Sample NBDE Part I Question  Directions: Read the following
question and select the best answer from the choices below.
Which of the following components of the extrapyramidal system
primarily function to control skeletal muscle tone?    1.
Cerebellar nuclei   2. Cerebral nuclei   3. Red nucleus   4.
Superior colliculi   5. Vestibular nuclei  Answer & Explanation:
The answer is C.  The axons of the pyramidal cells of the motor
cortex descend to synapse on lower motor neurons in the brain
stem and the spinal cord. Since there are no intervening
synapses, the pyramidal system is able to provide rapid commands
to the skeletal muscles and various other organs. There are
several other centers that can issue somatic motor commands as a
result of processing performed at the unconscious, involuntary
level. These centers and their associated tracts comprise the
extrapyramidal system. The red nucleus, located in the
mesencephalon, is the component of the extrapyramidal system
primarily in control of skeletal muscle t