Giant cell arteritis (GCA), also known as temporal arteritis, is a condition which causes inflammation on the inside of some blood vessels (arteries). It is called 'giant cell' because abnormal large cells develop in the wall of these inflamed arteries. The arteries affected are those which supply blood to the head. Several arteries may be affected at the same time; part of the aorta (the biggest artery in the body) is called the "arch of the aorta" - this is the part of the aorta which has arteries coming from it to supply the head with blood. These are the arteries that are typically affected by giant cell arteritis (temporal arteritis).
This is a companion discussion topic for the original article at https://patient.info/eye-care/visual-problems/temporal-arteritis-giant-cell-arteritis