INFLAMMATION, PERIOSTITIS, OSTITIS, CARIES, and NECROSIS may occur in the cranial bones. The symptoms are very similar to those produced by the same processes elsewhere. In necrosis of the cranial bones there is always the dan terior branch of the middle meningeal artery and the bifurcation of the Syl vian fissure; AC follows its horizontal limb. The lateral sinus at its highest point touches the line PS at R. MA corresponds to the precentral sulcus, and, if it be trisected at K and L, these points will correspond to the origins of the superior and inferior frontal sulci. The supramarginal convolution lies in the triangle II BC. The angular gyrus o'er of extension of the inflammation to the membranes of the brain and inflam matory effusion within the skull, pro ducing convulsions, coma, or death. Af fection of the petrous portion of the temporal bone gives rise to the greatest danger, on account of the homogeneous structure of the bone and the continuity of the dura miter with the lining of the cavities by which it is perforated. When the frontal bone or the vault is the seat of disease, cerebral complications are less likely to occur.
Symptoms.—When the vault or fore head is affected there is tenderness, with some puffiness, and gradual elevation of the scalp into an abscess. If this be opened, the necrosed bone may be seen or felt at the bottom of a sinus or un healed ulcer. When the petrol's portion
of the temporal bone is affected, there will be a history of earache, followed by a profuse fcetid discharge from the ear, with tympanic 'perforation, escape of the middle-ear bones, and deafness. When the sphenoid or ethmoid is affected, deep-seated pains in the head. persistent mdema of the eyelids, and a fcetid dis charge from the nose will be present.
Etiology. — These inflammatory dis orders of the cranial bones are usually consequent upon injury or constitutional syphilis; more rarely they result from strnma (tuberculosis) or follow typhoid fever.
Prognosis.—Neerosis of the petrol's portion of the temporal bone is generally incurable, death usually resulting from encephalitis. In necrosis of the sphe noid or ethmoid little can be expected from operative interference, though in the latter case portions of the seques trum may occasionally be extracted through the nasal cavity.
Treatment.—The treatment of the in flammatory disorders of the bones of the skull follows the general rule of treat ment of these disorders. It is, however, especially important that by absolute cleanliness, frequent dressings, and the liberal use of antiseptics, the parts be kept, as far as possible, in an aseptic condition. (See also OssEorrs SYSTEM, DISEASES OF.)