Water shed zone in spinal cord is

(B) T4-T8 > It is generally accepted that the gray matter in the watershed area of the midthoracic level of the spinal cord is the ischemic watershed zone of the spinal cord. Historically, the literature has supported the notion of a spinal cord "watershed zone" of ischemic vulnerability centered at the mid-thoracic level (T4 to T6 level). This assumption was based largely on anatomic studies and case reports describing the relative hypovascularity of the midthoracic region from approximately T4 to T8. Because of the anatomic distribution of the spinal cord arteries with the relative paucity of radicular arteries in the thoracic region, the midthoracic level (T4 to T8) has been recognized as the ischemic watershed zone of the spinal cord.