Head and neck anatomy may be important in the development of the BBB. Astrocytes may also be responsible for transporting ions (electrolytes) from the brain to the blood. Blood from the brain and neck flows from: (1) within the cranium via the internal jugular veins, a continuation of the sigmoid sinuses. The right and left external jugular veins drain from the parotid glands, facial muscles, scalp into the subclavian veins. The right and left vertebral veins drain the vertebrae and muscles into the right subclavian vein and into the superior vena cava, into the right atrium of the heart. The lymphatic system drains the
Varicose veins is returned by the deep veins, the superficial veins, which return only about 10% of the total blood of the legs, can usually be removed or ablated without serious harm. Secondary varicose veins are those developing as collateral pathways, typically after stenosis or occlusion of the deep veins, a common sequel of extensive deep venous thrombosis (DVT). Treatment options are usually support stockings, occasionally sclerotherapy and, rarely, limited surgery. Varicose veins are distinguished from reticular veins (blue veins) and spider veins, which also involve valvular insufficiency, by the size and location of the veins. Many patients who suffer with varicose