Final answer:
The dorsal column-medial lemniscus pathway is composed of three successive neurons. The first neuron originates from the dorsal root ganglion, the second neuron decussates in the medulla, and the third neuron carries the information to the primary somatosensory cortex.
Step-by-step explanation:
The dorsal column-medial lemniscus pathway is composed of three successive neurons.
The first neuron is an ascending sensory neuron that originates from the dorsal root ganglion and enters the dorsal column white matter in the spinal cord. These axons take a medial position for the lower body and a lateral position for the upper body.
The second neuron is an interneuron that decussates in the medulla and ascends to the thalamus through the medial lemniscus.
The third neuron is a thalamic neuron that carries the sensory information from the thalamus to the primary somatosensory cortex.