1. EXTRAPYRAMIDAL TRACTS & MOTOR NEURON LESIONS
Dr. SHAIKH MUJEEB AHMED
Assistant professor
AL MAAREFA COLLEGE

2. Learning Objectives At the end of this lecture you should be able to:
List the extrapyramidal tracts.
Summarize the functions of extrapyramidal tracts.
describe the signs and symptoms caused by a lesion of the spinal cord (fasciculus gracilis and fasciculus cuneatus, lateral corticospinal tract, and lateral spinothalamic tract).

3. Overview of Motor System
Corticospinal tracts
Corticobulbar tracts
Bulbospinal tracts

4. Overview of Motor System

5. CNS influence the activity of skeletal muscle through two sets of neuron
Upper motor neuron
Lower motor neuron

6. EXTRAPYRAMIDAL TRACTS-
corticospinal tract
EXTRAPYRAMIDAL TRACTS-
Reticulospinal Olivospinal
Vestibulospinal
Tectospinal
Rubrospinal tract
Corticobulbar tract
Corticorubral tract

7. Extrapyramidal tracts
Definition: Extrapyramidal tracts are those motor pathways which may act as the alternative route for volitional impulses and which form the platform on which pyramidal system works skillfully Integrated at various level from cerebral cortex to spinal cord
Cortical region controlling these tracts are area 8 and 6

8. Vestibulospinal Tract
Sp. cord
Medulla
Pons
Mid Brain
Cerebral Cortex
Corticospinal Tract
Tectospinal Tract
Rubrospinal Tract
Vestibulospinal Tract
Reticulospinal Tract SC RN VN
RFM
RFP

10. Position of tracts in the spinal cord

11. Function of Extrapyramidal tract
Cortinuclear fibre control movement of eyeball.
Other tract responsible for tone, posture(R.S. TRACT), visiospinal reflex(T.S TRACT), equilibrium(V.S. TRACT) Control complex movement( co-ordinated movement)
Exerts tonic inhibitory control over lower centers
Carry volitional impulse when pyramidal tract damage
The extrapyramidal system is responsible for sustained postures, resting tone and patterned movements.

12. ROLE OF EXTRAPYRAMIDAL SYSTEM
ATONIC
ExtraPyramidal system
Pyramidal system

13. Nerve pathways Descending Tracts Tract Signal function
Corticospinal (pyramidal)
Fine voluntary motor control of the limbs. The pathway also controls voluntary body posture adjustments.
Rubrospinal
Involved in involuntary adjustment of arm position in response to balance information; support of the body.
Reticulospinal (1) Pontine
Regulates various involuntary motor activities and assists in balance (leg extensors). Some pattern movements e.g. stepping
(2) Medullary
Inhibits firing of spinal and cranial motor neurons, control of antigravity muscles.
Vestibulospinal (1) Medial
It is responsible for adjusting posture to maintain balance (neck muscles).
(2) Lateral
It is responsible for adjusting posture to maintain balance (body/lower limb).
Tectospinal
Controls head and eye movements, Involved in involuntary adjustment of head position in response to visual information.

14. Descending Pathways Pathway Upper limb Lower limb Cortico/-pyramidal
This Tract functions to modulate the activity of Alpha or Gamma Motor Neurons as directed by the Motor Cortex.
Rubro-spinal
Stimulates flexors
Reticulo-spinal
Medullary inhibits extensors and excites flexors
Pontine excites extensors and inhibits flexors
(Generally upper limb)
Vestibulo-spinal
Doesn’t affect upper limbs but helps position head and neck in response to body tilting (medial)
Stimulates extensors (lateral)
Tecto-spinal
Control of head, neck and eye movements.

15. Extrapyramidal disorders
Lesions in the extrapyramidal tract cause various types of diskinesias or disorders of involuntary movement
Parkinsonism
Chorea
Hemiballism
Athetosis
Dystonia Tardive dyskinesia

16. Parkinsonism Degeneration of extrapyramidal tract Characterized by
Rigidity
Bradykinesia.
Tremors and
Postural deficits

17. Components of motor neurons
Upper motor neuron (corticospinal & corticobulbar).
Starts from motor cortex and ends in
Cranial nerve nucleus (corticobulbar).
Anterior horn of spinal cord in opposite side(corticospinal tracts).
Lower Motor Neuron
Starts from anterior horn of spinal cord and ends in appropriate muscle of the same side.
eg. All peripheral motor nerves.

18. UPPER AND LOWER MOTOR NEURON

20. DIFFERENCE BETWEEN UPPER & LOWER MOTOR NEURON LESION
UMN LESION
Paralysis affect movement rather than muscles
Muscle wasting is only from disuse, therefore slight. Occasionally marked in chronic severe lesions.
Spasticity of clasp-knife’ type. Muscles hypertonic.
LMN LESION
Individual muscle or group of muscles are affected.
Wasting pronounced.
Flaccidity. Muscles hypotonic.

21. Tendon reflexes increased. Clonus often present.
Superficial reflexes diminished or modified.
Abdominal reflex absent.
Babinski’s sign +ve, Increased jaw jerk.
Tendon reflexes diminished or absent.
Superficial reflexes often unaltered.

23. Lesion of the right dorsal column at L1 produces what impairment?
Click for answer
Damage to the right dorsal column at L1 causes the absence of light touch, vibration, and position sensation in the right leg. Only fasciculus gracilis exists below T6.
Click for explanation

24. Right Dorsal Column Lesion
Click to animate
DRG R L L1
Dorsal column lesion
Ipsilateral loss of light touch, vibration, and position sense
generalized below the lesion level
Below T6 only the fasciculus gracilis is present.
Common causes include MS, penetrating injuries, and compression from tumors.

25. R L
Lesion of the right lateral spinothalamic tract at L1 produces what impairment?
Click for answer
Damage to the right lateral spinothalamic tract at L1 causes the absence of pain and temperature sensation in the left leg.
Click for explanation

26. Right Lateral Spinothalamic Tract Lesion
Click to animate
DRG R L L1
Lateral spinothalamic tract lesion
Contralateral loss of pain and temperature sense
Common causes include MS, penetrating injuries, and compression from tumors.

27. R L
Lesion of the right lateral corticospinal tract at L1 produces what impairment?
Click for answer
Damage to the right lateral corticospinal tract at L1 causes upper motor neurons signs (weakness or paralysis, hyperreflexia, and hypertonia) in the right leg.
Click for explanation

28. Right Lateral Corticospinal Tract Lesion
UMN
Click to animate R L L1
Lateral corticospinal tract lesion
Ipsilateral upper motor neurons signs
generalized below the lesion level
UMN signs
Weakness (Spastic paralysis)
Hyperreflexia (+ Babinski, clonus)
Hypertonia
Common causes include penetrating injuries, lateral compression from tumors, and MS.

29. Complete transection of the right half the spinal cord (Hemicord or Brown-Sequard syndrome) at L1 produces what impairments? R L
Click for answer
Damage to the right dorsal columns at L1 causes the absence of light touch, vibration, and position sense in the right leg. Damage to the lateral corticospinal tract causes upper motor neuron signs in the right leg (Monoplegia), and damage to the lateral spinothalamic tract causes the absence of pain and temperature sensation in the left leg.
Click for explanation

30. Hemicord Lesion (Brown-Sequard Syndrome)
Click to animate R L L1
Hemicord lesion
Common causes include penetrating injuries, lateral compression from tumors, and MS.
Dorsal column lesion
Ipsilateral loss of light touch, vibration, and position sense
Lateral corticospinal tract lesion
Ipsilateral upper motor neurons signs
Lateral spinothalamic tract lesion
Contralateral loss of pain and temperature sense
Build the lesion

31. Hemicord Lesion (Brown-Sequard Syndrome)
UMN
Click to animate
DRG R L
DRG L1
Dorsal column lesion
Ipsilateral loss of light touch, vibration, and position sense
Lateral corticospinal tract lesion
Ipsilateral upper motor neurons signs
Lateral spinothalamic tract lesion
Contralateral loss of pain and temperature sense
Hemicord lesion