In coarctation of aoa, the side of rib notching is
Superior to rib
Inferior to rib
At sternum
At veebra
Rib notching is unusual in infancy but becomes more frequent with increased age; it is present in 75% of adults with coarctation. Rib notching occurs along the inferior margin of the third to the eighth ribs; it is caused by pulsation of dilated intercostal aeries. Ref Davidson 23rd edition pg 443
C.V.S