Where do aneurysms typically form in cases of Fibromuscular Dysplasia?

Aneurysms associated with Fibromuscular Dysplasia (FMD) typically occur at points of arterial bifurcation. FMD leads to abnormal growth in the layers of blood vessels, which often results in stenosis, aneurysm, or dissection of the affected arteries. The most significant manifestation of FMD in terms of aneurysm formation is usually seen at the bifurcations, particularly in the renal and carotid arteries.

This preference for the bifurcation is attributed to the hemodynamic factors and changes in flow dynamics associated with areas where arterial branches split. At these bifurcations, there is an increased turbulence and shear stress on the vessel walls, which contributes to the development of aneurysms.

The other options, such as the aortic arch, distal, or proximal ends of the arteries, do not typically exhibit aneurysm formation related to FMD as prominently as the bifurcations do, which explains why the correct answer focuses specifically on those areas where the arteries divide.