The frontal bone (os frontale, TA: A02.1.03.001) is a bone in the human skull that resembles a cockle-shell in form, and consists of two portions—a vertical portion, the squama, corresponding with the region of the forehead; and an orbital or horizontal portion, which enters into the formation of the roofs of the orbital and nasal cavities. The Nomina Anatomica was one of the most popular systems for providing topographical codes in the 20th century. ... Grays illustration of a human femur, a typically recognized bone. ... [[|Diversity]] Binomial name Homo sapiens Linnaeus, 1758 Trinomial name Type Species Subspecies Homo sapiens idaltu (extinct) Homo sapiens sapiens [[Image: ]] Synonyms Homo (genus). ... A hippopotamus skull A skull, or cranium, is a bony structure of Craniates which serves as the general framework for a head. ... Genera Acanthocardia Americardia Cardium Cerastoderma Clinocardium Corculum Ctenocardia Dinocardium Discors Fragum Fulvia Laevicardium Lophocardiium Lyrocardium Lunulicardia Microcardium Nemocardium Papyridea Parvicardium Plagiocardium Ringicardium Trachycardium Trigoniocardia Serripes Cockles are the family Cardiidae of bivalve mollusks. ... The nasal cavity is a large air-filled space above and behind the nose in the middle of the face. ...

Squama (squama frontalis) or vertical part

Surfaces

Figure 1: Frontal bone, outer surface

The external surface [Fig. 1] of this portion is convex and usually exhibits, in the lower part of the middle line, the remains of the frontal or metopic suture; in infancy this suture divides the bone into two, a condition which may persist throughout life. Image File history File links Gray_134_-_Frontal_bone. ... Image File history File links Gray_134_-_Frontal_bone. ...

1. On either side of this suture, about 3 cm. above the supraorbital margin, is a rounded elevation, the frontal eminence (tuber frontale).
2. These eminences vary in size in different individuals, are occasionally unsymmetrical, and are especially prominent in young skulls; the surface of the bone above them is smooth, and covered by the galea aponeurotica.
3. Below the frontal eminences, and separated from them by a shallow groove, are two arched elevations, the superciliary arches; these are prominent medially, and are joined to one another by a smooth elevation named the glabella.
4. They are larger in the male than in the female, and their degree of prominence depends to some extent on the size of the frontal air sinuses; 28 prominent ridges are, however, occasionally associated with small air sinuses.
5. Beneath each superciliary arch is a curved and prominent margin, the supraorbital margin, which forms the upper boundary of the base of the orbit, and separates the squama from the orbital portion of the bone.
6. The lateral part of this margin is sharp and prominent, affording to the eye, in that situation, considerable protection from injury; the medial part is rounded.
7. At the junction of its medial and intermediate thirds is a notch, sometimes converted into a foramen, the supraorbital notch or foramen, which transmits the supraorbital vessels and nerve.
8. A small aperture in the upper part of the notch transmits a vein from the diploë to join the supraorbital vein.
9. The supraorbital margin ends laterally in the zygomatic process, which is strong and prominent, and articulates with the zygomatic bone.
10. Running upward and backward from this process is a well-marked line, the temporal line, which divides into the upper and lower temporal lines, continuous, in the articulated skull, with the corresponding lines on the parietal bone.
11. The area below and behind the temporal line forms the anterior part of the temporal fossa, and gives origin to the Temporalis muscle.
12. Between the supraorbital margins the squama projects downward to a level below that of the zygomatic processes; this portion is known as the nasal part and presents a rough, uneven interval, the nasal notch, which articulates on either side of the middle line with the nasal bone, and laterally with the frontal process of the maxilla and with the lacrimal.
13. The term nasion is applied to the middle of the frontonasal suture. From the center of the notch the nasal process projects downward and forward beneath the nasal bones and frontal processes of the maxillæ, and supports the bridge of the nose.
14. The nasal process ends below in a sharp spine, and on either side of this is a small grooved surface which enters into the formation of the roof of the corresponding nasal cavity.
15. The spine forms part of the septum of the nose, articulating in front with the crest of the nasal bones and behind with the perpendicular plate of the ethmoid.

The internal surface [Fig. 2] of the squama is concave and presents in the upper part of the middle line a vertical groove, the sagittal sulcus, the edges of which unite below to form a ridge, the frontal crest; the sulcus lodges the superior sagittal sinus, while its margins and the crest afford attachment to the falx cerebri. The Galea aponeurotica is connective tissue at the back of the head. ... The glabella is the space between the eyebrows and above the nose. ... In physics, an orbit is the path that an object makes, around another object, whilst under the influence of a source of centripetal force, such as gravity. ... In anatomy, a foramen is any opening. ... The zygomatic bone (also known as the zygoma; Os Zygomaticum; Malar Bone) is a paired bone of the human skull. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ... The temporalis muscle is one of the muscles of mastication. ... The maxillae are the largest bones of the face, except for the mandible, and form, by their union, the whole of the upper jaw. ... The nasion is the intersection of the frontal and two nasal bones of the human skull. ... The maxillae are the largest bones of the face, except for the mandible, and form, by their union, the whole of the upper jaw. ... A septum, in general, is a wall separating two cavities or two spaces containing a less dense material. ... The ethmoid bone (os ethmoidale) is a bone in the skull that separates the nasal cavity from the brain. ... A sulcus (pl. ... The falx cerebri (Latin: scythe of the brain) is an extension of the protective dura mater that projects into the longitudinal fissure that seperates the two cerebral hemispheres. ...

1. The crest ends below in a small notch which is converted into a foramen, the foramen cecum, by articulation with the ethmoid.
2. This foramen varies in size in different subjects, and is frequently impervious; when open, it transmits a vein from the nose to the superior sagittal sinus.
3. On either side of the middle line the bone presents depressions for the convolutions of the brain, and numerous small furrows for the anterior branches of the middle meningeal vessels.
4. Several small, irregular fossæ may also be seen on either side of the sagittal sulcus, for the reception of the arachnoid granulations.

The ethmoid bone (os ethmoidale) is a bone in the skull that separates the nasal cavity from the brain. ... Arachnoid granulations (and arachnoid villi) are small protrusions of the arachnoid (the thin second layer covering the brain) through the dura (the thick outer layer). ...

Orbital or horizontal part

This portion (pars orbitalis) consists of two thin triangular plates, the orbital plates, which form the vaults of the orbits, and are separated from one another by a median gap, the ethmoidal notch.

Figure 2: Frontal bone, inner surface

Image File history File links Gray_135_-_Frontal_bone. ... Image File history File links Gray_135_-_Frontal_bone. ...

Surfaces

• The inferior surface [Fig. 2] of each orbital plate is smooth and concave, and presents, laterally, under cover of the zygomatic process, a shallow depression, the lacrimal fossa, for the lacrimal gland; near the nasal part is a depression, the fovea trochlearis, or occasionally a small trochlear spine, for the attachment of the cartilaginous pulley of the Obliquus oculi superior.
• The superior surface is convex, and marked by depressions for the convolutions of the frontal lobes of the brain, and faint grooves for the meningeal branches of the ethmoidal vessels.
  • The ethmoidal notch separates the two orbital plates; it is quadrilateral, and filled, in the articulated skull, by the cribriform plate of the ethmoid.
    • The margins of the notch present several half-cells which, when united with corresponding half-cells on the upper surface of the ethmoid, complete the ethmoidal air cells.
  • Two grooves cross these edges transversely; they are converted into the anterior and posterior ethmoidal canals by the ethmoid, and open on the medial wall of the orbit.
    • The anterior canal transmits the nasociliary nerve and anterior ethmoidal vessels,
    • the posterior, the posterior ethmoidal nerve and vessels.

• In front of the ethmoidal notch, on either side of the frontal spine, are the openings of the frontal air sinuses.
  • These are two irregular cavities, which extend backward, upward, and lateralward for a variable distance between the two tables of the skull; they are separated from one another by a thin bony septum, which often deviates to one or other side, with the result that the sinuses are rarely symmetrical.
  • Absent at birth, they are usually fairly well-developed between the seventh and eighth years, but only reach their full size after puberty.
  • They vary in size in different persons, and are larger in men than in women.
  • They are lined by mucous membrane, and each communicates with the corresponding nasal cavity by means of a passage called the frontonasal duct.

The lacrimal bone (Os Lacrimale), the smallest and most fragile bone of the face, is situated at the front part of the medial wall of the orbit. ... Lacrimal apparatus of the right eye. ... The superior oblique muscle is a muscle in the orbit. ... The frontal lobe is an area in the brains of vertebrates. ... Comparative brain sizes In animals, the brain, or encephalon (Greek for in the head), acts as the control center of the central nervous system. ... The ethmoid bone (os ethmoidale) is a bone in the skull that separates the nasal cavity from the brain. ... The ethmoid bone (os ethmoidale) is a bone in the skull that separates the nasal cavity from the brain. ... In physics, an orbit is the path that an object makes, around another object, whilst under the influence of a source of centripetal force, such as gravity. ... The Ophthalmic nerve is one of the three branches of the trigeminal nerve, one of the cranial nerves. ... Grays Nerves of the orbit, and the ciliary ganglion. ... Puberty refers to the process of physical changes by which a childs body becomes an adult body capable of reproduction. ... The mucous membranes (or mucosae; singular: mucosa) are linings of ectodermic origin, covered in epithelium, and are involved in absorption and secretion. ... The nasal cavity is a large air-filled space above and behind the nose in the middle of the face. ...

Borders

The border of the squama is thick, strongly serrated, bevelled at the expense of the inner table above, where it rests upon the parietal bones, and at the expense of the outer table on either side, where it receives the lateral pressure of those bones; this border is continued below into a triangular, rough surface, which articulates with the great wing of the sphenoid. The posterior borders of the orbital plates are thin and serrated, and articulate with the small wings of the sphenoid. The sphenoid bone (os sphenoidale) is a bone situated at the base of the skull in front of the temporals and basilar part of the occipital. ...

Structure

The squama and the zygomatic processes are very thick, consisting of diploic tissue contained between two compact laminæ; the diploic tissue is absent in the regions occupied by the frontal air sinuses. The orbital portion is thin, translucent, and composed entirely of compact bone; hence the facility with which instruments can penetrate the cranium through this part of the orbit; when the frontal sinuses are exceptionally large they may extend backward for a considerable distance into the orbital portion, which in such cases also consists of only two tables. Lamina may refer to: Planar lamina, a 2 dimensional planar closed surface with mass and density (mathematics). ... Tables is a generic name given to a class of board games similar to Backgammon. ...

Ossification

Figure 3: Frontal bone at birth

The frontal bone is ossified [Fig. 3] in membrane from two primary centers, one for each half, which appear toward the end of the second month of fetal life, one above each supraorbital margin. Image File history File links Gray_136_-_Frontal_bone_at_birth. ... Image File history File links Gray_136_-_Frontal_bone_at_birth. ...

1. From each of these centers ossification extends upward to form the corresponding half of the squama, and backward to form the orbital plate.
2. The spine is ossified from a pair of secondary centers, on either side of the middle line; similar centers appear in the nasal part and zygomatic processes.
3. At birth the bone consists of two pieces, separated by the frontal suture, which is usually obliterated, except at its lower part, by the eighth year, but occasionally persists throughout life.
4. It is generally maintained that the development of the frontal sinuses begins at the end of the first or beginning of the second year, but Onodi’s researches indicate that development begins at birth.
5. The sinuses are of considerable size by the seventh or eighth year, but do not attain their full proportions until after puberty.

Articulations

The frontal articulates with twelve bones: the sphenoid, the ethmoid, the two parietals, the two nasals, the two maxillæ, the two lacrimals, and the two zygomatics. The sphenoid bone (os sphenoidale) is a bone situated at the base of the skull in front of the temporals and basilar part of the occipital. ... The ethmoid bone (os ethmoidale) is a bone in the skull that separates the nasal cavity from the brain. ... This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... The nasals are a pair of bones in the skull of many animals. ... The maxillae are the largest bones of the face, except for the mandible, and form, by their union, the whole of the upper jaw. ... The lacrimal bone (Os Lacrimale), the smallest and most fragile bone of the face, is situated at the front part of the medial wall of the orbit. ... Figure 1 : Left zygomatic bone The zygomatic bone (also known as the zygoma; Os Zygomaticum; Malar Bone) is a paired bone of the human skull. ...

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained herein may be outdated. Please edit the article if this is the case, and feel free to remove this notice when it is no longer relevant.
The public domain comprises the body of all creative works and other knowledge—writing, artwork, music, science, inventions, and others—in which no person or organization has any proprietary interest. ... Henry Grays Anatomy of the Human Body, commonly known as Grays Anatomy, is an anatomy textbook widely regarded as a classic work on human anatomy. ...

See also

• Bone terminology
• Terms for anatomical location