Neuralgia is the sensation of pain along a nerve or nerve pathway. Cranial neuralgia is this type of pain associated with the nerves of the head.

Twelve pairs of cranial nerves connect the base of the brain to the sense organs and muscles of the head. The nerves pass through small openings (foramina) in the skull, with one of each pair going to the right and the other going to the left side of the head.

The cranial nerves are part of the peripheral nervous system. They do not process information like the brain and spinal cord (central nervous system). Instead, they carry signals from the senses (sensory neurons) and transmit commands to the muscles and glands (motor neurons).

Cranial nerves are identified by name and Roman numeral. For example, the largest nerve in the skull (trigeminal nerve) is also known as the fifth cranial nerve. They may be sensory neurons, motor neurons or a mix. The 12 pairs of cranial nerves are:

• I. Olfactory. Sensory neuron related to smell.
  
  
• II. Optic. Sensory neuron related to vision.
  
  
• III. Oculomotor. Motor neuron involved in movement of the eyelids and eyes.
  
  
• IV. Trochlear. Motor neuron involved in eye movement.
  
  
• V. Trigeminal. Mixed function. Sensory function is related to facial skin and its motor function controls chewing.
  
  
• VI. Abducent. Motor neuron involved in eye movement.
  
  
• VII. Facial. Mixed function. Sensory neuron related to taste as well as motor function for facial expression and mouth movement.
  
  
• VIII. Vestibulocochlear (also known as the auditory or acoustic nerves). Sensory neuron related to hearing and balance.
  
  
• IX. Glossopharyngeal. Mixed function. Senses taste and controls glands in mouth and swallowing muscles.
  
  
• X. Vagus. Mixed function. Sensory function is related to skin of and near the ears and motor control of glands in the membranes of chest and abdomen organs (e.g., heart, lungs, intestines).
  
  
• XI. Accessory. Motor neuron involved in swallowing and head and shoulder movement.
  
  
• XII. Hypoglossal. Motor neuron involved in tongue movement.

Most cases of cranial neuralgia are related to damage to the trigeminal nerve, but any of the cranial nerves may be affected, such as the glossopharyngeal or vagus nerves. This damage may be linked to compression, infection or inflammation of the nerves, but in many cases there are no apparent physical changes causing the pain.

Neuralgia may also affect the occipital nerve, which provides sensory information from the back of the head but is not a cranial nerve. Instead it exits the spinal cord, near where the spine meets the skull. Cranial neuralgia can involve any of these nerves and the resulting pain is often felt in the face, scalp, neck, throat or inside the mouth.