Function of motor cortex
Controls contraction of specific groups of muscles
Regulated complex discrete precise and skilled movements
Participates in cognitive planning or motor activity
Executes movements based upon constant feedback from cortical and subcortical areas
Brain stem
Cranial nerves
Speech movements
Skilled movements
Lesion above pyramidal decussation
Signs contralateral to the site of lesion
Lesion below the pyramidal decussarion
Spinal UMN and LMN
Signs ipsilateral to site of lesion
Monoplegia
One limb
Hemiplegia
One half of body
Triplegia
Three limbs
Quadriplegia
All four limbs
UMN syndrome
Cortical motor neurons and their efferenta
Delayed muscle spacicity
Increased tone and reflexes and paralysis
Cortical neurons and axons before the synapse on spinal or cranial nuclei
Also cdmlee pyramidal neurons because descending axons pass through pyramids of medulla
LMN
brain stem and spinal cord
Flaccid paralysis, decreased tone and reflexes and muscle atrophy
Muscle spasiticy
Increased muscle tone with resistance to psssive manipulation
Descending pathways
Corticospinal
Corticonuclear (corticobulbar)
Corticospinal Tract
Control of voluntary movements of
Skeletal muscles through activation of spinal motor neurons
30% of fibers
Corticobulbar Tract
Control of head and facial muscles through activation of cranial nerve nuclei
Remaining 70% short fibers
Lesion to middle cerebral artery
Lateral surface
Of Cortex affects upper limb and face
Lesion to anterior cerebral artery
Sagittarius surface of cortex affects leg and toes
Spastic hemiplegia
Lesions to corticospinal tract (UMN)
Contralateral hemiplegia
Hyoertonia, hyperflexia, altered reflexes
Abdominal and positive babinski
Corticobulbar syndrome
Lesions to UMN unilateral
Paralysis of facial,
Lingual,
Palatial, and laryngeal muscles
Rarely observers in facial muscles
Spacicity, rigidity, hypertonicity
Cva,
Rumors, degenerative disorders
Pseudobulbar palsy
Speech musculature paralysis from bilateral corticobulbar involvement
Lack of motor control of facial muscles for delicate and discrete movements
Exaggerated emotional responses- excessive
Laughter, sobbing
Effects of corticobulbar system lesion
Unilateral
Variable degrees of contralateral paresis in oral structures jaw and tongue deviation away from lesion site
Greater motor difficulty with unilaterally innervsted structures alike the lower face and tongue than upper eyes and forehead
Bilateral
Paeudobulbar palsy
Profound effect on facial expression speech swallowing and phonation
Alternating hemiplegia
Ipsilateral and contralateral
Vagus- flaccid paralysis of pharyngeal and laryngeal muscles
Facial- facial asymmetry and effect on eating and phonation
Hypoglossal- flaccid paralysis of intrinsic and extrinsic lingual muscles, eating, and phonation and speaking disturbances
Contralateral hemiplegia- involvement of motor fibers
Before crossing
Interruption of LMN AND UMN= alternating patterns of symptoms