The question is incomplete,below is the complete question.
Compare the dorsal column (medial lemniscal) and spinothalamic (anterolateral) pathways with respect to anatomy and sensory modality.
For the dorsal column (medial lemniscal) pathway,where are the cell bodies and axon terminals of the first -, second - and third - order
neurons?
Where does each pathway decussate?
Is the left side if the body represented in the right or left SI cortex?
Answer: THE DORSAL COLUMN - MEDIAL LEMNISCAL SYSTEM.
When cutaneous mechanoreceptors of the CNS collects external stimuli,axons from this mecahnosensory afferent neuron moves into the spinal cord via the dorsal roots and then further goes down ipsilaterally through those dorsal columns.then there will be topographic organization and nerve fibers with information from the lower limbs will then travel in the dorsal medial spinal cord. Then nerve fibers with information from the upper limbs will then travel in the dorsal lateral spinal cord.
Coming to the first synapse,the dorsal column nuclei of the of the lower medulla oblongata if the brain lowers the limb fibers synapse in the gracile nucleus that is located medially while the upper limb fibers synapse in the cuneate nucleus the is located laterally.
The internal arcuate fibers known as second order neurons then crosses to the contralateral side and travels up to the medial lemniscus.(decussation),this brings the lower limbs fibers to travel ventrally while the upper limb fibers travel dorsally.
The central posterior lateral nucleus of the thalamus VPL (ventral posterolateral nucleus) known as the second synapse, the third order neurons then travels to the primary somatosensory cortex(SI) or secondary somatosensory cortex (SII)