When they inject medication, usually Marcaine or Lidocaine, into the occipital nerve, right at the back of the head. This procedure, while painful, is a huge help for those who suffer from migraines.
Touch, pain, or temperature sensations in the scalp must be conveyed to the brain in order for us to “feel” them. Several nerves accomplish this purpose, and the greater occipital nerve is one of the more important ones. There are two greater occipital nerves, on each side of the head. Emerging from between bones of the spine in the upper neck, the two occipital nerves make their way through muscles at the back of the head and into the scalp, supplying feeling (including pain) to a good portion of the back and top of the head. They sometimes reach nearly as far forward as the forehead, but do not cover the face or the area near the ears; other nerves supply the feeling to these regions. Sometimes, even though they don’t reach the front of the head, through a mechanism called “referred pain,” irritation of one of the occipital nerves can be also be felt near the eye on the same side.
Like many other nerves, the greater occipital nerves can be “blocked”- or made numb with an injection of medication- to relieve pain.