The inability to perceive the texture & shape an object occurs in a lesion of: (A) Lateral spino-thalamic tract, (B) Nucleus gracilis, (C) Spino reticular tract, (D) Nucleus cuneatus
Answer is D. Though both nucleus cuneatus & nucleus 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 upper part of the body.
Tractus gracilis- formed by fasciculus gracilis (spinal cord) and nucleus gracilis (medulla). Pass through the medial portion of the dorsal column. Carries sensations of the dorsal column- proprioception and tactile sensations from the lower part of the body.