Stereoanesthesia is due to lesion ofa) Nucleus Gracilisb) Nucleus cuneatusc) Cerebral cortexd) Spinothalamic tract
Astereognosis/Stereoanaesthesia- Loss of ability to recognize size and shape of an object.
Seen in- lesion of somatosensory cortex, lesion of tractus cuneatus, lesion of tractus gracilis.
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 lateral portion of dorsal column. Carries sensations of 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 medial portion of dorsal column. Carries sensations of dorsal column- proprioception and tactile sensations from lower part of the body.
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