The fibrous cap is a layer of fibrous connective tissue, which is thicker and less cellular than the normal intima, found in atherosclerotic plaques. The fibrous cap contains macrophages and smooth muscle cells.^[1] The fibrous cap of an atheroma is composed of bundles of muscle cells, macrophages, foam cells, lymphocytes, collagen and elastin.^[1]

The fibrous cap is prone to rupture and ulceration which can lead to thrombosis. In advanced lesions, further complications may arise including calcification of the fibrous cap.^[2]