A hiker in the woods unexpectedly steps on a nail that penetrates both their boot and bottom of their foot. Nociceptors in the hiker’s foot will relay the pain signal to the brain. In order to send pain signals to the brain, a nerve in the spinal cord would have to synapse with an:
A. afferent dorsal motor neuron
B. efferent ventral sensory neuron
C. afferent dorsal sensory neuron
D. efferent ventral motor neuron
Click for Explanation
Sensory neurons are afferent (from periphery to central) and enter dorsally within the spinal cord. Motor neurons are efferent (from central to periphery) and leave the spinal cord ventrally. An interneuron carrying pain sensation to the brain would synapse with an afferent, dorsal sensory neuron.
A. afferent dorsal motor neuron, incorrect, Motor neurons are efferent and ventral.
B. efferent ventral sensory neuron, incorrect, Sensory neurons are afferent and dorsal.
C. afferent dorsal sensory neuron, correct.
D. efferent ventral motor neuron, incorrect, Motor neurons are efferent and ventral, but an interneuron would synapse with the afferent sensory nerve in order to carry the incoming signal to the brain.
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