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2. OBJECTIVES Anatomy of ascending and descending tracts of Spinal cord
Histology of spinal cord
To list the Function of various ascending and descending tracts
Terminology
Spinal cord injury
Management of spinal cord injury
4. Anatomy
5. Spinal Cord Organization Gray matter: mostly cell bodies
Dendrites & terminals
Spinal reflex integrating center
White matter
Bundles of myelinated axons
Ascending tracts sensory
Descending tracts motor
Dorsal roots
Ventral roots
6. Spinal Cord Organization
7.
18-7 Location of Tracts inside Cord Motor tracts Sensory tracts
pyramidal tract (corticospinal) ---spinothalamic tract
extrapyramidal tract ---posterior column
---spinocerebellar
8. Ascending Tracts major ascending
spinal cord tracts
posterior white column
spinothalamic
lateral and anterior
spinocerebellar
posterior and anterior
9. Ascending Tracts 1st order Neuron: Dorsal Root Ganglion (Spinal Ganglion)
2nd order Neuron: Spinal Cord
3rd order Neuron: Thalamus PLVNT
Termination: Cerebral Cortexpostcentral gyrus
12. Descending Tracts Major descending
spinal cord tracts
corticospinal
lateral and anterior
Reticulospinal
lateral, anterior and medial
Rubrospinal
15. Reticulospinal tract
16. Tectospinal tract
17. Rubrospinal tract
24. 1. posterior horn
2. anterior horn
3. intermediate zone (intermediate gray)
4. lateral horn
5. posterior funiculus
6. anterior funiculus
7. lateral funiculus
8. Lissauer's tract
9. anterior median fissure
10. posterior median sulcus
11. anterolateral sulcus
12. posterolateral sulcus
13. Posterior intermediate sulcus
26. Functions of Ascending Tracts : 1- Gracilis and Cuneatus tracts :
Discriminative touch
Vibratory sense
Conscious muscle joint sense (sense of position)
2- lateral spinothalamic tract :
Pain
Temperature
3- anterior spinothalamic tract :
- crude touch
-pressure
27. 4- spinotectal tract :
Provide afferent information for spinovisual reflexes and
brings movements of the eyes and head toward the source
of the stimulation .
5- spino-olivary tract :
Provides an indirect pathway for further afferent information to reach the cerebellum .
28. Functions of descending Tracts :
1- corticospinal tracts :
Rapid ,skilled,voluntary movements.especially distal ends of limbs
2- reticulospinal tracts :
Inhibit or faciliate voluntary movement .
3- tectospinal tracts :
Reflex postural movements concerning
Sight
29. 4- rubrospinal tract :
Faciliates activity of extensor muscles and inhibit flexor muscles
5- olivospinal tract :
May play a role in muscular activity,
But there is doubt that it exists
6- descending autonomic fibers :
are concerned with the control of visceral activity
- Control sympathetic and parasympathetic systems
30. Terminology Plegia = complete lesion
Paresis = some muscle strength is preserved
Tetraplegia (or quadriplegia)
Injury of the cervical spinal cord
Patient can usually still move his arms using the segments above the injury (e.g., in a C7 injury, the patient can still flex his forearms, using the C5 segment)
Paraplegia
Injury of the thoracic or lumbo-sacral cord, or cauda equina
Hemiplegia
Paralysis of one half of the body
Usually in brain injuries (e.g., stroke)
31. Nerve Tracts of the Spinal Cord
32. Spinal cord injuries
33. Sensory: how do you determine the level?
34. High cervical injuries (C3 and above) Motor and sensory deficits involve the entire arms and legs
35. Midcervical injuries (C3-C5) Varying degrees of diaphragm dysfunction
Usually need ventilatory assistance in the acute phase
Shock Due to interruption of the sympathetic input from hypothalamus to the cardiovascular centers
36. Low cervical injuries (C6-T1) Usually able to breathe, although occasionally cord swelling can lead to temporary C3-C5 involvement (need mechanical ventilation)
The level can be determined by physical exam
37. Thoracic injuries (T2-L1) Paraparesis or paraplegia
38. Cauda equina injuries (L2 or below) Paraparesis or paraplegia
39. What is the central cord syndrome? Usually occurs with a hyperextension of the cervical region
Cervical spinal cord involvement with arms more affected than legs
May occur with trauma, tumors, infections, etc
Traumatic lesions tend to improve in 1-2 weeks
Surgical decompression may be indicated if there is spinal stenosis
40. Brown-Sequard syndrome
42. Management Immobilization
Rigid collar
Sandbags and straps
Spine board
Log-roll to turn
Prevent hypotension
Pressors: Dopamine
Fluids to replace losses
Maintain oxygenation
O2 per nasal canula
If intubation is needed, do NOT move the neck
44. Gardner-Wells tongs
45. Soft and hard collars
46. Minerva vest and halo-vest
47. Long term care Rehab for maximizing motor function
Bladder/bowel training
Psychological and social support
48. Questions
49. Resources Neuroanatomy Snell
Medical physiology Gyuton
Physiology lectures dr.Faisal
Histology of SC lecture dr.M.Salah
50. Thank you