Squama frontalis
Encyclopedia
There are two surfaces of the squama
of the frontal bone
: the external surface, and the internal surface.
On either side of this suture, about 3 cm. above the supraorbital margin, is a rounded elevation, the frontal eminence
(tuber frontale).
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
.
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
. 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; prominent ridges are, however, occasionally associated with small air sinuses.
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.
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.
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.
A small aperture in the upper part of the notch transmits a vein from the diploë
to join the supraorbital vein
.
The supraorbital margin ends laterally in the zygomatic process
, which is strong and prominent, and articulates with the zygomatic bone
.
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.
The area below and behind the temporal line forms the anterior part of the temporal fossa
, and gives origin to the Temporalis muscle
.
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
.
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.
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.
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.
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 crest ends below in a small notch which is converted into a foramen, the foramen cecum
, by articulation with the ethmoid.
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
.
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.
Several small, irregular fossæ may also be seen on either side of the sagittal sulcus
, for the reception of the arachnoid granulations.
Squama
Squama refers to a structure shaped like the scale of a fish. More specifically, it can refer to:* Squama frontalis* Squama occipitalis* Squama temporalis, the squamous portion of the temporal bone* Squamous cell...
of the frontal bone
Frontal bone
The frontal bone is a bone in the human skull that resembles a cockleshell in form, and consists of two portions:* a vertical portion, the squama frontalis, corresponding with the region of the forehead....
: the external surface, and the internal surface.
External surface
The external surface 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.On either side of this suture, about 3 cm. above the supraorbital margin, is a rounded elevation, the frontal eminence
Frontal eminence
On the frontal bone, on either side of the frontal suture, about 3 cm. above the supraorbital margin, is a rounded elevation, the frontal eminence ....
(tuber frontale).
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
Galea aponeurotica
The galea aponeurotica is a tough layer of dense fibrous tissue which covers the upper part of the cranium; behind, it is attached, in the interval between its union with the Occipitales, to the external occipital protuberance and highest nuchal lines of the occipital bone; in front, it forms a...
.
Below the frontal eminences, and separated from them by a shallow groove, are two arched elevations, the superciliary arches
Superciliary arches
On the squama frontalis of the frontal bone of the skull, 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.Typically, the...
; these are prominent medially, and are joined to one another by a smooth elevation named the glabella
Glabella
The glabella, in humans, is the space between the eyebrows and above the nose. It is slightly elevated, and joins the two superciliary ridges.-Etymology:The term is derived from the Latin glabellus, meaning smooth, as this area is usually hairless....
. 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; prominent ridges are, however, occasionally associated with small air sinuses.
Beneath each superciliary arch is a curved and prominent margin, the supraorbital margin, which forms the upper boundary of the base of the orbit
Orbit
In physics, an orbit is the gravitationally curved path of an object around a point in space, for example the orbit of a planet around the center of a star system, such as the Solar System...
, and separates the squama from the orbital portion of the bone.
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.
At the junction of its medial and intermediate thirds is a notch, sometimes converted into a foramen, the supraorbital notch
Supraorbital notch
The Supraorbital notch is a small groove at superior and medial margin of the orbit in the frontal bone. The supraorbital nerve passes through this notch prior to dividing into superficial and deep components that provide sensory innervation to the ipsilateral forehead...
or foramen, which transmits the supraorbital vessels and nerve.
A small aperture in the upper part of the notch transmits a vein from the diploë
Diploë
Diploë refers to the spongy bone structure of the internal part of short, irregular, and flat bones.In the cranial bones, the layers of compact tissue are familiarly known as the tables of the skull; the outer one is thick and tough; the inner is thin, dense, and brittle, and hence is termed the...
to join the supraorbital vein
Supraorbital vein
The supraorbital vein begins on the forehead where it communicates with the frontal branch of the superficial temporal vein.It runs downward superficial to the Frontalis muscle, and joins the frontal vein at the medial angle of the orbit to form the angular vein.Previous to its junction with the...
.
The supraorbital margin ends laterally in the zygomatic process
Zygomatic process of frontal bone
The zygomatic process of frontal bone is the part of the zygomatic process consisting of the frontal bone.The supraorbital margin of the frontal bone ends laterally in the zygomatic process, which is strong and prominent, and articulates with the zygomatic bone...
, which is strong and prominent, and articulates with the zygomatic bone
Zygomatic bone
The zygomatic bone is a paired bone of the human skull. It articulates with the maxilla, the temporal bone, the sphenoid bone and the frontal bone. The zygomatic is homologous to the jugal bone of other tetrapods...
.
Running upward and backward from this process is a well-marked line, the temporal line
Temporal line
Crossing the middle of the parietal bone in an arched direction are two curved lines, the superior and inferior temporal lines; the former gives attachment to the temporal fascia, and the latter indicates the upper limit of the muscular origin of the Temporalis.-External links:*...
, which divides into the upper and lower temporal lines, continuous, in the articulated skull, with the corresponding lines on the parietal bone.
The area below and behind the temporal line forms the anterior part of the temporal fossa
Temporal fossa
The temporal fossa is a shallow depression on the side of the skull bounded by the temporal lines and terminating below the level of the zygomatic arch.-Boundaries:...
, and gives origin to the Temporalis muscle
Temporalis muscle
The temporal muscle is one of the muscles of mastication.-Structure:It arises from the temporal fossa and the deep part of temporal fascia...
.
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
Maxilla
The maxilla is a fusion of two bones along the palatal fissure that form the upper jaw. This is similar to the mandible , which is also a fusion of two halves at the mental symphysis. Sometimes The maxilla (plural: maxillae) is a fusion of two bones along the palatal fissure that form the upper...
and with the lacrimal
Lacrimal
The term Lacrimal can refer to:*In typography:** A type of Stroke ending *In anatomy** Lacrimal apparatus** Lacrimal artery** Lacrimal bone...
.
The term nasion
Nasion
The nasion is the intersection of the frontal and two nasal bones of the human skull. Its manifestation on the visible surface of the face is a distinctly depressed area directly between the eyes, just superior to the bridge of the nose....
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.
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.
The spine forms part of the septum
Septum
In anatomy, a septum is a wall, dividing a cavity or structure into smaller ones.-In human anatomy:...
of the nose, articulating in front with the crest of the nasal bones and behind with the perpendicular plate of the ethmoid.
Internal surface
The internal surface of the squamaSquama
Squama refers to a structure shaped like the scale of a fish. More specifically, it can refer to:* Squama frontalis* Squama occipitalis* Squama temporalis, the squamous portion of the temporal bone* Squamous cell...
is concave and presents in the upper part of the middle line a vertical groove, the sagittal sulcus
Sagittal sulcus
The internal surface of the squama frontalis of the frontal bone 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...
, the edges of which unite below to form a ridge, the frontal crest; the sulcus
Sulcus (anatomy)
A sulcus is a depression or fissure in the surface of an organ, especially the brain.-Elsewhere:* anterior interventricular sulcus* calcaneal sulcus* coronal sulcus* gingival sulcus* gluteal sulcus* interlabial sulci...
lodges the superior sagittal sinus, while its margins and the crest afford attachment to the falx cerebri
Falx cerebri
The falx cerebri, also known as the cerebral falx, so named from its sickle-like form, is a strong, arched fold of dura mater which descends vertically in the longitudinal fissure between the cerebral hemispheres....
.
The crest ends below in a small notch which is converted into a foramen, the foramen cecum
Foramen cecum (frontal bone)
The frontal crest of the frontal bone ends below in a small notch which is converted into a foramen, the foramen cecum , by articulation with the ethmoid....
, by articulation with the ethmoid.
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
Superior sagittal sinus
The superior sagittal sinus , within the human head, is an unpaired area along the attached margin of falx cerebri. It allows blood to drain from the lateral aspects of anterior cerebral hemispheres to the confluence of sinuses...
.
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.
Several small, irregular fossæ may also be seen on either side of the sagittal sulcus
Sagittal sulcus
The internal surface of the squama frontalis of the frontal bone 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...
, for the reception of the arachnoid granulations.