ANATOMY

Detailed explanation-1: -Unlike arteries, veins contain valves that ensure blood flows in only one direction. (Arteries don’t require valves because pressure from the heart is so strong that blood is only able to flow in one direction.)

Detailed explanation-2: -Background: The ophthalmic and facial veins are frequently stated to be devoid of valves, facilitating the spread of infection from the mid-face to the cavernous sinus.

Detailed explanation-3: -Vein vs Artery. Veins are closer to the surface of your body, and arteries are deep inside your muscles. The walls of a vein are thinner than an artery. Veins carry blood from your organs and towards your heart. Arteries carry blood away from your heart.

Detailed explanation-4: -Why are valves present in veins but not in arteries? In veins, blood flows against gravity and at a low pressure back to the heart, so veins have valves to prevent back flow. Arteries have high pressure which propels the blood through them.

Detailed explanation-5: -Many veins, particularly those in the arms and legs, have one-way valves. Each valve consists of two flaps (cusps or leaflets) with edges that meet. Blood flowing toward the heart pushes the flaps open like a pair of one-way swinging doors.