Answer :
Final answer:
The Spinocerebellar pathway does not use tertiary neurons, contrary to the Dorsal Column-Medial Lemniscal and Spinothalamic pathways, which both utilize a series of three neurons to relay sensory information to the somatosensory cortex. The correct option is c.
Explanation:
The somatosensory pathway that does not use tertiary neurons is c. the Spinocerebellar pathway. Unlike the Dorsal Column-Medial Lemniscal pathway and the Spinothalamic pathway, which both consist of a triad of neurons concluding their transmission in the somatosensory cortex, the Spinocerebellar pathway primarily carries proprioceptive information directly to the cerebellum without a third-order neuron.
Both the Dorsal Column-Medial Lemniscal and Spinothalamic pathways utilize first-order sensory neurons that have their cell bodies in the dorsal root ganglion, second-order neurons that transmit the signals to the thalamus, and third-order thalamic neurons that project to the primary somatosensory cortex. In contrast, the Spinocerebellar pathway has its sensory inputs integrated within the cerebellum, which is crucial for coordination and precision of movements, negating the need for the relay through a third-order neuron to the cerebral cortex.
