The frontal sinus (Sinus frontalis) belongs like the maxillary sinus, sphenoidal sinus and the ethmoid cells to the paranasal sinuses (Sinus paranasales). It represents an air-filled cavity in the bone that forms the forehead and, like the other parts of the paranasal sinuses, it can also become inflamed, which is known as sinusitis (see below).
Anatomy
The frontal sinus consists of two separate cavities that are located in the frontal bone (Os frontale). The frontal sinus is thus located above the nasal cavity and also above the orbitae. Its rear wall already borders on the frontal base of the skull.
In the interior, the paired frontal sinus is covered by mucosa, which is covered on its surface with small, movable hairs (ciliated epithelium), comparable to the nasal mucosa. The function of these hairs is to transport foreign bodies and dust particles that have entered the sinus towards the nose. Towards the nasal cavity there is a small, crescent-shaped connection (Hiatus semilunaris), which opens into the middle nasal passage.
The bone in which the frontal sinus is located provides stability for the skull and thus protects the brain. The frontal sinus serves here for the lightweight construction of the bone, because without this air-filled cavity the bone would be very heavy and the head could not be lifted. Another function of the frontal sinus is to provide a resonance chamber for voice formation and thus to give the voice its individual sound and character.
Furthermore, the mucous membrane of the frontal sinus, which is well supplied with blood, should moisten and warm the air we breathe. The frontal sinus is not yet present from birth but is only formed in the course of life. It only reaches its final form when the growth of the skull is complete (usually between the ages of 20 and 25).
This explains why small children cannot yet develop sinusitis. Since the sinus only develops in the course of adolescence, it is not surprising that there is a high variability in the shape and appearance of the sinuses from one person to another. Often, the two caves are also differently big.
