Varicella zoster virus is one of the herpesviruses and it causes two diseases - varicella or chickenpox, and herpes zoster also known as shingles.
Zoster actually refers to a type of belt used by ancient Greek warriors because of the belt like appearance of shingles.
Now, let’s first talk a bit about the nervous system - it consists of two parts.
The central nervous system which includes the brain and the spinal cord, and the peripheral nervous system includes the nerves that fan out from the central nervous system to reach the skin, muscles, and organs.
Peripheral nerves that originate from the brain are called cranial nerves, and they’re in charge of motor and sensory innervation of the head and neck.
A specific cranial nerve, cranial nerve V, is the trigeminal nerve and it’s responsible for the sensation in the face.
Its sensory neurons create a nerve cell cluster called trigeminal ganglion, located in the bones on the side of the face between the eyes and ears.
The peripheral nerves originating from the spinal cord are called the spinal nerves.
Each nerve is formed by a dorsal and a ventral root.
Ventral roots contains neurons that carry motor innervation from the spinal cord to the muscles.
Sensory information, like touch, temperature, pain, and pressure from the skin and other tissues travel through 1st order sensory neurons, in the dorsal root ganglion near the spinal cord, then through the dorsal root, and into the spinal cord, where it synapses with the 2nd order neurons.