Final answer:
The medial lemniscal pathway, also known as the dorsal column system, is responsible for transmitting fine touch, vibration, and proprioceptive information to the brain. It consists of three neurons that relay signals from the periphery to the somatosensory cortex.
Step-by-step explanation:
The medial lemniscal pathway, also known as the dorsal column system, is one of the major sensory pathways in the body. It is responsible for transmitting fine touch, vibration, and proprioceptive information from the body to the brain. The pathway consists of three neurons that relay signals from the periphery to the somatosensory cortex.
The pathway starts with the axon of a primary sensory neuron entering the dorsal root and joining the dorsal column white matter in the spinal cord. As the axons enter the dorsal column, they arrange themselves based on their location in the body. Axons from the lower body position themselves medially, while axons from the upper body position themselves laterally. The dorsal column is divided into two tracts - the fasciculus gracilis, which carries information from the legs and lower body, and the fasciculus cuneatus, which carries information from the upper body and arms.
At the brain stem level, the axons in the dorsal column system decussate, or cross over to the opposite side of the brain. From there, the second neuron in the pathway carries the signal to the thalamus, where it synapses with the third neuron. The third neuron then projects the signal to the somatosensory cortex, where it is interpreted as touch or other sensory information.