Nov 27, 2017 "Exact?" "Plaque?" "Builds up" "Harden"

"The exact cause of atherosclerosis isn't known" is a quote from the NIH public information web site of the National Heart, Lung and Blood Institute. The word "exact" , here, seems to me deliberately misleading. If they knew even approximately what causes it, then they would tell you what they know for sure, what are the main gaps in our knowledge, what are some competing alternative explanations? In contrast, the Wikipedia article on the same subject says: " The cause is not known" But they cite the NIH article as their own source!

What is "Plaque"? Does it mean anything to say that plaque builds up? There gets to be more of it?
It's an irregular tangle of live smooth muscle cells, semi-deceased macrophages, full of vacuoles containing fatty acids and cholesterol, collagen fibers, extracellular crystals of fats and calcium salts.

Why doesn't plaque build up in veins? Why not mini-plaques in capillaries? Why not in ducts?
Why don't such materials accumulate in muscles? Are there theories why not?
Why doesn't the outside surface of arteries bulge outward as a result of plaque; why is all the bulging inward? Has any research tested alternative explanations?
Doesn't that imply stronger rigidity of outer parts, as compared with plaque?
The "Athero" part of the word atherosclerosis comes from the Greek word for porridge.
which seems contrary to arteries becoming "hardened" in the sense of more rigid and fragile.

Can new arteries be induced to form by rearrangement of smooth muscle cells, fibroblasts, collagen fibers and endothelial cells? All 4 cell types crawl actively when put in tissue culture. Platelets too.
Is cell locomotion of artery wall cells part of what causes atherosclerosis?
Are there any consistent abnormalities in the locomotion of cells from "plaque"?

Let's discuss the following quote: "Plaque may begin to build up where the arteries are damaged. Over time, plaque hardens and narrows the arteries. Eventually, an area of plaque can rupture (break open). When this happens, blood cell fragments called platelets (PLATE-lets) stick to the site of the injury. They may clump together to form blood clots. Clots narrow the arteries even more."
I underlined words and phrases of special interest for discussion.
"Typically, atherosclerosis begins in childhood, as a thin layer of white-yellowish streaks with (???) the inner layers of the artery walls (an accumulation of white blood cells, mostly monocytes/macrophages) and progresses from there." Quote from the very good Wikipedia article on atherosclerosis. Maybe "with" is a typo?