Anatomy — Thorax and Abdomen: Surface Anatomy, NMC MBBS licence examination syllabus (Nepal Medical Council).
Anatomy earns its place in a clinical exam when it explains something at the bedside — why the pain is where it is, and why the needle goes where it goes.
The first two anatomy chapters covered the limbs and the head. This one covers the trunk, and it is organised around four things that anatomy explains and nothing else does.
Each rib carries a groove along its lower border, and in that groove run the vein, the artery and the nerve — in that order from the top down. The bone protects them, which is a good arrangement until someone puts a needle through the chest wall.
The rule that follows: enter just above the rib below, not below the rib above. The upper border of a rib is bone; the lower border is where the vessels sit. Every pleural procedure rests on this, and it is the reason the site is described in relation to a rib rather than to a measurement.NMCSU02 covers the procedures themselves. What matters here is that the anatomy explains the instruction, so it is remembered as a reason rather than a rule.
The diaphragm develops in the neck and descends, dragging its nerve supply with it. That nerve therefore comes from segments high in the neck — the same segments that supply the skin over the shoulder tip.
The clinical consequence is one of the most useful pieces of referred anatomy: irritation under the diaphragm is felt at the shoulder. Blood from a ruptured spleen, pus from a perforation, or blood from a ruptured ectopic pregnancy can all present with shoulder-tip pain.
Dividing the abdomen into regions is only useful if it maps to structures. The three worth carrying:
Right upper — liver, gallbladder, bile ducts and duodenum. Also the right lung base, which is why a lower lobe pneumonia can present as upper abdominal pain, particularly in a child.
Epigastrium — stomach, pancreas and aorta. And the heart: an inferior myocardial infarction is commonly felt here, which is why epigastric pain in an older patient deserves an ECG before an antacid. NMCMD01 covers that presentation.
Right lower — appendix, caecum, ovary and ureter. In a woman of reproductive age, pregnancy is considered before any other diagnosis, because the one that kills quickly is ectopic.
The classical history of appendicitis is not a list of symptoms — it is a sequence, and the sequence is anatomical.
Early, the inflamed appendix produces pain through the gut's own nerve supply, which is poorly localised. The patient reports vague central pain they cannot point to.
Later, the inflammation reaches the lining of the abdominal wall, which is supplied by nerves that localise precisely. The pain becomes sharp and the patient can indicate it with one finger.
Which is why the useful question is "where did the pain start?" rather than only "where is it now". Pain that began centrally and moved to the right iliac fossa is a specific story that few other conditions tell.A man is stabbed below the left nipple and is shocked. That is an abdominal injury as much as a chest one — the diaphragm rises high, and the spleen sits beneath the ribs.
A woman has severe left shoulder pain; the shoulder moves freely and is not tender. Examine the abdomen and check a pregnancy test. Diaphragmatic irritation is referred to the shoulder tip, and a ruptured ectopic bleeds into that space.
A 60-year-old has epigastric pain and feels sweaty. An ECG comes before a diagnosis of indigestion. The epigastrium is where an inferior infarct is felt.
A teenager has had vague central abdominal pain since morning that is now sharp in the right iliac fossa. The migration is the diagnosis; that pattern is appendicitis until proven otherwise.
Chest and abdomen as separate boxes. The diaphragm domes upward, so the upper abdomen lies behind the lower ribs. Injuries and infections cross freely between them.
Where the pain is now and where it began. The migration carries more diagnostic weight than the current site.
Shoulder pain and shoulder disease. A normal shoulder examination in a patient with shoulder pain is a finding, not a reassurance.
Vein, artery, nerve run in the groove under each rib — so a needle enters just above the rib below.
The diaphragm's nerve supply comes from the neck — so subdiaphragmatic irritation is felt at the shoulder tip.
Epigastric pain in an older patient — ECG before antacid.
Right iliac fossa pain in a woman of reproductive age — pregnancy test first.
Central pain that moves and localises — the appendicitis sequence, and an anatomical explanation rather than a memorised fact.
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