GENERAL ANATOMY 2
COLLEGE OF DENTISTRY
NORMA VERTICALIS
The top of the skull –the calvarium –presents portions of 4 bones: the frontal bone anteriorly, the
occipital bone posteriorly, and the two parietal bones laterally. It has a broad oval form, rounder but wider
posteriorly and flatter but wider anteriorly.
It presents the following structures:
1. Sagittal suture –interparietal –union of two parietal bones.
2. Coronal suture –fronto-parietal suture.
3. Lambdoid suture –parieto-occipital suture.
4. Lambda –point of union between lambdoidal and sagittal sutures.
5. Bregma –point of union between coronal and sagittal sutures.
6. Vertex –part of sagittal suture indicating the highest point of the skull when held in the proper
position.
7. Parietal eminences –the most convex point of the external surface of each parietal bone.
8. Parietal foramina –minute openings on each side of the sagittal suture just posterior to the
vertex. Maybe unilateral or bilateral. If bilateral, the space between the two parietal eminences is
called “obellion”.
SKULL CAP –vault or roof; concave internally
1. Sutures –sagittal, coronal, lambdoid and squamosal sutures
2. Frontal crest –upward extension of median ridge on lower part of cerebral surface of frontal
bone.
3. Sagittal groove –shallow median furrow on cerebral surface of the vault.
4. Granular pits –several small irregular depressions along the sides of the sagittal groove.
Occupied by Pacchonian bodies.
5. Parietal foramen –small openings on either side of the sagittal sulcus.
6. Cerebral gyri impressions –shallow, ill-defined depressions corresponding to the convolutions of
cerebrum.
7. Vascular grooves –narrow, branching furrows extending from sides of vaults towards the top.
Occupied by meningeal vessels.
, GENERAL ANATOMY 2
COLLEGE OF DENTISTRY
NORMA FRONTALIS
This view of the skull presents an irregular surface with three large excavations: the nasal and two orbital
cavities. It is divided into 6 regions: frontal, orbital, nasal, zygomatic, maxillary and mandibular
regions.
THE FRONTAL REGION
The forehead, formed by the frontal bone. Superiorly, it merges into the top of the skull and inferiorly, it is
limited by the orbits and the root of the nose.
It presents the following features:
1. Frontal tuberosity or eminence –the most convex part of the external surface of each half of the
frontal bone.
2. Superciliary arch –elevation below the frontal tuberosity indicating the positions of the
eyebrows.
3. Nasion –junction the fronto-nasal suture and internasal suture. It is found at the point in the
median plane where the two nasal bones articulate with the frontal bone and is opposite the
anterior extremity of the brain.
4. Glabella –smooth surface where the two superciliary arches meet in the median line; overlying
skin is bald or glabrous.
5. Supraorbital margin –superior boundary of the orbit.
6. Supraorbital notch or foramen –located immediately above the upper border of the orbital
opening at the junction of its medial with its lateral two-thirds. Passageway of blood vessels and
nerves of the same name.
THE ORBITAL REGION
Each orbit is a deep cavity which resembles an irregular cone and may be likened to a pyramid having
four walls, an apex and a base. The bones that form the orbital pyramid are the maxillary, zygomatic,
sphenoid, frontal, palatine, ethmoid and lacrimal. The medial walls are parallel and separated by the nasal
cavity; the lateral walls are at right angle with each other.
Boundaries of the orbit:
1. Apex –posterior convergence of the 4 walls marked by the round opening –the optic foramen
(passageway of optic nerve) bounded by two roots of the lesser wing of sphenoid bone.
2. Base –quadrilateral entrance to the orbital cavity
● Superiorly –frontal bone
● Medially –frontal process of the maxilla
● Inferiorly –maxilla medially and zygomatic bone laterally
● Laterally –zygomatic bone
3. Superior wall or roof –concave, formed by the orbital plane of the frontal bone, completed
posteriorly by lesser wings of sphenoid. It presents the following:
● Fossa of lacrimal gland –a shallow but wide depression found on the supero-lateral
part.
● Trochlear pit or fossa –attachment of the trochlea, a small fibrocartilaginous ring
through which the tendon of the superior oblique muscle passes.
COLLEGE OF DENTISTRY
NORMA VERTICALIS
The top of the skull –the calvarium –presents portions of 4 bones: the frontal bone anteriorly, the
occipital bone posteriorly, and the two parietal bones laterally. It has a broad oval form, rounder but wider
posteriorly and flatter but wider anteriorly.
It presents the following structures:
1. Sagittal suture –interparietal –union of two parietal bones.
2. Coronal suture –fronto-parietal suture.
3. Lambdoid suture –parieto-occipital suture.
4. Lambda –point of union between lambdoidal and sagittal sutures.
5. Bregma –point of union between coronal and sagittal sutures.
6. Vertex –part of sagittal suture indicating the highest point of the skull when held in the proper
position.
7. Parietal eminences –the most convex point of the external surface of each parietal bone.
8. Parietal foramina –minute openings on each side of the sagittal suture just posterior to the
vertex. Maybe unilateral or bilateral. If bilateral, the space between the two parietal eminences is
called “obellion”.
SKULL CAP –vault or roof; concave internally
1. Sutures –sagittal, coronal, lambdoid and squamosal sutures
2. Frontal crest –upward extension of median ridge on lower part of cerebral surface of frontal
bone.
3. Sagittal groove –shallow median furrow on cerebral surface of the vault.
4. Granular pits –several small irregular depressions along the sides of the sagittal groove.
Occupied by Pacchonian bodies.
5. Parietal foramen –small openings on either side of the sagittal sulcus.
6. Cerebral gyri impressions –shallow, ill-defined depressions corresponding to the convolutions of
cerebrum.
7. Vascular grooves –narrow, branching furrows extending from sides of vaults towards the top.
Occupied by meningeal vessels.
, GENERAL ANATOMY 2
COLLEGE OF DENTISTRY
NORMA FRONTALIS
This view of the skull presents an irregular surface with three large excavations: the nasal and two orbital
cavities. It is divided into 6 regions: frontal, orbital, nasal, zygomatic, maxillary and mandibular
regions.
THE FRONTAL REGION
The forehead, formed by the frontal bone. Superiorly, it merges into the top of the skull and inferiorly, it is
limited by the orbits and the root of the nose.
It presents the following features:
1. Frontal tuberosity or eminence –the most convex part of the external surface of each half of the
frontal bone.
2. Superciliary arch –elevation below the frontal tuberosity indicating the positions of the
eyebrows.
3. Nasion –junction the fronto-nasal suture and internasal suture. It is found at the point in the
median plane where the two nasal bones articulate with the frontal bone and is opposite the
anterior extremity of the brain.
4. Glabella –smooth surface where the two superciliary arches meet in the median line; overlying
skin is bald or glabrous.
5. Supraorbital margin –superior boundary of the orbit.
6. Supraorbital notch or foramen –located immediately above the upper border of the orbital
opening at the junction of its medial with its lateral two-thirds. Passageway of blood vessels and
nerves of the same name.
THE ORBITAL REGION
Each orbit is a deep cavity which resembles an irregular cone and may be likened to a pyramid having
four walls, an apex and a base. The bones that form the orbital pyramid are the maxillary, zygomatic,
sphenoid, frontal, palatine, ethmoid and lacrimal. The medial walls are parallel and separated by the nasal
cavity; the lateral walls are at right angle with each other.
Boundaries of the orbit:
1. Apex –posterior convergence of the 4 walls marked by the round opening –the optic foramen
(passageway of optic nerve) bounded by two roots of the lesser wing of sphenoid bone.
2. Base –quadrilateral entrance to the orbital cavity
● Superiorly –frontal bone
● Medially –frontal process of the maxilla
● Inferiorly –maxilla medially and zygomatic bone laterally
● Laterally –zygomatic bone
3. Superior wall or roof –concave, formed by the orbital plane of the frontal bone, completed
posteriorly by lesser wings of sphenoid. It presents the following:
● Fossa of lacrimal gland –a shallow but wide depression found on the supero-lateral
part.
● Trochlear pit or fossa –attachment of the trochlea, a small fibrocartilaginous ring
through which the tendon of the superior oblique muscle passes.
