This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Brain , Subject name: Anatomy
A 64 year old male was undergoing aoic bypass surgery. During the procedure, the surgeon accidentally injured an aery arising from the aoa onn the left side at the level of lower thoracic that provides major blood supply to the spinal cord. Which of the following regions of the spinal cord is likely to be affected? 
Select and explain. 
A. Upper two thirds of the spinal cord, B. Lower two third of the spinal cord, C. upper one third of the spinal cord, D. Lower one third of the spinal cord
B: Lower two third of the spinal cord
Answer: B: Lower two third of the spinal cord 
Explanation: The aery of Adamkiewicz supplies the lower two-thirds of the spinal cord. The great anterior medullary aery of Adamkiewicz is a large feeder aery of the spinal cord. It originates from the aoa in the lower thoracic or upper lumbar veebral levels. It is unilateral and in majority of the people, enters the spinal cord from the left side. It may be the major source of blood for the lower 2/3rd of the cord. Damage to this aery can lead to paraplegia. It can be a feeder to the anterior spinal aery and ischemia of the anterior segment is associated with the aoic bypass procedure. Ref: Snell's Clinical Neuroanatomy 8th edition Pgno: 472