Arteries

Blood vessels that carry blood away from the heart.

Mnemonic of the heart as an archer carrying blood away from the heart as the arrows

Archery like an artery is away from the heart. Veins flow into the heart. Arteries flow away from the heart.

Dunce archers depicting arteries have thick walls

All archers have to do in a war is fire an arrow, when told. So you put your "thicker" people into your archery section.

Archery section = thicker.

So too

Arteries = thicker.

Note: arteries are thicker than veins.