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Some General Schemes 

Commands for voluntary movement originates in the cortical association areas (this is any area in the brain that is lying between and connecting on sensory projection area with another )

  1. The movements are planned in the cortex , basal ganglia and neocerebellum
  2. From the basal ganglia and neocerebellum (via the thalamus), there is projection to Premotor and motor cortex
  3. From the motor cortex (via the corticospinal tract and corticobulbar tract ) there is Projection to spinal motor neurons and homologous cranial nerve nuclei and there is movement
  4. There is feedback information of the movement (via the sensory input)
  5. The spinocerebellum in turn projects to the brain stem (via the rubro spinal , reticulospinal , tecto spinal and vestibulo spinal) for posture & coordination
  6. In the brains stem and the spinal cord,
  • The medial (or ventral , pathways / neurons subserve the muscles of the trunk and proximal portions of limbs )
  • The lateral pathways / neurons subserve the distal portions of the limbs
1.    The medial portions of anterior horns
2.    The ventral corticospinal tract and
3.    The medial descending pathways of brain stem (viz the tectospinal , retciulospinal and        vestibulo spinal tracts )
4.   Are concerned with adjustment of proximal muscles and posture
5.    Whereas
6.    The lateral corticospinal tract and
7.    The rubrospinal tarct are concerned with distal limb muscles (for skilled voluntary movements )
  1. The pyramidal tracts are the corticospinal tracts; strictly speaking it is only the lateral corticospinal tract, which should be called the pyramidal tract because it is only the lateral corticospinal tract that forms pyramids in the medulla. The extra pyramidal tracts are the rest of the descending pathways from the brainstem
  2. Cortical motor areas Motor cortex (the primary motor cortex) this is in the precentral gyrus (area 4) premotor cortex (area 6)
  3. Supplementary motor area (in the medial side of the hemisphere on and above the superior bank of the cingulated sulcus)
  4. Somatic sensory area I (in post – central gyrus )
  5. Somatic sensory area II (in the wall of the sylvian fissure ):
  1. Representation In the precentral gyrus
  2. There is a point for point representation in the precentral gyrus. The arrangement is such that the feet is represented at the top and the face at the bottom. Except the face area (which has bilateral representation), the rest of the representation is unilateral to the opposite side musculature)
  3. The size of the representation is proportional to the skill involved in voluntary movement e.g the speech and hand has a large area of representation.
  4. The premotor cortex may be concerned with setting posture at the start of planned movement
7. Supplementary motor area
  1. This is involved primarily in programming motor sequences
  2.  The posterior – parietal cortex (somatic sensory areas)
  3. This provides the origin of 40% of corticospinal and corticobulbar tracts. It also projects to premotor area . Its lesion results in inability to execute learned sequence of movements

(Lesions of the left motor cortex causes motor dysfunction of left and right hand whereas lesions of right motor cortex has little effect on right hand)
[Function of area 5: aiming of hands towards an object and manipulating it]

[Function of area 7: hand - eye coordination ]

  1. Corticospinal / corticobulbar tracts

1.  Origin:

a. 30% from motor cortex

b. 30% from premotor cortex

c. 40% from parietal lobe, especially somatic sensory ones

(The corticospinal fibres from parietal lobe is presumably concerned with direct sensory motor coordination)

Functions: - the corticospinal and corticobulbar tracts are the primary pathway for initiation of skilled voluntary movement


  • Lesion of lateral corticospinal tract:
  1. LOSS of control of distal muscles of limbs (which is concerned with fine, skilled movements)
  2. Hypotonia
  3. Extensor plantar response (Babinski’s sign)
  • Lesions of ventral corticospinal tract this causes axial muscle deficits (difficulty with balance, walking and climbing )
  • Lesion of extrapyramidal (posture – regulating pathways) causes spastic paralysis       


3.  Rubrospinal tract:

  1. Origin: Red nucleus (of the midbrain)
  2. Crossed pathway
  3. Afferents to red nucleus come from:
    1. Cerebral cortex
    2. Inhibits antigravity muscles (or extensors)
    3. For fine, skilled movement

4.  Tectospinal tract

Origin: superior colliculus of the midbrain

Crossed pathway

Afferents to superior colliculus:

  • Cerebral cortex (especially from occipital lobe
  • Superior colliculus

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