Frontal bone: anatomy and pathology

The frontal bone forms the cranial vault. It is connected with the sense organs (sight and smell), performing a double function, and consists of two sections: horizontal and vertical. The horizontal section is divided into an unpaired nasal and paired ophthalmic part.

The frontal bone consists of four parts: two ophthalmic, frontal scales and nasal. The frontal scales have the following surfaces: frontal (external), cerebral (internal) and two temporal (lateral). The frontal bone changed in the course of evolution, the frontal tubercles developed, so that the forehead changed enormously: from the slope it became convex. The frontal surface convex in front, smooth, along the middle line there is a slightly noticeable elevation. In the anterior regions, the outer surface of the scales passes into the orbital surface. The frontal bone (the surface of the scales) is separated from the temporal surface by an arcuate temporal line.

Diseases

Hyperostosis of the frontal bone or Morganyi-Morel-Stewart syndrome has been known to science for more than 250 years, but even today the scientists' interest in this pathology is not weakening. As a result of this disease, mental, vegetative-vascular and metabolic-hormonal disorders are observed. Some authors refer to obesity, hypertension, persistent headache as the main symptoms of hyperostosis. Often, this ailment is combined with mental disorders (atrophic myotonia, cerebral disorders, cerebral circulatory disorders, rheumatoid infection). However, no clear-cut etiologic factor has been established to date.

The osteoma of the frontal bone is a fairly rare disease, characterized by the formation of a benign tumor. It is suggested that the etiology of osteoma is associated with a hereditary factor (the probability of transmission of pathology to direct descendants is 50 percent), and congenital exostoses are also described.

Pathogenesis of the disease

There are three types of osteoma: solid, spongy and cerebral. Solid osteoma consists of a dense substance (lamina), which is located parallel to the surface of the tumor. The brain type of osteoma contains extensive cavities that are filled with bone marrow.

According to Virchow two more types of tumors are distinguished: heteroplastic (formed from connective tissue), hyperplastic (formed from bone tissue). The first group includes osteophytes - insignificant layers on the bone tissue. If they occupy the entire circumference of the bone, then they are called hyperostosis. If the bone mass is given in the form of a tumor in a limited place, then it is an exostosis, if it is inside the bone - an enostosis.

Clinical signs of osteoma

Osteomas developing on the inner surface of the frontal bone are accompanied by frequent headaches, epileptic seizures, memory disorders, symptoms of increased intracranial pressure. If the tumor is localized in the area of the "Turkish saddle," hormonal imbalance may manifest. When localized in the zone of the paranasal sinuses, diplopia, exophthalmos, ptosis, anisocoria, decreased vision, etc. develop.

Most often, osteomas are localized on the outer (lateral) surface of the bone. Osteomas localized on the outer plate of the bones of the skull manifest themselves as a dense, painless and immovable formation. The diagnosis is based on clinical and radiological data. With extracranial growth of the tumor, breathing, smell, and sometimes deformed facial skeleton.

Yet most often the osteoma spreads intracranially. Such neoplasms destroy the posterior wall of the frontal sinuses, cause compression of the medulla. If an infection joins this pathological process, arachnoiditis develops, brain abscess, meningitis. Differentiate the disease from osteogenic sarcoma and osteomyelitis. Neoplasms are removed surgically.