatic buds which fuse during development
What are the 4 parts that the pancreas is composed of?
Head
Neck
Body
Tail
What is the uncinate process?
Hook-like projection of the head of the pancreas
What is the head of the pancreas cupped by?
Cupped by the C-shaped duodenum and the tail extends to the hilum of the spleen
What does the pancreas form part of?
Forms part of the posterior wall of the lesser sac
What does the splenic artery run towards?
Runs towards the spleen embedded in the upper border of the pancreas
Where is the splenic vein located?
Lies posterior to the pancreas
What do the main pancreatic duct and the accessory pancreatic duct run within?
Substance of the pancreas
What is the function of the pancreas?
It synthesises and secretes insulin and glucagon
The pancreas also produces pancreatic juice that contains digestive enzymes
Where is pancreatic juice transported?
Transported through main pancreatic duct and the accessory pancreatic duct to the duodenum.
The main and accessory pancreatic ducts usually communicate with each other
What does the duodenum receive?
- bile from the liver and gallbladder via the bile duct
- pancreatic juice from the pancreas via the main and accessory pancreatic ducts
Where do the bile duct and main pancreatic duct merge?
At the hepatopancreatic ampulla (ampulla = dilation)
What does the hepatopancreatic ampulla open into?
The second part of the duodenum at the major duodenal papilla, which is located on the internal wall of the duodenum, about halfway along its length
What type of muscle is the hepatopancreatic ampulla surrounded by?
Smooth muscle - the sphincter of Oddi.
Contraction of the sphincter prevents reflux of duodenal contents into the bile and main pancreatic ducts
What is the function of the accessory pancreatic duct?
Empties pancreatic juice into the duodenum at the minor duodenal papilla, which lies just proximal to the major duodenal papilla
What blood vessels is the pancreas supplied by?
Supplied by blood vessels derived from the coeliac trunk and blood vessels derived from the superior mesenteric artery:
- The splenic artery, a major branch from the coeliac trunk, runs along the upper border of the pancreas and gives rise to pancreatic arteries.
- The gastroduodenal artery (from the common hepatic artery and hence the coeliac trunk) gives rise to the superior pancreaticoduodenal arteries that supply the pancreas.
- The superior mesenteric artery gives rise to the inferior
pancreaticoduodenal arteries that supply the pancreas.
What vein drains the pancreas?
Splenic vein, unites with the superior mesenteric vein to form the hepatic portal vein posterior to the neck of the pancreas
What is the spleen?
Haematopoietic and lymphoid organ
Where is the spleen located?
Lies in the left upper quadrant, protected by ribs 9 - 11
What is the spleen covered by?
Visceral peritoneum
What are functions of the spleen?
Breakdown of old red blood cells
The storage of red blood cells and platelets
Various immune responses, including production of IgG
What are the two surfaces of the spleen?
- the diaphragmatic surface lies adjacent to the diaphragm
- the visceral surface lies in contact with the stomach, left kidney and colon
Where do the splenic vessels enter and exit the spleen?
At the hilum on the visceral surface
Describe the feature of the anterior and superior borders of the spleen
Typically notched
Describe the feature of the posterior and inferior borders of the spleen
Smooth
Is a normal sized spleen palpable?
A normal sized spleen is not palpable below the costal margin.
If it is palpable, it is enlarged by at least three times its normal size
What is the spleen supplied by?
Splenic artery, a branch of the coeliac trunk
Where does the splenic artery run?
Runs along the superior border of the pancreas,
embedded within it.
The artery divides into approximately five branches at the hilum
What drains the spleen?
Venous drainage is via the splenic vein, which runs posterior to the pancreas.
It unites with the superior mesenteric vein to form the hepatic portal vein.
What is a duodenal ulcer?
Duodenal (peptic) ulcers are most common in the first part of the duodenum.
A duodenal ulcer here may erode the duodenal wall and the gastroduodenal artery, which lies posterior to the first part of the duodenum, resulting in severe intraabdominal bleeding
What is pancreatitis?
Inflammation of the pancreas may be chronic or acute.
Acute pancreatitis is a lifethreatening condition.
There are many causes, but in the UK, it is most commonly
due to excess alcohol intake or impaction of a gallstone at the hepatopancreatic ampulla.
In gallstone pancreatitis, impaction of the gallstone prevents pancreatic juice from leaving the pancreas and it starts to break down the pancreas (autolysis).
What is pancreatic cancer?
Pancreatic cancer can affect any part of the pancreas and typically causes pain that radiates to the back.
When it affects the head of the pancreas, it can obstruct flow of
bile in the bile duct.
This leads to an accumulation of bile pigments in the blood and
results in jaundice (yellowing of the skin).
What is diabetes mellitus?
Diabetes mellitus results when the insulin-producing cells of the pancreas no longer produce insulin (or produce inadequate amounts).
This leads to sustained high blood glucose levels which are detrimental to many tissues of the body and are ultimately fatal if not controlled.
Some patients develop diabetes secondary to pancreatitis
What is splenomegaly?
Enlargement of the spleen is splenomegaly.
Causes include infection (e.g. infectious mononucleosis, malaria), haematological malignancy (e.g. leukaemia) and portal
hypertension.
When the spleen enlarges, it does so towards the midline, in the
direction of the right iliac fossa, because the phrenicocolic ligament prevents its direct descent towards the left iliac fossa.
What is splenic rupture?
The spleen is soft and highly vascular and is therefore vulnerable to blunt abdominal trauma or rib fractures that may puncture the spleen.
Splenic haemorrhage is lifethreatening and is managed by removing the spleen (splenectomy).
The spleen is not essential for life, although patients are more prone to some bacterial infections after splenectomy
