Headache is a common clinical symptom, and the main mechanisms that produce headache include: 1) dilation of intracranial and extracranial arteries, mostly seen in intracranial infections, metabolic diseases, and toxic diseases; 2) pulling or displacement of intracranial nociceptive-sensitive tissues, most often seen in intracranial tumors, intracranial hematomas, hydrocephalus, and low cranial pressure, etc.; 3) inflammation of extracranial and extracranial sensory-sensitive tissues; 4) extracranial muscular constriction; 5) direct damage or inflammation of the cerebral nerves and cervical nerves that transmit nociceptive sensations, such as trigeminal neuralgia and cervical neuralgia, etc.; 6) lesions of the eyes, ears, nose, and teeth, and the diffusion of pain, etc.; and 7) disruption of high-level neurologic activity, as seen in neurologic disorders and severe psychosis.