The three yang meridians of both the hand and foot are directly connected with the head, the liver meridian also extends to the head, and the other yin meridians are indirectly connected with the head. The location of pain over the head can enable one to decide which meridian and which viscus are involved. For example, if neck is involved in headache, it is a problem related to the taiyang meridian; if pain appears on both sides of the head, it is a problem related to the shaoyang meridian and also connected with the gallbladder and triple energizer; if pain appears over the forehead and supraorbital bone, it is a problem related to the stomach and intestines; if pain appears over the vertex, it is a problem related to the jueyin meridian and connected with the liver. The causes of headache are various.

Headache of sthenia syndrome is usually caused by such factors like attack by exogenous wind, cold, summer-heat, dampness, pathogenic fire as well as obstruction or disturbance of the upper orifices by phlegm and blood stasis. Headache of asthenia syndrome is usually due to insufficiency of qi and blood and depletion of essence and marrow which fail to nourish the head. The causes and the types of headache should be analyzed according to the nature of headache and the accompanied symptoms.