A 56 year old woman visited her family doctor for evaluation ofa headache that had persisted for nearly a month. Upon questioningthe patient, the doctor learned that her left arm, as she put it,\"was a bit unwieldy, hard to control and weak.\" Throughexamination, the doctor determined that the entire left upperextremity was generally weak. He also found weakness, although lesssignificant, of the left lower extremity. Sensation in the limbsseemed to be normal, although mild rigidity and hyperactivereflexes were present. Expressing concern, the doctor told thepatient that she needed a CT scan of her head and explained thatthere could be a problem within the brain, possibly a tumor orother lesion. The doctor then picked up the phone and contacted aradiologist. After explaining the patient's case, the doctorremarked parenthetically that he believed he knew where the problemwas located.

1) Why did the doctor suggest to the patient that there might bea problem within her brain when the symptoms were weakness of theextremities, and then just on one side of her body?

2) How would he know the location of the suspected braintumor?

3) In which side of the brain and in which lobe would it be?

4) Explain the muscle weakness in terms of neuronal pathwaysfrom the brain to the periphery.