Disorders of the Human Skull
. Possibly the commonest skull disease in humans is sinusitis. Sinuses are cavities in the frontal bones, the sphenoid bones, the maxillary bone, and the mastoid processes of the temporal bone that are lined with mucous membrane and that open into the nasal cavity. Sinuses are often infected by bacteria, causing inflammation and producing severe pain. Acute sinusitis is treated with antibiotics; chronic sinusitis is extremely difficult to eradicate. Skull deformity occasionally occurs in the womb or during delivery and is often accompanied by brain damage. The skull is also subject to fracture and to tumors. For skull measurement, see Cephalic Index .