C
Figure 3. A myelomere of the spinal cord, and one of its two associated spinal nerves. In A: A, anterior median fissure; P, posterior median sulcus. B shows the arterial supply to the cord. C depicts a sensory axon in the dorsal nerve root and a somatic motor axon in the ventral nerve root. Additionally, there is a sympathetic preganglionic axon arising from a neuron in the spinal cord lateral horn and this is traversing the white ramus communicans to the sympathetic gangliated chain where it is synapsing on a small postganglionic neuron. A and B by permission of R. O'Rahilly, "Basic Human Anatomy."