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EXTRAPYRAMIDAL TRACTS
Motor fibers arising from cortical &
subcortical areas of brain descending
outside the corticospinal...
Extra Pyramidal System
1.Rubrospinal
2.Tectospinal
3.Lat. Vestibulospinal
4.Medial vestibulospinal
5.Pontine reticulospina...
Some peculiarities of individual
tract
• Rubrospinal –
- Red nucleus
- crossed
- located in lat. White column
- part of la...
•Tectospinal – crossed
- from sup. colliculus
- lower cervical region
- control reflex postural
movements in response to
v...
Reticulospinal tracts :
Support the body against gravity.
Two group of nuclei: Pontine & Medullary.
Function antagonistica...
Pontine
reticulospinal
tract
Medullary
reticulospinal
tract
Pontine reticular N.
Crossed and
uncrossed fibers
Ant. white c...
Medullary reticulospinal – Inhibitory input to
-- γ Motor neuron
-- bilateral
-- Extensors of proximal muscles of limb.
Ce...
• Normally, inhibitory control
of medullary reticulospinal
tract is prominent on the
muscle tone
Vestibulospinal tracts :
Works in association with Pontine reticular
nuclei (Pontine reticulospinal tract) to excite
antig...
Medial vestibulospinal Lat. vestibulospinal
Medial vestibular N.
Semicircular canals
Rotation of head
Ant. White column
Un...
cortex
Med. Ret. formation
Red n.
putamenC.N.
S.N.
Pontine. Ret. formationS.C.
Vesti. N.
cerebellum
+ α
+ α
- γ
+ γ
-γ
+ γ...
Functions of E.P.S.
1. Alternative channel for voluntary and
reflex activity.
2. Coarse movements of trunk & whole
limb.
3...
FUNCTIONS OF EPS
• Control of tone, posture and equilibrium.
• Control of complex movements (automatic
associated movement...
Pyramidal system Extrapyramidal system
Origin
Myelination
Course
Main control
controlled
muscle
Functions
Effects of
lesio...
Applied aspect :
1)Decerebrate rigidity.
2)Ischaemic decerebration.
Decerebrate rigidity : Transection at
midcollicular le...
Rigidity in antigravity muscles (neck, trunk &
extensors of legs.
Cause :Blockage of strong inhibitory input
from cortex, ...
Over excitation of pontine reticular
system(few fibres damaged).
Also the sensory influx while going to ARAS
gives collate...
2)Ischaemic decerebration : α rigidity
Both carotid & basilar arteries are tied so
excitation from Pontine reticular nucle...
Extrapyramidal system by Dr. Sunita M. Tiwale, Prof in Physiology,D. Y. Patil Medical College, Kolhapur
Extrapyramidal system by Dr. Sunita M. Tiwale, Prof in Physiology,D. Y. Patil Medical College, Kolhapur
Extrapyramidal system by Dr. Sunita M. Tiwale, Prof in Physiology,D. Y. Patil Medical College, Kolhapur
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Extrapyramidal system by Dr. Sunita M. Tiwale, Prof in Physiology,D. Y. Patil Medical College, Kolhapur

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Alternative mechanism/route for voluntary and reflex motor activity.
Form platform on which Pyramidal system work skillfully.

Veröffentlicht in: Gesundheit & Medizin
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Extrapyramidal system by Dr. Sunita M. Tiwale, Prof in Physiology,D. Y. Patil Medical College, Kolhapur

  1. 1. EXTRAPYRAMIDAL TRACTS Motor fibers arising from cortical & subcortical areas of brain descending outside the corticospinal tract, »-- reaching sp.cord. »-- Ending on α or γ motor neurons.motor neurons. »--ipsilat. or contralat. »--Multichannel system
  2. 2. Extra Pyramidal System 1.Rubrospinal 2.Tectospinal 3.Lat. Vestibulospinal 4.Medial vestibulospinal 5.Pontine reticulospinal 6.Medullary reticulospinal RRTV
  3. 3. Some peculiarities of individual tract • Rubrospinal – - Red nucleus - crossed - located in lat. White column - part of lat. motor system - extend up to mid tho. Level - facilitatory to flexors of wrist - do not control fine movements of hand & fingers.
  4. 4. •Tectospinal – crossed - from sup. colliculus - lower cervical region - control reflex postural movements in response to visual & auditory stimuli or visually guided move. of head
  5. 5. Reticulospinal tracts : Support the body against gravity. Two group of nuclei: Pontine & Medullary. Function antagonistically to each other. Pontine excites the antigravity muscles. Medullary inhibit the antigravity muscles.
  6. 6. Pontine reticulospinal tract Medullary reticulospinal tract Pontine reticular N. Crossed and uncrossed fibers Ant. white column Inhibit γ-motor neurons of extensors of body Maintain body posture Facilitate γ-motor neurons of extensors of body Medullary reticular.N.
  7. 7. Medullary reticulospinal – Inhibitory input to -- γ Motor neuron -- bilateral -- Extensors of proximal muscles of limb. Cerebral cortex via reticular formation sends inhibitory output from Medullary reti spinal tract to γ Motor neurons. Cerebellum also sends inhibitory drive via this tract. Function:Inhibits the antigravity in certain portions of the body to perform special motor activities.
  8. 8. • Normally, inhibitory control of medullary reticulospinal tract is prominent on the muscle tone
  9. 9. Vestibulospinal tracts : Works in association with Pontine reticular nuclei (Pontine reticulospinal tract) to excite antigravity muscles. Without the support of vestibular nuclei the pontine reticular system loses much of its excitation of axial antigravity muscles. Function :Controls selectively excitatory signals to different antigravity muscle to maintain equilibrium in response to signals from vestibular apparatus.
  10. 10. Medial vestibulospinal Lat. vestibulospinal Medial vestibular N. Semicircular canals Rotation of head Ant. White column Uncrossed fibers Through out the length of sp. cord Facilitation of extensors and inhibition of flexors Linear acceleration Utricle, saccule Lat. vesti. N. Uncrossed fibers Lat White column α-motor neurons
  11. 11. cortex Med. Ret. formation Red n. putamenC.N. S.N. Pontine. Ret. formationS.C. Vesti. N. cerebellum + α + α - γ + γ -γ + γ + α Midline
  12. 12. Functions of E.P.S. 1. Alternative channel for voluntary and reflex activity. 2. Coarse movements of trunk & whole limb. 3. Background posture. 4. Changing tone of muscle for smooth & purposeful movements.
  13. 13. FUNCTIONS OF EPS • Control of tone, posture and equilibrium. • Control of complex movements (automatic associated movements) of the body and limbs. • Cortex exerts tonic inhibitory control over lower centers through these tracts. So damage to these tracts→ Rigidity of muscle (release phenomena).
  14. 14. Pyramidal system Extrapyramidal system Origin Myelination Course Main control controlled muscle Functions Effects of lesion subcortical During iu life polysynaptic Lower extremity Postural muscles, Proximal jts Gross movements hypertonia Cortical After birth Monosynaptic Upper extremity Flexors of hand & fingers , distal jts Skilled movements hypotonia
  15. 15. Applied aspect : 1)Decerebrate rigidity. 2)Ischaemic decerebration. Decerebrate rigidity : Transection at midcollicular level of midbrain.
  16. 16. Rigidity in antigravity muscles (neck, trunk & extensors of legs. Cause :Blockage of strong inhibitory input from cortex, red nuclei & basal ganglia to medullary reticular nuclei. So medullary reticular sys less effective (nonfunctional) as depending solely upon cerebello bulbar connections for its inhibtory drive on spinal motor neurons.
  17. 17. Over excitation of pontine reticular system(few fibres damaged). Also the sensory influx while going to ARAS gives collaterals to Pontine reticular nuclei so facilitatory effect remains on γ motor activity which leads to rigidity. Hence called γ rigidity.
  18. 18. 2)Ischaemic decerebration : α rigidity Both carotid & basilar arteries are tied so excitation from Pontine reticular nuclei is blocked, still rigidity appears. Cause is over excitation of Vestibular nuclei through vestibulospinal tract which directly influences α motoneurons.

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