The smaller branches of arteries are called arterioles. 

Function: 

Arterioles distribute blood from the larger arteries to the capillaries, which are the smallest blood vessels. They regulate blood flow and pressure by constricting or dilating their walls. 

Structure: 

Arterioles have a thicker muscular layer than capillaries, but thinner than larger arteries. They are lined with endothelial cells, which form a smooth inner surface. 

Location: 

Arterioles are found throughout the body, branching off from arteries in all organs and tissues. 

Example: 

The radial artery in the forearm branches into arterioles that supply the muscles and skin of the hand.