Question

Which of the following is FALSE regarding the synapses of upper motor neurons?

A. Upper motor neurons originating in the cerebral cortex terminate contralaterally in the medial ventral horn
B. Upper motor neurons originating in the brainstem travel ipsilaterally through the anterior-medial white matter of the spinal cord until they reach synapse level
C. Upper motor neurons originating in the brainstem synapse with lower motor neurons for posture and balance control
D. Upper motor neurons originating in the cerebral cortex cross the midline prior to traveling through lateral white matter of the spinal cord to their synapse location
E. None, all of the above are TRUE

Answer 1

The false statement is that upper motor neurons originating in the cerebral cortex terminate contralaterally in the medial ventral horn. Upper motor neurons actually synapse at various points in the ventral horn, not necessarily terminating in the medial ventral horn contralaterally.

Step-by-step explanation:

The statement that is FALSE regarding the synapses of upper motor neurons is: 'Upper motor neurons originating in the cerebral cortex terminate contralaterally in the medial ventral horn'. This statement is false because the upper motor neurons that originate in the cerebral cortex, specifically the Betz cells from the primary motor cortex, will decussate and then travel through the lateral white matter to reach various levels of the spinal cord where they will synapse. They do not necessarily terminate contralaterally in the medial ventral horn; instead, they may synapse at various points with lower motor neurons which are found throughout the ventral horn.

Lower motor neurons control various aspects of muscle function including posture, balance control, and precise movements. While the anterior corticospinal tract (which controls the muscles of the body trunk) remains ipsilateral and then decussate at the spinal level to enter the ventral horn, the corticospinal tract primarily crosses over at the level of the brainstem (decussation of the pyramids) before descending through the spinal cord.