Arteriosclerosis is the term used to describe thickening and inelasticity of the walls of arteries.
There are two main patterns, of which atherosclerosis is the more common.
It is defined as the thickening and hardening of the walls of arteries as a consequence of the disease process called atheroma.

Arteriolosclerosis is thickening and hardening of the walls of small arteries and arterioles, usually caused by the presence of hypertension or diabetes.
This pattern of vascular damage is particularly seen in the kidneys and brain.

The consequence of narrowing of vessels is poor tissue perfusion with blood.
The consequence of inelasticity of vessels is a predisposition to vessel rupture and haemorrhage.
Alterations in the vascular endothelium also predispose to secondary thrombosis.

Atheroma and its consequences constitute the most common and important cause of disease and death in the Western world. Atheroma affects large- and medium-sized arteries, rarely involving arteries under 2 mm in diameter, and is confined to arteries exposed to the high pressures in the systemic circulation.

The arteries most severely affected by atheroma are the aorta, coronary, carotid, mesenteric, iliac and femoral arteries, and the cerebral arteries derived from both the vertebrobasilar and internal carotid arteries.

The intrarenal artery branches are thick walled and prominent, due to hypertensive arteriosclerosis.