The Brain and the Spinal Cord

There are three types of Dura, the epidural space, dura mater, and subdural space. The epidural space is the space external to the sac of the spinal dura mater within the vertebral canal. The dura mater is the outermost of the meningeal layers covering the brain and spinal cord. The dura has a hard leathery outside. The subdural space is a fluid-filled space or potential space between the dura mater and the arachnoid. The arachnoid has no blood supplies and is web-like. The sub-arachnoid space is the cerebra spinal fluid.The pia mater is the delicate membrane that lies on surface of the brain and spinal cord.
Vessels are confluence like, two or more vessels will met and flow together with the same amount of blood. The vessels full of blood flow from the lungs where they become oxygenated to the left atrium to the bicuspid-mistral value. After the bicuspid-mistral value then to left ventricle to the semi lunar value then ascends to the aora then to the aortic arch. From the aortic arch the blood descends to the aorta.The blood also flows through the aortic arch to the right brachiocephalic to the right subclavian, and finally right common caryatid.