aortic knuckle

a·or·tic knuck·le

the contour of the aortic arch protruding from the mediastinal silhouette in an anteroposterior (AP) radiograph of the chest.
References in periodicals archive ?
Along with cardiomegaly, X-ray chest shows rib notching and prominent aortic knuckle with thoracic indentation, while narrowing of isthumus is seen on Echocardiography.
X ray chest- Kyphoscoliosis deformity present CTR>50% LV apex, Aortic Knuckle prominent Pulmonary conus prominent pulmonary plethora present.
The foreshortened distal most portion of the aortic arch where it joins the descending aorta represents the aortic knob or aortic knuckle and it constitutes the superior most part of the left border of the cardiac silhouette.
REVIEW OF LITERATURES: Although the Postero-anterior chest X-ray is one of the most commonly done investigations in outdoor practice, there is paucity of data regarding the width of aortic knuckle (AK).
One of the land marks of the X-ray plate of chest X-ray is the aortic knob or aortic knuckle to note if there any deformity or enlargement of the said knob is present or not.