Cranial vault development /certified fixed orthodontic courses by Indian dental academy
The development of skull is a blend of the morphogenesis
and growth of three main skull entities.
These skull entities are composed of the following :
The Masticatory Apparatus
comprises of the
Vault of the Skull or
Cranial Base or
Complex) Also known as
Viscerocranium forms the
respiratory aditus and
The Masticatory Apparatus
is composed of the jaw
bones,their joints and
musculature and the teeth.
The cranial base is shared
by both neurocranial &
The masticatory apparatus
is composed of both facial
& dental elements.
Thus skull is a mosaic of
each of which grows to the
proper extent & in the
Three general patterns of development of congenital
craniofacial defects have been observed :
Hypoplastic defects may improve with “catch-up”
growth minimizing the defect.
The defective pattern of growth is maintained
throughout childhood, so that malformation is retained
to some degree in the adult.
The developmental derangement worsens with
age,severity becomes greater in adulthood.
Differentiation & growth of chondrocranium appear to
be strongly genetically determined and subject to
minimal environmental influence.
Growth of desmocranium and splanchnocranium
subject to minimal genetic determination but strongly
influenced by local environmental factors.
The calvaria grows most rapidly in response to early
expanding brain, followed by nasal airway system and
lastly, the masticatory system.
The mesenchyme that gives rise to the vault
of the neurocranium is arranged first as a
capsular membrane around the developing
The membrane is composed of two layers :
Inner Endomeninx (Neural crest origin)
Outer Ectomeninx (Paraxial mesodermal &
Neural crest origin)
The duramater and its septa show
distinctly organized fibre bundles closely
related and strongly attached to the
The adult form of the neurocranium is the
end result of the preferential direction of
the forces set up by growth of the brain.
In somite period embryo,
the neural tube’s
covering duramater and
its surface ectoderm are
of this contact during
development causes a
dural projection, that
extends into the future
As the nasal capsules surround the dural
projection, the resulting midline canal forms
the basis of the Foramen Caecum.
Ossification of the
bones depend upon the
presence of brain.
In its absence, no bony
The condition is known as
Several primary and
secondary ossification centers
develop in the outer layer of
the ectomeninx, to form
It gives rise to major portions
of the Frontal, Parietal,
Sphenoid, Temporal &
Neural Crest provides the
mesenchyme forming the
Lacrimal, Nasal, Zygomatic,
Maxillary and Mandibular
A pair of frontal bones appears from single primary
ossification centers at the 8th week post conception.
Three pairs of secondary centers appear later.
Fusion between these centers is completed at 6 to 7
months post conception.
At birth, frontal bones are separated by frontal or metopic
suture; synostotic fusion of this suture usually starts
about the 2nd year & unites into a single bone by 7 years.
The frontal suture persists into adulthood in 10-15% of
Two parietal bones arise from two primary
ossification centers for each bone that appear in the
parietal eminence in 8th week post conception.
Delayed ossification may result in sagittal fontanelle
The supranuchal squamous portion of the occipital
bone ossifies intramembranously from two centers,
one on each side, appearing the 8th week post
Rest of the occipital bone ossifies endochondrally.
The squamous portion ossifies intramembranously
from a single center appearing at the root of zygoma
at the 8th week post conception.
The tympanic ring ossifies intramembranously from
four centers appearing in the 3rd month after
If any unusual ossification center develop
between the individual calvarial bones, their
independent existence is recognizable as
small sutural or wormian bones.
The earliest centers of ossification first
appear during 7th & 8th weeks post conception,
but ossification is not completed well after
The mesenchyme between the bones
develops fibres to form syndesmotic
At birth, the individual
calvarial bones are
separated by sutures
of variable width &
Six fontanelles are
present : Anterior,
At birth, neurocranium has achieved 25% of
its ultimate growth, completes 50% by 6
months, 75% by 2 years and by 10 years
95% of neurocranial growth is completed.
By 10 years, facial skeleton has achieved
only 65% of its total growth.
In postnatal life, neurocranium increases 4-5
times in volume whereas facial skeleton
increases 8-10 times its volume at birth.
The expanding brain exerts separating tensional
forces upon the bone sutures, thereby secondarily
stimulating sutural bone growth.
The brain acts in this context as a “ Functional
Matrix” in determining the extent of neurocranial
In mid-gestational period (4-5 months), average size
of head is 18cm., which nearly doubles to average of
During the 1st year, it reaches an average of
46cm.and then slows.
Head circumference reaches 49 cm.at 2 years and
only 50 cm.at 3 years.
The increase between the age of 3 years and
adulthood is only about 6 cm.
It is a combination of :
SURFACE APPOSITION & RESORPTION
By 4 years of age, lamellar
compaction of cancellous
trabeculae forms the inner &
outer tables of the cranial
The inner table is primarily
related to brain &
The outer table is more
responsive to extracranial
muscular & buttressing
The two cortical plates are not
The thickening in the region
of glabella results from
separation of inner & outer
tables with the invasion of the
Only external plate is
remodeled, as the internal
plate becomes stable at 6-7
years of age.
Inner aspect of Frontal bone can be used as a
stable reference point from age 7 years
Defects in closure of Foramen Caecum