In a C5s-Fpz montage with lower extremity stimulation, the expected response is generated at which location?

In a C5s-Fpz montage with lower extremity stimulation, the expected response is generated at the caudal medial lemniscus. This anatomical structure is crucial in processing sensory information conveyed from the lower extremities. The medial lemniscus carries proprioceptive and fine touch sensory impulses, which originate in the lower body and ascend through the spinal cord. When stimulation occurs in the lower extremities, sensory input travels up the spinal cord, synapsing at various relay stations before reaching the brain.

The caudal medial lemniscus serves as a significant relay point as the sensory signals are transmitted towards the thalamus and subsequently to the primary somatosensory cortex. Given that the C5s electrode placement in the montage is designed to detect signals from the spinal cord and relay any sensory processing done by the medial lemniscus, the observed responses directly reflect activity at this structure during lower extremity stimulation.

Other locations like the cervical spine would correspond to initial sensory processing, and responses at the lumbar plexus may relate to peripheral nerve activity rather than central processing. In contrast, the motor cortex is responsible for executing movement rather than processing sensory input from lower extremity stimulation. Hence, the caudal medial lemniscus is the most appropriate