Descending thoracic aorta
Segment · T4/T5 to T12 Posterior mediastinum Aortic hiatus T12
Runs from the arch at T4/T5 down the posterior mediastinum, first to the left of the vertebral column and then in front of it, to pass through the aortic hiatus of the diaphragm at T12. Branches are mostly segmental (posterior intercostals, subcostal) plus small visceral branches (bronchial, oesophageal, pericardial, mediastinal, superior phrenic).
Detail
- Level
- T4/T5 to the aortic hiatus at T12
- Branches
- Posterior intercostal 3–11, subcostal, bronchial, oesophageal, pericardial, mediastinal, superior phrenic
- Relations
- Oesophagus crosses in front of it from right to left; thoracic duct and azygos vein lie on its right
When it goes wrong
Coarctation of the aorta (narrowing at the isthmus just distal to the left subclavian, at the ligamentum arteriosum)
Upper-limb hypertension with weak, delayed femoral pulses (radio-femoral delay); blood reaches the lower body through internal thoracic → anterior intercostal → posterior intercostal collaterals, which enlarge and notch the inferior rib margins on chest X-ray; associated with bicuspid aortic valve and Turner syndrome
Stanford type B dissection
Tear begins just beyond the left subclavian origin and extends distally; a false lumen can occlude intercostal, renal or mesenteric ostia (paraplegia, AKI, mesenteric ischaemia); managed with blood-pressure control unless complicated
Practise this structure
3 questions in the bank tagged Thorax.
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