There are 31 pairs of nerves originating from the spinal cord called spinal nerves; there are 8 cervical, 12 thoracic, 5 lumbar, 5 sacral and 1 coccygeal.
Since the trigeminal and sacral nuclei serve just one side of the face or body, herpes vesicles and ulcers develop on the ipsilateral or same side as the affected nuclei.
These are grouped into 8 pairs of cervical nerves, 12 pairs of thoracic nerves, 5 pairs of lumbar nerves, 5 pairs of sacral nerves and 1 pair of coccygeal nerves.
The resulting nerve impulses zip along afferent fibers to the sacral region of the spinal cord, along interneurons, and toward the brain, eventually exciting the parasympathetic neurons and inhibiting the sympathetic system.
And with the exception of a couple of sacral nerves near the tailbone that run to the bladder and genitals and rectum, most of these nerves never go through the spinal cord.
The skull is connected to the cervical vertebrate in the neck, then the dorsal vertebrate in the back, then the sacral vertebrate are fused to the hips, followed by the cotal vertebrate of the tail.