Cortical and brain stem control for motor system

?Located anterior to the central sulcus and occupying the posterior ? of frontal lobe.
?Subdivided into 3 sub areas
?Each has its own topographical representation of muscle groups and specific motor functions of the body.
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?Corresponds to Broadmann s area No. 4.
?Lies in precentral gyrus of the frontal lobe.
?Representation of body muscles in this area is characterized by:
1.Contralateral.
2.Inverted.
3.Size of represented area depends upon the movement performed by the muscles.
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A.Muscles perform fine movements represented by larger areas.
B.Muscles perform gross movements represented by smaller areas.
4.Definite somatotopic map for different parts of the body in which:
i.Feet represented at upper medial region.
ii.Face represented at lower lateral region.
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?N.B.
1)Several facial muscles are represented bilaterally.
2)Excitability of area 4 is high due to the presence of a large pyramidal cells called Betz cells
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1) Thalamus and somatic sensory area:
?Supplies motor area with information about sense of position and movements
?This provides sensory feed-back control of cortical motor activity.
2) Premotor and supplemental motor areas of the same side
3) Basal ganglia and cerebellum:
?To regulate and coordinate its motor activity.
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4) Visual and auditory areas:
?To provide information about spatial relations of the body to external environment.
5) Motor areas of the opposite side:
?To coordinate bilateral motor activities performed by both sides of the body.