MRCS PART A · APPLIED BASIC SCIENCES
Duodenum, pancreas & portal-vein relations
Localise the segment before naming its neighbour. Build a spatial model, then change one finding and test whether your answer still fits. Two selected objectives with four original applied-anatomy questions; not a procedural guide.
2 topics · 4 original SBAs
1 · Duodenal segments: different neighbours, different consequences
Your task: Distinguish retroduodenal arterial relations from the aortomesenteric crossing.
What lies behind the first part?
The gastroduodenal artery is an important posterior relation. The bile duct and portal vein also lie posteriorly in this region; an arterial question and a ductal question are not interchangeable.
Why does a posterior ulcer change the anatomical concern?
Penetration may reach the gastroduodenal artery and cause bleeding. This explains a structural relationship, not a complete haemorrhage-treatment plan.
Does every bleeding ulcer prove this vessel was injured?
No. The relationship predicts a plausible source; identifying an individual bleeding source requires assessment. Do not turn an anatomy association into diagnostic certainty.
Which part lies between the SMA anteriorly and aorta posteriorly?
The horizontal third part. Reduced space in this aortomesenteric relationship can produce extrinsic duodenal compression.
Does a narrow angle alone establish the cause of vomiting?
No. A spatial observation needs compatible clinical and imaging findings. This lesson does not provide a diagnostic threshold or management protocol.
Where do the usual bile and main pancreatic duct outlets meet the bowel?
They commonly unite at the hepatopancreatic ampulla opening at the major papilla in the second part of the duodenum. Ductal arrangements vary.
What if the question concerns the third part instead?
Do not transfer the papilla landmark to a different segment. Ask whether the question is about a duct outlet, a vessel crossing or the segment's supply.
2 · Behind the pancreatic neck, in front of the uncinate process
Your task: Trace venous confluence and distinguish pancreatic from hepatoduodenal relationships.
Where is the usual portal-vein confluence?
The splenic vein and superior mesenteric vein unite behind the pancreatic neck. Follow the vessel, rather than identifying it from one isolated image.
Is the inferior mesenteric vein an obligatory third vessel at this junction?
No. Its termination varies. The standard named confluence is splenic vein plus SMV; variation should be described, not forced into a fixed three-way junction.
Is every part of the pancreas anterior to the superior mesenteric vessels?
No. The neck overlies the venous confluence, but the uncinate process extends posterior to the superior mesenteric vessels in the usual arrangement.
Why does this matter when labelling a cross-section?
A pancreatic extension behind these vessels can be the uncinate process. 'Pancreas anterior to vessels' is an incomplete rule; localise the pancreatic part first.
Where does the portal vein travel next?
It ascends towards the liver within the hepatoduodenal ligament, posterior to the bile duct and proper hepatic artery in conventional anatomy.
Which vein must not be confused with it?
Hepatic veins drain from the liver towards the IVC. They are not the portal inflow vessel within the ligament. Inflow and outflow must be traced separately.