A 19-year-old man has radiofemoral delay and hypertension in the upper limbs. Chest radiograph shows bilateral inferior rib notching. Which collateral pathway explains this radiographic sign?

• A Thoracoacromial arteries connecting to the musculophrenic arteries
• B Superior epigastric arteries connecting to the bronchial arteries
• C Lateral thoracic arteries connecting to the supreme intercostal artery
• D Internal thoracic arteries connecting to posterior intercostal arteries via anterior intercostal branches ✓

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. Dilated, tortuous posterior intercostal arteries erode the inferior surface of the ribs, producing notching. This collateral circuit spares the first two interspaces because the first two posterior intercostal arteries arise proximal to the obstruction from the costocervical trunk.

Reference: Gray's Anatomy for Students, 4th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.