Chapter 50 Disorders of Motor Function. Motor Cortex. Highest level of motor function Precise, skillful, intentional movements Speech, flexor muscles of limbs, etc. Controlled by the primary, premotor and supplementary motor cortices in the frontal lobe
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Primary motor cortex
Responsible for execution of a movement.
Adjacent to central sulcus
(areas 6 and 8)
Generates intricate plan of movement.
Throwing a ball or picking up a fork
Supplementary motor cortex
The cerebellum receives continuous information about the sequence of muscle contractions from the brain
Extrapyramidal motor system
considerable weight or from a fall
blood in the cord – Hematomyelia
Parkinson disease (R) : atrophy of substantianigra
Parkinson disease: Lewy body
Michael J. Fox and Muhammad Ali
Read this story about Katharine and her family:
Multiple sclerosis plaques around ventricles
Alzheimer disease: progression
Alzheimer disease: plaques and tangles
Alzheimer disease: plaques (L) and tangles (R)
Symptoms usually appear before age 6 and may appear as early as infancy. They may include:
Fatigue, mental retardation, muscle weakness (begins in legs and pelvis), difficulty with motor skills (running, jumping hopping), frequent falls
May be confined to wheelchair by age of 12
b. Extrapyramidalmotor system: This system originates in the basal ganglia and provides background for the more crude, supportive movement patterns.
Demyelination is the causative factor in which disease?
Upper motoneuron (UMN’s)
1. Paralysis or weakness of movements of the affected side but gross movements may be produced.
2. Babinski sign is present:
3. Loss of performance of fine-skilled voluntary movements especially at the distal end of the limbs
4. Superficial abdominal reflexes and cremasteric reflex are absent.
5. Spasticity or hypertonicity of the muscles.
6. Clasp-knife reaction: initial higher resistance to movement is followed by a lesser resistance
7. Exaggerated deep tendon reflexes and clonus may be
Lower motoneurons (LMN’s)
1. Flaccid paralysis of muscles supplied.
2. Atrophy of muscles supplied.
3. Loss of reflexes of muscles supplied.
4. Muscles fasciculation (contraction of a group of fibers) due to irritation of the motor neurons – seen with naked eye