1. Dermatomes overlap
Skin
Peripheral nerve
Dorsal
root
Ventral
root

2. Dermatomes overlap
Skin
Peripheral nerve
Dorsal
root
Ventral
root

3. Spinal cords Dorsal column Dorsal root ganglion Lateral column
“Anterolateral” column
Ventral column
Dorsal root
Spinal nerve
Dorsal horn
Intermediate zone
Ventral horn
Ventral root
Spinal cords

4. Receptor projections to systems
Bare nerve
ending
Anterolateral
system
Merkel’s receptor
Meissner’s
corpuscle
Pacinian
Dorsal column- medial lemniscal
system
Receptor projections to systems

5. Reminder: Rexed’s laminae
LgTermPatterns

6. DC lesion Somatotopic organization of the dorsal columns Rostral
Demyelination
Caudal
DC lesion

7. Lamina 5
Lg&SmTermPatterns

8. Lamina 5
Lg&SmTermPatterns

9. Anterolateral system X

10. Spinal Hemisection Ipsilateral loss of touch…
Contralateral loss of pain…
(2-3 segments caudal to injury)
Mechanoreceptor
Nociceptor

11. Syringomyelia • Bilateral loss of pain & thermal senses
Site of lesion
• Bilateral loss of pain & thermal senses
• Preservation of mechanosensations

12. Somatotopy of spinal paths

13. Dorsal column-medial lemniscal system
Anterolateral system
Dorsal column-medial lemniscal system
Postcentral gyrus / 1° SScx
Postcentral gyrus / Insular/ Cingulate cortex
Dorsal column nuclei
Dorsal horn
Also:
•Reticular formation
•Superior colliculus (mesencephalon)
Spinal commissure
Internal arcuate fibers
Pain, thermal, itch
Mechano…

14. Somatic Sensory Thalamus
Medial dorsal
Ventral posterior (VMpo)
Ventral posterior medial-VPM (trigem)
Ventral posterior lateral-VPL (spinal)
Touch
Pain

15. Leg area
Arm area
Face area
Internal capsule
Ventral posterior nucleus