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Frontal bone
Last reviewed: 23.04.2024
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The frontal bone (os frontale) participates in the formation of the anterior part of the roof (roof) of the skull, anterior cranial fossa and orbits. In the frontal bone, frontal scales, ocular and nasal parts are distinguished.
The frontal scales (squama frontalis) have a convex anterior surface, on which frontal tubercles are visible. From the inside, the frontal scales are concave, forming an internal surface facing the brain. Front frontal scales pass into the orbital parts, forming a pair of supraorbital margins (margo supraorbitalis). On the supraorbital margin, closer to the nose, there is an infraorbital incision (incisura supraorbitalis). Sometimes it closes, forming a supraorbital opening. In the medial part of the supraorbital margin, there is usually an insignificant frontal incision (incisura frontalis, s. Foramen frontale). The lateral supraorbital margin ends in a thick base and narrowed at the end with the zygomatic processus (processus zygomatics). From this process back and up goes the temporal line (linea temporalis). Above the supraorbital margin on either side is a cylindrical elevation - the superciliary arc (arcus superciliaris). Between the two superciliary arcs there is a flattened pad - glabella, or glabella.
The furrow of the upper sagittal sinus (sulcus sinus sagittalis superior) passes through the medial line on the inner (cerebral) surface of the scales. This furrow in front and below passes into the frontal crest, at the base of which there is a blind hole (foramen caecum) - the place of attachment of the process of the hard shell of the brain.
The partes orbitales are thin horizontal plates that participate in the formation of the upper wall of the orbitals. Between these plates is a deep incision (incisure ethmoidalis). In the region of the lateral corner of the ophthalmic part there is a depression - a pit of the lacrimal gland (fossa glandulae lacrimalis). In the medial part of the orbital part there is a fovea trochlearis (fovea trochlearis) and next to it - a bony protuberance - block awn. From the top on the orbital part of the so-called finger-like impressions and brain protrusions - the imprint of the frontal lobe of the brain.
The nasal part (pars nasalis) of the frontal bone is located between the orbital parts, bordering the front and sides of the trellis. On the sides of the pointed protrusion - nasal awn (spina nasalis) are visible holes - apertures of the frontal sinus leading to the frontal sinus. The frontal sinus (sinus frontalis) can have various configurations and sizes. The sinus communicates with the nasal cavity, it is lined with a mucous membrane and is filled with air.
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