What is an arterial spasm?

Muscle contraction: Our arteries are lined on the inside with muscle. When this muscle contracts and stays like that it can narrow the diameter of the artery.

MedicineNet.com…: Provides this answer: coronary artery spasm: sudden constriction of an artery that deprives heart muscle of blood & oxygen can cause a type of sudden chest pain referred to as variant angina/prinzmetal angina. It can be triggered by emotional stress, medicines, street drugs (particularly cocaine), & exposure to extreme cold. Treatments include beta-blockers &, classically, Nitroglycerin to open aa.

Muscle contraction: The muscles in the arterial wall contract, causing the lumen, or space inside, to become smaller.

Arteries Constrict: Arteries, like veins, have layers of smooth muscle cells within their walls; many layers for arteries, fewer layers in veins. All the cells are oriented circumferentially. If the muscle cells contract, the inner opening for blood flow, gets smaller. Arterioles, the tiniest end arteries just prior to the capillaries, nerves to each, are most adept at changing size: control local flow & body wide bp.