The dorsal column pathway carries sensations of highly localized touch, pressure, vibration, and proprioception. It involves the fasciculus gracilis and fasciculus cuneatus spinal tracts. First order sensory neurons carry information from cutaneous receptors and proprioceptors and synapse with second order neurons in the dorsal horn or medullary nuclei. These second order neurons transmit impulses to the thalamus. Third order neurons then project this information to the primary somatosensory cortex.

1. Dorsal column pathway DR SYED TOUSIF AHMED

2. General Sensory Receptors Sensory pathways Spinocerebellar Pathway Posterior Column Pathways Anteriolatheral Pathways Posterior Tract Anterior Tract Fasciculus Cuneatus Fasciculus Gracilis Latheral Tract Anterior Tract Sensory Pathways

3. Cutaneous sensory receptors Smooth skin (glaborous ) Hairy skin Free nerve endings The receptor location and its associated structure can alter the stimulus and influence the response Subcutis Dermis Epidermis Merkel disks detect steady pressure & are slowly adapting Free nerve endings around hair root can be either rapid or slowly adapting - depends on hair type Meissner’s corpuscles detect flutter & are rapidly adapting Pacinian corpuscles detect vibration & are very rapidly adapting Ruffini corpuscles detect steady pressure at higher threshold & are slowly adapting Free nerve endings in the skin are modality specific and can detect either pain or touch or pressure or temperature

8. Two-Point Discrimination

11. Somatosensory system receptor classification

18. Peripheral nerves system

19. Sensory Pathways and Ascending Tracts in the Spinal Cord

20. dorsal cloumn pathway

21. Dorsal column pathway

23. The Posterior Column Pathway and the Spinothalamic Tracts The area of sensory cortex devoted to a body region is relative to the number of sensory receptors.

24. Dorsal column pathway Large sensory nerves: Touch, vibration, two-point discrimination, proprioception Primary somatosensory cortex (S1) in parietal lobe Thalamus Medulla Medial lemniscus Spinal cord Dorsal column Dorsal column nuclei

27. Central Pathways

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