Dr Haji Khan Kkhoharo\ Muhammad Medical College Mirpurkhas

1. Ascending Pathways Dr Haji Khan Khoharo

2. For conscious perception: Dorsal column Medial Lemniscal system Spinothalamic system For unconscious perception: Spino-cerebellar Spino-olivary Spino-tectal Spino-reticular Ascending Pathways

3. Three-neuron pathways: Primary sensory neurons: From external receptors Travel through dorsal roots of spinal cord Secondary neurons: Make up tracts in spinal cord and brainstem/ Medulla Tertiary neurons: From thalamus to primary sensory cortex Travel through internal capsule Ascending Pathways

4. Spinal Cord Tracts

5. Modality : Touch, pressure, vibration, Two-point discrimination, Stereognosis proprioception Receptor : Most receptors except free nerve endings 1st Neuron : Dorsal Root Ganglion (Spinal Ganglion) Posterior Root - Posterior White Column 2nd Neuron : Dorsal Column Nuclei (Nucleus Gracilis et Cuneatus) Internal Arcuate Fiber - Lemniscal Decussation - Medial Lemniscus 3rd Neuron: Thalamus (VPLc) Internal Capsule ----- Corona Radiata Termination : Area 3,1,2 Dorsal column medial lemniscal pathway

9. Dorsal Column Medial lemniscal Pathway Sensory Modalities : Touch, pressure, vibration, two-point discrimination, proprioception Areas 3,1,2 Thalamus: 3 rd order Medulla Medial lemniscus Spinal cord DRG-1 st order N.Gracilis N.Cuneatus (2 nd order )

11. Stereognosis: “ability to recognize the form of objects by touch.” Barognosis: “ability to recognize weight.” Graphesthesia: “recognition of numbers, letters, or symbols traced on the skin.” Dorsal column medial lemniscal pathway

12. Sub-Acute Combined Degeneration Lesion - posterior white column - corticospinal tract (UMN) Symptom - sensory ataxia Astereognosis loss of discriminative touch, proprioception below the level of lesion - ipsilateral UMN syndrome below the level of lesion

13. Sub-Acute Combined Degeneration Sub-Acute Combined Degeneration 1. corticospinal tract 2. posterior white column

14. THANK YOU 4 Attention