What layer of the aorta is affected in an aortic dissection?

In an aortic dissection, the layer of the aorta that is primarily affected is the media. This middle layer of the aortic wall is composed of smooth muscle and elastic fibers, which provide structural support and elasticity. In the case of a dissection, a tear occurs in the intima, allowing blood to flow between the layers of the aortic wall, specifically separating the intima from the media and potentially causing a separation within the media itself.

While the intima is where the initial tear takes place, the critical dissection happens through the media, leading to the formation of a false lumen. The condition can subsequently compromise the aorta's integrity and blood flow, leading to significant complications. Understanding that the media is where the primary pathology occurs helps clarify why this layer is indeed the most directly impacted in an aortic dissection.