Question

where does the upper motor neuron synapse with the lower motor neuron?
anterior horn of the spinal cord
posterior horn of the spinal cord
dorsal root ganglion
cerebral cortex

Explanation:

Upper motor neurons originate in the cerebral cortex/brainstem and travel to the spinal cord, where they form synapses with lower motor neurons in the anterior (ventral) horn. The posterior horn processes sensory input, the dorsal root ganglion contains sensory neuron cell bodies, and the cerebral cortex is the origin of upper motor neurons, not the synapse site.

Answer:

A. Anterior horn of the spinal cord