References. 1  Hess CL, Howard MA, Attinger CE. 2  McCulloch J. Physical modalities in wound management: ultrasound, Vasopneumatic devices and hydrotherapy. 3  Davis SC, Ovington LG.  Dyson M. Therapeutic application of ultrasound.
The three major sensory tracts involve chains of neurons â¢ First-order neuron â¢ Delivers sensations to the CNS â¢ The cell body is in the dorsal or cranial root ganglion â¢ Second-order neuron â¢ An interneuron with the cell body in the spinal cord or brain â¢ Third-order neuron â¢ Transmits information from the thalamus to the cerebral cortex. 1  Comments.
By function[change | change source] Sensory neurons carry signals from sense organs to the spinal cord and brain. Relay neurons carry messages from one part of the CNS. Motor neurons carry signals from the CNS to muscles, motor neurons are connected to the relay neurons. The signal passes between the neurons via synapses.