Citation, DOI & article data
The aortic knob or knuckle refers to the frontal chest x-ray appearance of the distal aortic arch as it curves posterolaterally to continue as the descending thoracic aorta. It appears as a laterally-projecting bulge, as the medial aspect of the aorta cannot be seen separate from the mediastinum. It forms the superior border of the left cardiomediastinal contour.
The aortic knob may become enlarged in:
- aortic dissection
- certain congenital heart diseases, e.g. patent ductus arteriosus, truncus arteriosus, valvular insufficiency, severe tetralogy of Fallot
- post-stenotic dilatation
- systemic hypertension
- thoracic aortic aneurysm
- traumatic aortic injury
The aortic knob may be small or absent in:
The aortic knob may be obscured by:
- 1. Shankar, Nachiket, et al. "Anatomical variations of the aortic knob in chest radiographs." Eur J Anat 14.1 (2010): 25-30.
- 2. Lawrence Roger Goodman. Felson's Principles of Chest Roentgenology. (2018) ISBN: 9781455774838