1. Ascending & Descending nerve tracts
Sanjaya Adikari
Department of Anatomy

2. Control of the body by the brain
Contralateral representation
Decussation = Crossing R
Contralateral = Opposite side
Ipsilateral = Same side

3. L R
Medulla
Sensory
Sensory organs

4. L R
Medulla
Sensory
Sensory organs

5. L R
Medulla
Motor
Effecter organs

6. L R
Medulla
Motor
Effecter organs

7. L R
Medulla
Sensory organs
Effecter organs

8. Ascending tracts Third order neuron Internal capsule Thalamus
Medulla
Thalamus
Corona radiata
Second order neuron
Ascending tracts
First order neuron

9. Medulla
Internal capsule
Sensory
Posterior surface
Upper
medulla

10. Descending tracts Internal capsule Upper motor neuron
Anterior surface
Lower
medulla
Descending
tracts
Lower motor neuron
(Final common pathway)

11. Internal capsule
20%

12. L Corticobulbar Corticospinal Internal capsule Cranial nerves
Spinal nerves

13. Left
Ascending tracts

14. White columns Posterior white column Posterior nerve root
Lateral white column
Anterior white column
Anterior nerve root
Posterior nerve root

15. Lateral spinothalamic
Pain & temperature
Lateral spinothalamic

16. Crude touch & pressure
Anterior
spinothalamic

17. Internal capsule
Third order neuron
Medulla
Thalamus
Second order neuron
First order neuron

18. 8 8 9 9 10 10
Pain &
temperature
Crude touch &
pressure
Crosses within one spinal
segment
Crosses within several spinal
segments

19. Fine touch, vibration,
Conscious muscle & joint sense
Fasciculus gracilis
Fasciculus cuneatus

20. Medulla
Internal capsule

21. Muscle & joint sense to cerebellum
Anterior & posterior
spinocerebellar

22. Superior, middle & inferior
cerebellar peduncles

23. Left

24. Descending tracts Lateral corticospinal Olivospinal Rubrospinal
Vestibulospinal
Tectospinal
Rubrospinal
Anterior corticospinal

25. Left

26. Clinical Neuroanatomy by Richard S. Snell

27. Lemniscus
This term is used for some ascending (sensory) nerve tracts in the upper part of the medulla, pons and midbrain
Spinal lemniscus
combination of spinothalamic, spinotectal tracts
Medial lemniscus
crossed posterior column fibers
Lateral lemniscus
3rd neuron of auditory pathway

28. sensory motor R R 1 – All sensory and motor loss on contralateral side2
2 – Fine touch and vibration loss on the ipsilateral side, pain and temperature and motor weakness on the contralateral side 3
3 - Fine touch and vibration and motor weakness on the ipsilateral side, pain and temperature loss on the contralateral side (Brown-Sequard)

29. Unilateral cord lesion
Thalamic
Mid-braintem
Unilateral cord lesion
(Brown-Sequard)
Weakness
(UMN)
Clinical Medicine by Kumar & Cleark’s

30. 1 – All sensory and motor loss on contralateral side
2 – Fine touch and vibration loss on the ipsilateral side, pain and temperature and motor weakness on the contralateral side
3 - Fine touch and vibration and motor weakness on the ipsilateral side, pain and temperature loss on the contralateral side

31. Spinal cord lesions C D A B
Refer Clinical Medicine by Kumar & Cleark’s

32. A – Syringomyelia A

33. A – Syringomyelia
Loss of pain and temperature sense without loss of fine touch.
Discontinuous sensory loss
Loss of upper limb reflexes
Symptoms progress when the cavity enlarges
Clinical Medicine by Kumar & Cleark’s

34. B – Poliomyelitis B

35. C – Tabes dorsalis
Demyelination C

36. C – Tabes dorsalis (of neurosyphilis)
Demyelination of dorsal roots
Lightening pains, sensory ataxia, reflex and sensory loss, muscle wasting, charcot joints
Argyll Robertson pupils

37. Sensory ataxia of tabes dorsalis
This is due to loss of proprioception (position sense)
- stamping gait
- positive Romberg’s test
Argyll Robertson pupils
No reaction to light. Constricts to convergence
Lesion in the cerebral aqueduct

38. Anterior spinal artery occlusion
Bilateral loss of motor function due to damage to corticospinal tracts and anterior gray horns
Bilateral thermoanesthesia and analgesia due to damage to spinothalamic tracts
Loss of bladder and bowel control due to damage to descending autonomic tracts
Vibration, fine touch & position sense normal

39. Refer Clinical Medicine by Kumar & Cleark’s