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
Drug delivery to the brain would be required. For this to be effective there must be a mechanism for the removal of the active form of the drug from the brain tissue. These are drug compounds that increase the permeability of the blood–brain barrier. By decreasing the restrictiveness of the barrier, it is much easier to get a molecule to pass through it. These drugs increase the permeability of the blood–brain barrier temporarily by increasing the osmotic pressure in the blood which loosens the tight junctions between the endothelial cells. By loosening the tight junctions normal injection of drugs through an [IV] can take place