The nose communicates not only with the stomach and the lungs, but, as we shall see, with the ears, the eyes and the insides of the face-bone; it is also in close juxtaposition with the brain itself.
In the bones of the face there are hollow air-chambers, known as Sinuses, which give resonance to the voice and lightness to the otherwise solid masses of bone. The air chambers communicate with the nasal cavities on either side. The most important Sinuses are situated in the bones of the cheek and forehead and may become centres of pain and discomfort in a severe cold. When infection spreads to them, we may get sensations of dull, throbbing pain in the forehead, which gets worse in a heated atmosphere and on bending, or, if the lower sinuses are infected, the pain will seem to radiate from the cheek bone on either side. If such a condition does not clear up with the cold, a chronic state of sinusitis may set in, leading to persistent headaches and the discharge of matter into the nose, and occasioning much ill health. Gems multiplying in the sinuses may pour their poisons into the blood-stream and cause injury to such distant structures as the knee-joint or the great sciatic nerve of the leg. It has now become practically a routine measure in the treatment of rheumatism or neuritis and in many other diseases to investigate the condition of the sinuses.