Tracts (ascending and descending)


Published on

Published in: Health & Medicine, Technology
  • My name is Jessica Luis, and I base in USA...My life is back!!! After 1 years of Broken marriage, my husband left me with two kids . I felt like my life was about to end i almost committed suicide, i was emotionally down for a very long time. Thanks to a spell caster called Dr Mohammed, which i met online. On one faithful day, as I was browsing through the internet,I came across allot of testimonies about this particular spell caster. Some people testified that he brought their Ex lover back, some testified that he restores womb,cure cancer,and other sickness, some testified that he can cast a spell to stop divorce and so on. i also come across one particular testimony,it was about a woman called Sonia,she testified about how he brought back her Ex lover in less than 2 days, and at the end of her testimony she dropped Dr Mohammed's e-mail address. After reading all these,I decided to give it a try. I contacted him via email and explained my problem to him. In just 48hours, my husband came back to me. We solved our issues, and we are even happier than before Dr Mohammed, is really a gifted man and i will not stop publishing him because he is a wonderful man... If you have a problem and you are looking for a real and genuine spell caster to solve all your problems for you. Try High anytime, he might be the answer to your problems. Here's his contact: or call him +2348134493948
    Are you sure you want to  Yes  No
    Your message goes here
    Are you sure you want to  Yes  No
    Your message goes here
  • very very nice
    Are you sure you want to  Yes  No
    Your message goes here
    Are you sure you want to  Yes  No
    Your message goes here
  • very nice ...balance with neuroanatomy snell. jazak ALLAH
    Are you sure you want to  Yes  No
    Your message goes here
No Downloads
Total views
On SlideShare
From Embeds
Number of Embeds
Embeds 0
No embeds

No notes for slide

Tracts (ascending and descending)

  1. 1. Ascending and Descending Tracts SMS 1084 Dr. Mohanad R. Alwan
  2. 2. <ul><li>Contents </li></ul><ul><ul><li>function of nervous system in general </li></ul></ul><ul><ul><li>sensory system overview </li></ul></ul><ul><ul><li>spinal cord and nerve tracts </li></ul></ul><ul><ul><ul><li>ascending tracts </li></ul></ul></ul><ul><ul><ul><ul><li>organization in general </li></ul></ul></ul></ul><ul><ul><ul><ul><li>ascending tracts </li></ul></ul></ul></ul><ul><ul><ul><ul><li>functional components </li></ul></ul></ul></ul>
  3. 3. <ul><li>Nervous System </li></ul><ul><li>Communication </li></ul><ul><li>receive information </li></ul><ul><li>transform it into impulses ( transduction ) </li></ul><ul><li>transmit impulses to the CNS </li></ul><ul><li>correlate / coordinate </li></ul><ul><li>transmit impulses to the effector organs </li></ul><ul><li>response / action </li></ul>
  4. 4. CENTRAL NERVOUS SYSTEM integration / processing / modulating stimulus receptor neurone motor / descending tracts effector organ / response PNS transmission lower motor neurone sensory / ascending tracts
  5. 5. <ul><li>Ascending Tracts </li></ul><ul><li>bundles of nerve fibres </li></ul><ul><li>linking </li></ul><ul><ul><ul><li>spinal cord with higher centres of the brain </li></ul></ul></ul><ul><li>convey information </li></ul><ul><li>from </li></ul><ul><li>soma / viscera to higher level of neuraxis (CNS) </li></ul>
  6. 6. Ascending Sensory Pathway are organized in three neuronal chain - First order neurone - Second order neurone - Third order neurone
  7. 7. <ul><li>First order neurone </li></ul><ul><li>cell body in posterior root ganglion </li></ul><ul><li>peripheral process connects with sensory receptor ending </li></ul><ul><li>central process enter the spinal cord through the posterior root </li></ul><ul><li>synapse with second order neuron in spinal gray matter </li></ul>
  8. 8. dorsal root dorsal root ganglion spinal nerve dorsal horn FIRST ORDER NEURON
  9. 9. <ul><li>Second order neurone </li></ul><ul><li>cell body in posterior gray column of spinal cord </li></ul><ul><li>axon crosses the midline ( decussate ) </li></ul><ul><li>ascend & synapse with third order neuron in VPL nucleus of thalamus </li></ul>
  10. 10. SECOND ORDER NEURON <ul><li>cross the mid line </li></ul><ul><li>in front of central canal </li></ul>VPL 1 st 2 nd
  11. 11. <ul><li>Third order neurone </li></ul><ul><li>cell body in the thalamus </li></ul><ul><li>give rise to projection fibres to the cerebral cortex, postcentral gyrus ( sensory area ) </li></ul>
  12. 12. ascending sensory pathway ( in general form ) from sensory endings to cerebral cortex ( note the three neurons chain )
  13. 13. ascending tracts in spinal cord
  14. 14. <ul><li>lateral spinothalamic tract </li></ul><ul><ul><li>pain, temperature </li></ul></ul><ul><li>anterior spinothalamic tract </li></ul><ul><ul><li>touch, pressure </li></ul></ul>Tracts & Their Functional Components
  15. 15. <ul><li>posterior white column </li></ul><ul><ul><li>conscious proprioceptive sense, discriminative touch, vibratory sense </li></ul></ul><ul><li>spinocerebellar tract / cuneocerebellar tract </li></ul><ul><ul><li>unconscious information from muscle, joints, skin, subcutaneous tissues </li></ul></ul>
  16. 16. <ul><li>Lateral spinothalamic tract </li></ul><ul><li>pain and thermal impulses </li></ul><ul><li>( input from free nerve endings, thermal receptors ) </li></ul><ul><li>transmitted to spinal cord in delta A and C fibres </li></ul><ul><li>central process enters the spinal cord through posterior nerve root , proceed to the tip of the dorsal gray column </li></ul>
  17. 17. pain and temperature pathways
  18. 18. <ul><li>Anterior spinothalamic tract </li></ul><ul><li>light touch and pressure impulses </li></ul><ul><li>( input from free nerve endings, Merkel’s tactile disks ) </li></ul><ul><li>First order neuron </li></ul><ul><ul><li>dorsal root ganglion( all level ) </li></ul></ul><ul><li>Second order neuron </li></ul><ul><ul><li>in the dorsal horn, cross to the opposite side (decussate) </li></ul></ul><ul><ul><li>ascend in the contralateral ventral column </li></ul></ul><ul><ul><li>end in VPL nucleus of thalamus </li></ul></ul><ul><li>Third order neuron </li></ul><ul><ul><li>in the VPL nucleus of thalamus </li></ul></ul><ul><ul><li>project to cerebral cortex ( area 3, 1 and 2 ) </li></ul></ul>
  19. 19. Touch and pressure pathways
  20. 20. <ul><li>Posterior & anterior spinocerebellar tract </li></ul><ul><li>Transmit unconscious proprioceptive information to the cerebellum </li></ul><ul><li>receive input from muscle spindles, and pressure receptors </li></ul><ul><li>involved in coordination of posture and movement of individual muscles of the lower limb </li></ul>
  21. 21. muscle joint sense pathways to cerebellum
  22. 22. <ul><li>Spinotectal tract </li></ul><ul><ul><li>passes pain, thermal, tactile information to superior colliculus for spinovisual reflexes </li></ul></ul><ul><ul><ul><li>cross the median plane </li></ul></ul></ul><ul><ul><ul><li>synapse in the superior colliculus </li></ul></ul></ul><ul><ul><ul><li>integrate visual and somatic sensory information ( it brings about the movement of eye and head towards the source of information ) </li></ul></ul></ul><ul><li>Spinoreticular tract </li></ul><ul><ul><li>uncrossed fibres, synapse with neurones of reticular formation (important role in influencing level of consciousness ) </li></ul></ul><ul><li>Spino-olivary tract </li></ul>
  23. 23. Spinotectal tract Spinoreticular tract Spino-oloivary tract
  24. 24. <ul><li>Descending Tracts </li></ul><ul><li>Segregated bundles of nerve fibres in the white matter of the spinal cord descending from the supraspinal centres </li></ul><ul><ul><li>referred to as upper motor neurons ( UMN ) </li></ul></ul><ul><li>are concerned with somatic and visceral motor activity </li></ul><ul><li>cells of origin lie in cerebral cortex and brain stem </li></ul><ul><li>regulate the LMN activity </li></ul>
  25. 25. motor homunculus cerebral cortex
  26. 26. <ul><li>lower motor neurons ( LMN ) </li></ul><ul><li>motor neurons that innervate the voluntary muscles </li></ul><ul><li>in anterior gray column of spinal cord / </li></ul><ul><li>motor nuclei of brainstem </li></ul><ul><ul><li>innervate skeletal muscles </li></ul></ul><ul><li>form final common pathway </li></ul>LMN
  27. 27. <ul><li>LMN </li></ul><ul><li>constantly bombarded by </li></ul><ul><li>nerve impulses( excitatory or inhibitory ) </li></ul><ul><ul><li>that descend from cerebral cortex, </li></ul></ul><ul><ul><li>pons, </li></ul></ul><ul><ul><li>midbrain and </li></ul></ul><ul><ul><li>medulla </li></ul></ul><ul><li>sensory inputs from the posterior root </li></ul>
  28. 28. <ul><li>Upper motor neurons ( UMN ) </li></ul><ul><li>The descending supraspinal pathways that influence the activity of the LMN </li></ul>
  29. 29. <ul><li>UMN </li></ul><ul><li>control voluntary motor activity </li></ul><ul><li>maintenance of posture & equilibrium </li></ul><ul><li>control of muscle tone and reflex activity </li></ul><ul><li>generally exerts their effect </li></ul><ul><li>on groups of muscles ( not on one specific muscle ) </li></ul><ul><li>reciprocally on agonist and antagonist muscle group </li></ul>
  30. 30. cerebral cortex – midbrain - pons - medulla oblongata descending tracts LMN sensory inputs
  31. 32. <ul><li>Corticospinal tract </li></ul><ul><li>arises from the pyramidal cells of cerebral cortex </li></ul><ul><ul><li>fibres travel through </li></ul></ul><ul><ul><ul><li>corona radiata </li></ul></ul></ul><ul><ul><ul><li>posterior limb of the internal capsule </li></ul></ul></ul><ul><ul><ul><li>cerebral peduncle ( middle 3/ 5 th ) </li></ul></ul></ul><ul><ul><ul><li>pons </li></ul></ul></ul><ul><ul><ul><li>medulla oblongata ( passed through the pyramids ) </li></ul></ul></ul><ul><ul><li>eventually fibres cross the mid line and terminate on LMN of anterior gray column of respective spinal cord segments </li></ul></ul>
  32. 33. motor decussation medulla oblongata
  33. 34. Corticospinal Tract for fine skilled movements
  34. 35. <ul><li>Rubrospinal tract </li></ul><ul><li>nerve cells in red nucleus </li></ul><ul><li>( tegmentum of midbrain at the level of superior colliculus ) </li></ul><ul><li>nerve fibres / axons </li></ul><ul><ul><li>cross the mid line </li></ul></ul><ul><ul><li>descend as rubrospinal tract </li></ul></ul><ul><ul><ul><li>through pons and medulla oblongata </li></ul></ul></ul><ul><li>terminate anterior gray column of spinal cord </li></ul><ul><li>( facilitate the activity of flexor muscles ) </li></ul>
  35. 37. <ul><li>Tectospinal tract </li></ul><ul><li>nerve cells in superior colliculus of the midbrain </li></ul><ul><li>nerve fibres/ axons </li></ul><ul><ul><li>cross the mid line </li></ul></ul><ul><ul><li>descend close to medial longitudinal fasciculus </li></ul></ul><ul><li>terminate in the anterior gray column of upper cervical segments of spinal cord </li></ul><ul><li>( responsible for reflex movement of </li></ul><ul><li>head & neck in response to visual stimuli ) </li></ul>
  36. 39. <ul><li>Vestibulospinal tract </li></ul><ul><li>nerve cells in vestibular nucleus (in the pons and medulla oblongata </li></ul><ul><ul><li>received afferents from inner ear and cerebellum </li></ul></ul><ul><li>axons descend uncrossed </li></ul><ul><ul><li>through medulla and through the length of spinal cord </li></ul></ul><ul><li>synapse with neuron in the anterior gray column of the spinal cord </li></ul><ul><li>( balance by facilitate the activity of the extensor muscles ) </li></ul>
  37. 41. <ul><li>Reticulospinal tract </li></ul><ul><li>nerve cells in reticular formation </li></ul><ul><li>fibres pass through </li></ul><ul><ul><li>midbrain, pons, and medulla oblongata </li></ul></ul><ul><li>end at the anterior gray column of spinal cord </li></ul><ul><ul><li>control activity of motor neurons </li></ul></ul><ul><li>(influence voluntary movement and reflex activity ) </li></ul>
  38. 42. Reticulospinal Tract
  39. 43. Thank You