Aneurysm in the brain. 3D angiography blood vessel X_ray footage that shows an aneurysm in blood vessels orange in the brain of a 45_year_old patient. The footage rotates the blood vessels to show them from different angles. The main blood vessel seen here is the left internal carotid artery, a major artery of the head and neck that supplies blood to the brain. This artery is being scanned to locate the cause of a subarachnoid haemorrhage, internal bleeding around the brain that can be caused by injuries or ruptures of aneurysms abnormal swellings in this and related arteries. An aneurysm is shown at the distal far end of the middle cerebral artery MCA, one of the arteries that branches off the internal carotid artery to supply the brain with blood. The blood vessels are visible on this X_ray footage because they have been injected with a radio_opaque contrast medium.