This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
[{'content': 'Ability to perceive shape and size is lost due to the lesion of \nSelect and explain. \nA. Tractus gracilis, B. Tractus cuneatus, C. Spinothalamic tract, D. Spinoreticular tract', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Though both tractus\xa0cuneatus\xa0& tractus gracilis are correct, since it is a single answer question, the best answer would be tractus cuneatus, as we commonly use hands to recognize size and shape of objects, more than the foot.\nSomatosensory cortex lesion- proprioception and tactile sensations are lost while pain and temperature sensations are preserved. \nTractus cuneatus- formed by fasciculus cuneatus (spinal cord) and nucleus cuneatus (medulla). Pass through the lateral portion of the dorsal column. \nCarries sensations of the dorsal column- proprioception and tactile sensations from the upper part of the body.\nTractus gracilis- formed by fasciculus gracilis (spinal cord) and nucleus gracilis (medulla). Pass through a medial portion of the dorsal column. \nCarries sensations of the dorsal column- proprioception and tactile sensations from the lower part of the body.', 'role': 'assistant'}]