A carotid arteriogram is an x-ray study designed to determine if there is narrowing or other abnormality in the carotid artery, a main artery to the brain. This is an angiogram of the left common carotid artery (both front-to-back and side views) showing a severe narrowing (stenosis) of the internal carotid artery just beyond the division of the common carotid artery into the internal and external branches.

This is an angiogram of the right carotid artery showing a severe narrowing (stenosis) of the internal carotid artery just past the carotid fork. There is enlargement of the artery or ulceration in the area after the stenosis in this close-up film. Note the narrowed segment toward the bottom of the picture.

Rotational head movements cause the fluid in the cupula of the semicircular canal to "bend" the hair cells. The hair cells, in turn, send a signal to your brain that you are experiencing "motion".

Vertigo can occur when these hair cells are still sending signals of motion, even though you may be perfectly still, giving you the  "illusion of movement". 

Deep inside the head is the inner ear, which contains 3 small, fluid-filled structures called the semicircular canals (ducts). Each duct has a swelling at the end called the ampulla. Within the ampulla are tiny "balance" receptors called crista.