Headache

In medicine, a headache or cephalalgia is a symptom of a number of different conditions of the head. Headache is caused by a disturbance of the pain-sensitive structures in the head. The brain in itself is not sensitive to pain, because it lacks nociceptors. Several areas of the head and neck have the pain-sensitive structures. The pain-sensitive structures are divided in two: within the cranium (blood vessels, meninges, and the cranial nerves) and outside the cranium (the periosteum of the skull, muscles, nerves, arteries and veins, subcutaneous tissues, eyes, ears, sinuses and mucous membranes).