DOI Page / Citation link:
https://doi.org/10.11588/diglit.6271#0040
( 14 )
OS FRONTIS.
Os Frontale.
The frontal bone is situated in the anterior part of the skull,,
forming the forehead and upper part of the orbits; it is of a
semicircular shape, and when detached from the other bones of
the cranium, has some resemblance to a cockle-shell. Exter-
nally, where it forms the forehead, it is very smooth and
convex ; but below, where it assists in forming the orbit, it
affords several processes and cavities. The inner and concave
surface of this bone is turned towards tire brain, and in the
centre of its inferior part is the ethmoid bone, which is
placed at tire top of the cavity, of the nostrils. It sometimes
consists of two portions, in consequence of the sagittal suture
being continued down through its middle to the nose. This is
more frequent in females than males.
Processes. Two frontal eminences, which mark the centres
of ossification;—two frontal tuberosities, which are situated
over the frontal sinuses;—two superciliary ridges, or archet,.
which give origin to the frontal muscles, and whose extremi-
ties are called the angular or orbiiar processes; behind each
external angular process, the surface of the bone is conside-
rably depressed, for the situation of a part of the temporal
muscle ; this is called the temporal fossa;—an external frontal
spine ; called also the nasal process, upon which the ossa nasi
rest; an internal frontal spine, to which the dura mater ad-
heres ;—and two orbitar plates, which separate the orbits from
the cavity of the cranium.
Cavities. The cerebral cavity, which contains the anterior
portions of the hemispheres of the brain;—a large mtch be-
tween the orbitar plates for the situation of the cribriform
plate of the «ttimoid bone ;—two frontal, or pituitary sinuses
OS FRONTIS.
Os Frontale.
The frontal bone is situated in the anterior part of the skull,,
forming the forehead and upper part of the orbits; it is of a
semicircular shape, and when detached from the other bones of
the cranium, has some resemblance to a cockle-shell. Exter-
nally, where it forms the forehead, it is very smooth and
convex ; but below, where it assists in forming the orbit, it
affords several processes and cavities. The inner and concave
surface of this bone is turned towards tire brain, and in the
centre of its inferior part is the ethmoid bone, which is
placed at tire top of the cavity, of the nostrils. It sometimes
consists of two portions, in consequence of the sagittal suture
being continued down through its middle to the nose. This is
more frequent in females than males.
Processes. Two frontal eminences, which mark the centres
of ossification;—two frontal tuberosities, which are situated
over the frontal sinuses;—two superciliary ridges, or archet,.
which give origin to the frontal muscles, and whose extremi-
ties are called the angular or orbiiar processes; behind each
external angular process, the surface of the bone is conside-
rably depressed, for the situation of a part of the temporal
muscle ; this is called the temporal fossa;—an external frontal
spine ; called also the nasal process, upon which the ossa nasi
rest; an internal frontal spine, to which the dura mater ad-
heres ;—and two orbitar plates, which separate the orbits from
the cavity of the cranium.
Cavities. The cerebral cavity, which contains the anterior
portions of the hemispheres of the brain;—a large mtch be-
tween the orbitar plates for the situation of the cribriform
plate of the «ttimoid bone ;—two frontal, or pituitary sinuses