A 22-year-old man presents with hypertension of the upper limbs, radiofemoral delay, and a chest radiograph showing bilateral notching of the lower borders of the 3rd to 8th ribs. Which collateral pathway explains this radiographic sign?
- A Enlarged anterior intercostal arteries feeding dilated posterior intercostal arteries
- B Dilated bronchial arteries eroding the rib cortex
- C Dilated posterior intercostal arteries fed by the internal thoracic artery via the anterior intercostal arteries ✓
- D Enlarged superior epigastric arteries notching the ribs directly
Correct answer: C. Dilated posterior intercostal arteries fed by the internal thoracic artery via the anterior intercostal arteries
Explanation
In coarctation of the aorta distal to the origin of the left subclavian artery, blood reaches the descending aorta through enlarged internal thoracic arteries, whose anterior intercostal branches anastomose with the posterior intercostal arteries. These dilated, tortuous posterior intercostal arteries press on the inferior surface of the ribs, producing the classic notching. Bronchial arteries do not contact the rib cage, and the direction of flow in option A is reversed.
Reference: Gray's Anatomy for Students, 4th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.