Final answer:
Cerebral palsy is the motor function disorder caused by a permanent, nonprogressive brain defect or lesion during the perinatal period.
Step-by-step explanation:
The motor function disorder that is a result of a permanent, nonprogressive brain defect or lesion caused perinatally is cerebral palsy. Unlike other neurodegenerative diseases such as Parkinson's disease, Huntington's disease, or multiple sclerosis, cerebral palsy results from injury to the developing brain either during pregnancy, childbirth, or immediately after birth.
It is not progressive, meaning the brain damage does not worsen over time, though the symptoms can change in severity. Parkinson's disease, on the other hand, is characterized by the progressive death of neurons in the midbrain, predominantly affecting dopamine production leading to its classic motor symptoms like tremor, rigidity, and bradykinesia.