Migraine headaches are caused by a combination of enlarged blood vessels and chemicals that are released from nerve fibers around the blood vessels. Outside the skull around the temple areas of your head are arteries known as the temporal arteries. When a migraine happens, these arteries enlarge, and this stretches the nerves which are coiled around it. When those nerves are stretched, they release chemicals which cause inflammation, pain, and cause the arteries to enlarge more, which only increases the pain.
