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
Ability to perceive shape and size is lost due to the lesion of 
Select and explain. 
A. Tractus gracilis, B. Tractus cuneatus, C. Spinothalamic tract, D. Spinoreticular tract
B: Tractus cuneatus
Answer: B: Tractus cuneatus 
Explanation: Though both tractus cuneatus & 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.
Somatosensory cortex lesion- proprioception and tactile sensations are lost while pain and temperature sensations are preserved. 
Tractus cuneatus- formed by fasciculus cuneatus (spinal cord) and nucleus cuneatus (medulla). Pass through the lateral portion of the dorsal column. 
Carries sensations of the dorsal column- proprioception and tactile sensations from the upper part of the body.
Tractus gracilis- formed by fasciculus gracilis (spinal cord) and nucleus gracilis (medulla). Pass through a medial portion of the dorsal column. 
Carries sensations of the dorsal column- proprioception and tactile sensations from the lower part of the body.