What is third order neuron?

Answer 1

A second order neuron is the 2nd neuron to carry an order. The order could be a sensory stimulus or a motor stimulus. For e.g. in order to move a muscle, the order for that muscle to contract starts at the cerebral cortex in the somatomotor area. That is the first order neuron. The axon of the 1st order neuron will synapse with the 2nd order neuron at the level of the brain stem, which commonly decussate (crosses over) to the opposite side. In turn, the axon of the 2nd order neuron will descend along the spinal cord tracts where it will synapse with the 3rd order neuron. The 3rd order neuron is located in the ventral horn of the spinal cord, which will exit with the spinal nerve to supply the muscle.

Answer 2

First-order neurons conduct impulses from receptors of the skin and from proprioceptors (receptors located in a join, muscle or tendon) to the spinal cord or brain stem, where they synapse with second-order neurons. First-order neuron's cell bodes reside in gangion (dorsal root or cranial).

Answer 3

The afferent pathways consist of three sets of neurons: first, second, and third order. First order neurons carry signals from receptors to either the brain stem or spinal cord. Second order neurons carry signals from the spinal cord and brain stem to the thalamus, they cross-over (decussate) to the opposite side of these structures before reaching the thalamus.

Third order neurons connect the thalamus to thesomatosensory areas of the cortex where sensation is perceived.

Answer 4

Third order neurons have cell bodies in the thalamus and they relay impulses to the somatosensory cortex of the cerebrum (there are no third-order neurons in the cerebellum)