Final answer:
The correct statement about the organization of somatic sensory system neurons is B, with the third-order neuron transmitting information from the thalamus to the cerebral cortex. Options A and C incorrectly describe the positions of first and second-order neurons. Neuron A, carrying sensory information, forms a synapse with neuron B in the CNS, while neuron A is part of the PNS, and the nerve containing neuron B's axon is part of the PNS and efferent.
The correct option is B. The neuron is in third order from the thalamus to the cerebral cortex
Step-by-step explanation:
The correct answer about the neuron organization of the somatic sensory system is B. The neuron is in third order from the thalamus to the cerebral cortex. Sensory information is transmitted through a series of three neurons: first, second, and third order. The first-order neuron travels from the sensory receptor to either the spinal cord or the brain stem, specifically the medulla, and does not travel between two parts of the medulla as option C suggests. The second-order neuron then carries the information to the thalamus. Finally, the third-order neuron carries the sensory information from the thalamus to the sensory cortex of the cerebral cortex where it is processed.
Addressing other parts of the somatic sensory system, part of neuron A (the axon of the first-order neuron) travels to the spinal cord. Neuron A then forms a chemical synapse with neuron B in the spinal cord, where neurotransmitters are released to transmit the signal from neuron A to neuron B. Neuron A is part of the peripheral nervous system (PNS) until it reaches the synapse within the CNS. The axon of neuron B traveling in a nerve to the skeletal muscle cell is part of the PNS, and this is considered an efferent nerve as it carries motor information away from the CNS to effectors such as muscles.
The correct option is B. The neuron is in third order from the thalamus to the cerebral cortex