Ascending & Descending nerve tracts

1. Ascending & Descending nerve tracts SanjayaAdikari Department of Anatomy

2. Control of the body by the brain L 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. Third order neuron Internal capsule Thalamus Corona radiata Medulla Second order neuron First order neuron Ascending tracts

9. Internal capsule Sensory Upper medulla Medulla Posterior surface

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

11. Internal capsule 20%

12. Internal capsule L Cranial nerves Corticobulbar Corticospinal Spinal nerves

13. Left Ascending tracts

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

15. Pain & temperature Lateral spinothalamic

16. Crude touch & pressure Anterior spinothalamic

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

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

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

20. Internal capsule Medulla

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

22. Superior, middle & inferior cerebellar peduncles

23. Left

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

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

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

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

31. A – Syringomyelia A

32. 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

33. B – Poliomyelitis B

34. C – Tabesdorsalis Demyelination C

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

36. Sensory ataxia of tabesdorsalis 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

37. 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

38. Refer Clinical Medicine by Kumar & Cleark’s