GENERAL ANATOMY 2
COLLEGE OF DENTISTRY
SKULL
The word “skull” refers to the entire skeleton of the head and the face, including the mandible. “Cranium”
refers to the skull minus the mandible. “Calvarium refers to the skull minus the bones of the face that have
been removed. The skull is composed of a series of flattened and irregular bones, united at immobile
joints called “sutures”; with the exception of the mandible.
The bones of the head enclose the following cavities:
1. Cranial –where the brain is lodged.
2. Orbital –where eyeballs and accessory organs are lodged.
3. Nasal –divided into 2 spaces by the bony nasal septum.
Divisions of the bone in the skull:
A. Cerebral or Cranial bones or Braincase -8 bones.
1. Unpaired -4
a. Occipital –forms the back of the head and posterior floor of the cranial cavity.
b. Frontal –forms the forehead, the roof of the orbit and anterior floor of the cranial cavity.
c. Sphenoid –bat-shaped bone forming the middle floor of the cranial cavity and the back of
the orbit.
d. Ethmoid –found between the cranial, nasal and orbital cavities.
2. Paired -4
a. Parietal –crown –form the roof of the cranial cavity.
b. Temporal –ear region –form the side and floor of the cranial cavity and houses the ear
cavity and the ossicles.
B. Facial or Visceral Cranium -14
1. Paired -12
a. Nasal –form the bridge of the nose.
b. Lacrimal –the most delicate bones of the skull.
c. Maxilla –forms the upper jaw.
d. Zygomatic –malar bone or cheek bone
e. Palatine –L-shaped bone forming the posterior part of the hard palate.
f. Inferior Nasal Conchae –scroll-like bones found in the lateral walls of the nasal cavity.
2. Unpaired -2
a. Vomer –flat bone that forms the lower part of the bony nasal septum.
b. Mandible –forms the lower jaw; the biggest and the only moving bone of the skull.
The skull as a whole is slightly flattened from side to side. Viewed from above, it is smooth; while viewed
from below, it is very uneven. It is oval in shape, wider behind than in front, and is composed of irregular
and flat bones (made up of 2 layers of compact bones –outer layer is thick and tough –called the outer
table while the inner layer is thinner and more brittle called the inner table enclosing a layer of spongy
bone called diploe). The base of the skull is much thicker and stronger. It presents a number of openings
called foramina for the passage of spinal cord, the cranial nerves and blood vessels.
, GENERAL ANATOMY 2
COLLEGE OF DENTISTRY
The bones of the skull develop in early fetal life. Ossification is not complete at birth, hence,
membrane-filled spaces called “fontanels” are found between the bones. These are important for the
development of brain case. Closure indicates that bone ossification is completed while non-closure
indicates incomplete bone formation. The membranous tissue between the cranial bones at the sutures and
fontanels allow certain degrees of overlapping during birth processes, thus reducing the diameter of the
baby’s skull, a process called “molding”.
Fontanels found in the newborn baby’s skull:
1. Anterior or Bregmatic –largest, situated between the frontal and parietal bones. It closes
completely by the second year of life (18-24 months).
2. Posterior or Occipital –triangular gap between the occipital and parietal bones. It closes
completely two months after birth.
3. Sagittal fontanel –found along the sagittal suture in the region of parietal foramina or obellion. It
may be closed already at birth.
4. Antero-lateral or sphenoidal –found in the antero-inferior angles of parietal bones. It closes three
months after birth.
5. Postero-lateral or mastoidal –found at the postero-inferior angles of parietal bones. It is
completely closed by the first year of life.
MICROCEPHALY –small skull caused by early closure of the fontanels.
MACROCEPHALY –big skull caused by delayed closure of the fontanels.
HYDROCEPHALUS –characterized by increased intracranial pressure due to excessive amount of
cerebrospinal fluid inside the brain causing the fontanels to remain open. It is usually fatal if uncorrected
or with mental and physical retardation if the child survived.
Nomenclature of Sutures: according to the bones that they unite’ except:
1. Coronal or Fronto-Parietal Suture
2. Sagittal or Parieto-Parietal Suture
3. Lambdoid or Occipito-Parietal Suture
Classification of Sutures:
1. True or Sutura Vera –the articulating surfaces are smooth.
● Sutura dentate –tooth-like appearance.
➔ Ex. Sagittal suture
● Sutura serrate –saw-like; finer than sutura dentate.
➔ Ex. Zygomatico-maxillary suture
● Sutura limbosa –articulating bones overlap with one another.
➔ Ex. Coronal suture
2. False or Sutura Notha –articulating surfaces are rough.
● Sutura squamosal –scale-like appearance of articulating surfaces.
➔ Ex. Temporo-parietal suture or squamosal suture
● Sutura harmonia –simple apposition of articulating parts or surface; may also be
overlapping without definite shape.
➔ Ex. Internasal suture
COLLEGE OF DENTISTRY
SKULL
The word “skull” refers to the entire skeleton of the head and the face, including the mandible. “Cranium”
refers to the skull minus the mandible. “Calvarium refers to the skull minus the bones of the face that have
been removed. The skull is composed of a series of flattened and irregular bones, united at immobile
joints called “sutures”; with the exception of the mandible.
The bones of the head enclose the following cavities:
1. Cranial –where the brain is lodged.
2. Orbital –where eyeballs and accessory organs are lodged.
3. Nasal –divided into 2 spaces by the bony nasal septum.
Divisions of the bone in the skull:
A. Cerebral or Cranial bones or Braincase -8 bones.
1. Unpaired -4
a. Occipital –forms the back of the head and posterior floor of the cranial cavity.
b. Frontal –forms the forehead, the roof of the orbit and anterior floor of the cranial cavity.
c. Sphenoid –bat-shaped bone forming the middle floor of the cranial cavity and the back of
the orbit.
d. Ethmoid –found between the cranial, nasal and orbital cavities.
2. Paired -4
a. Parietal –crown –form the roof of the cranial cavity.
b. Temporal –ear region –form the side and floor of the cranial cavity and houses the ear
cavity and the ossicles.
B. Facial or Visceral Cranium -14
1. Paired -12
a. Nasal –form the bridge of the nose.
b. Lacrimal –the most delicate bones of the skull.
c. Maxilla –forms the upper jaw.
d. Zygomatic –malar bone or cheek bone
e. Palatine –L-shaped bone forming the posterior part of the hard palate.
f. Inferior Nasal Conchae –scroll-like bones found in the lateral walls of the nasal cavity.
2. Unpaired -2
a. Vomer –flat bone that forms the lower part of the bony nasal septum.
b. Mandible –forms the lower jaw; the biggest and the only moving bone of the skull.
The skull as a whole is slightly flattened from side to side. Viewed from above, it is smooth; while viewed
from below, it is very uneven. It is oval in shape, wider behind than in front, and is composed of irregular
and flat bones (made up of 2 layers of compact bones –outer layer is thick and tough –called the outer
table while the inner layer is thinner and more brittle called the inner table enclosing a layer of spongy
bone called diploe). The base of the skull is much thicker and stronger. It presents a number of openings
called foramina for the passage of spinal cord, the cranial nerves and blood vessels.
, GENERAL ANATOMY 2
COLLEGE OF DENTISTRY
The bones of the skull develop in early fetal life. Ossification is not complete at birth, hence,
membrane-filled spaces called “fontanels” are found between the bones. These are important for the
development of brain case. Closure indicates that bone ossification is completed while non-closure
indicates incomplete bone formation. The membranous tissue between the cranial bones at the sutures and
fontanels allow certain degrees of overlapping during birth processes, thus reducing the diameter of the
baby’s skull, a process called “molding”.
Fontanels found in the newborn baby’s skull:
1. Anterior or Bregmatic –largest, situated between the frontal and parietal bones. It closes
completely by the second year of life (18-24 months).
2. Posterior or Occipital –triangular gap between the occipital and parietal bones. It closes
completely two months after birth.
3. Sagittal fontanel –found along the sagittal suture in the region of parietal foramina or obellion. It
may be closed already at birth.
4. Antero-lateral or sphenoidal –found in the antero-inferior angles of parietal bones. It closes three
months after birth.
5. Postero-lateral or mastoidal –found at the postero-inferior angles of parietal bones. It is
completely closed by the first year of life.
MICROCEPHALY –small skull caused by early closure of the fontanels.
MACROCEPHALY –big skull caused by delayed closure of the fontanels.
HYDROCEPHALUS –characterized by increased intracranial pressure due to excessive amount of
cerebrospinal fluid inside the brain causing the fontanels to remain open. It is usually fatal if uncorrected
or with mental and physical retardation if the child survived.
Nomenclature of Sutures: according to the bones that they unite’ except:
1. Coronal or Fronto-Parietal Suture
2. Sagittal or Parieto-Parietal Suture
3. Lambdoid or Occipito-Parietal Suture
Classification of Sutures:
1. True or Sutura Vera –the articulating surfaces are smooth.
● Sutura dentate –tooth-like appearance.
➔ Ex. Sagittal suture
● Sutura serrate –saw-like; finer than sutura dentate.
➔ Ex. Zygomatico-maxillary suture
● Sutura limbosa –articulating bones overlap with one another.
➔ Ex. Coronal suture
2. False or Sutura Notha –articulating surfaces are rough.
● Sutura squamosal –scale-like appearance of articulating surfaces.
➔ Ex. Temporo-parietal suture or squamosal suture
● Sutura harmonia –simple apposition of articulating parts or surface; may also be
overlapping without definite shape.
➔ Ex. Internasal suture
