GROWTH & DEVELOPMENT OF CRANIAL VAULT & BASE
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Skull
ď Ž
At Birth- 45 bony elements
 In Adult- 22 bones Face- 14 bones Cranium- 8 bones www.indiandentalacademy.com
Cranium ď Ž
ď Ž
Paired:- 1. parietal 2. temporal Unpaired 1. frontal 2. occipital 3. sphenoid 4. ethmoid
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Four regions of the Craniofacial complex
The Cranial Vault The Cranial Base The Naso-maxillary complex The Mandible
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Further – Pre - natal and Post - natal growth Attention to:1. Site and location of growth 2. Type of growth occurring. 3. Determinant or controlling factors.
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Anatomy
Norma Verticalis – Above
Norma Basalis – Below
Norma Lateralis – Side
Norma Occipitalis – Back
Norma Frontalis - Front
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Span – Superciliary ridges & glabella of frontal bone upto & including Squamous occipital bone. Also includes part of Squamous temporal bone laterally.
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When viewed from above:a Ellipsoidal (roughly) b Bones – Frontal Parietal Occipital Temporal Greater wing of sphenoid www.indiandentalacademy.com
c. Sutures Frontal (metopic) Coronal Sagittal Lambdoid Bregma Lambda
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Neurocranium
Vault of skull(calvaria)
Phylogenetically-recent origin, to cover the newly expanded brain.
Formation- intramembranous bone of paraxial mesodermal & neural crest origin
Known a desmocranium.
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Cranial base
Derived phylogenetically –ancient cranial floor.
Associated with the capsular investments of nasal & auditory sense organs.
Neural crest origin.
Cartilaginous precursor-chondrocranium.
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Development of calvaria Pre-natal growth Endomenix Ectomeninx
Arachnoid Piamater Skull bone Duramater
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Ossification centers of the skull Mesoderm – Frontal, Parietal, sphenoid, petrous temporal & occipital. Neural crest – Lacrimal, nasal, squamous temporal, zygomatic, maxilla & mandible
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Ossification centers of the skull
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Pre-Natal Growth
Frontal Bone
Primary centre ------ Superciliary arch(8 th wk)
Secondary centers ------ zygomatic process, (fusion 6-7 mts)
nasal spine, trochlear fossae
At birth- Metopic suture, fusion 2-7yrs www.indiandentalacademy.com
Pre-Natal Growth
Parietal bone
Occipital bone (Squamous part) 8th wk
Region of Parietal eminence 8th wk, fuse by 4th month. Just above superior nuchal line
Temporal bone (Squamous part)
Root of zygoma www.indiandentalacademy.com
Frontanellae ď Ž
ď Ž
Flat bones connected by loose connective tissue. Close at various times- 3 months to 2 years.
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Fontenallae
Time of closure
-Anterior
-2nd year
-posterior
-2 mts
-Ant lateral
-3mts
-Post lateral
-2nd year www.indiandentalacademy.com
Pre-Natal Growth -Control
Intrinsic genetic factors
Epigenetic factors
Environmental factors
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Intrinsic Genetic control Local epigenetic factors
Cranial Cranial differentiation differentiation
General epigenetic factors Local Environmental factors General Environmental factors
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Pre-Natal Growth -Control Shift of belief:Genetic influence
Epigenetics
Examples- Primordia of eye. - Brain. www.indiandentalacademy.com
Intrinsic Genetic control Local epigenetic factors
Cranial Cranial differentiation differentiation
General epigenetic factors Local Environmental factors General Environmental factors
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Post-Natal Growth Various Theories of Growth, and how they relate to the cranial vault. Sicher’s Sutural dominance theory Scott’s Cartilaginous theory Moss’ FMH
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Sutural Theory
Genetically
determined
Growth at sutures Mild effect of local factors ex- remodeling under the influence of muscles.
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Sichers Theory Intrinsic Genetic control Local epigenetic factors
Desmocranial Desmocranial Growth Growth
General epigenetic factors Local Environmental factors General Environmental factors
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Cartilagenous theory
Intrinsic growth controlling factors – cartilage,periosteum. Sutures-secondary, dependent on extra skeletal influence. Cartilage-primary centers of growth. Nasal septum-major contributor in maxillary growth. www.indiandentalacademy.com
Post-Natal Growth Intrinsic Genetic control
Chondrocranial Chondrocranial Growth Growth
Local epigenetic factors General epigenetic factors
Desmo- Sutures cranial Periosteal Growth growth
Local Environmental factors General Environmental factors www.indiandentalacademy.com
Post-Natal Growth Moss’ FMH
Intrinsic Genetic control Local epigenetic factors
Desmocranial Desmocranial Growth Growth
General epigenetic factors Local Environmental factors General Environmental factors www.indiandentalacademy.com
Post-Natal Growth Moss’ explanation for brain growth controlling growth of the cranium‌ Hydrocephalus, synostosis
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Van Limborgh's Summarization:1.
Intrinsic control of growth at synchondroses
2.
Intrinsic control of sutural growth is less
3.
Synchondroses
4.
Sutural growth controlled in part by growth of cranial base
Growth centre
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5. Periosteal bone growth (vault) controlled epigenetically by adjacent structures 6. Growth of cranial vault also controlled by local environmental factors (muscle forces inclusive)
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Post-Natal Growth Growth of the cranial vault – direct influence of Neurocranial capsule
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As brain expands seperate bones of calvariadisplaced outwardly. Passive movement. Each separate bone is enmeshed within connective tissue stroma.
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Primary displacement- tension in sutural membranes.
Response-new bone deposition-sutural edges.
Each separate bone enlarges-circumference.
Endosteal surfaces-resorptive, overall thickness &expands medullary spaces.
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Post-Natal Growth Thickening not uniform:Inner table Brain Outer table
mechanical influences and functional stresses
Growth of the frontal sinus (Benninghoff)
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Post-Natal Growth 90% of cranial vault growth complete by 5-6 yrs In accordance with -Scammon’s curve - Cephalocaudal Gradient.
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Clinical implications
Altered time closure of sutures-variable distortions of skull shape. Delayed midline ossification of frontal & sagital sutures –anterior frontanelle may remaine open. Cretinism,progeria,trisomy 21,cleidocranial dysostosis. Premature synostosis – Apert syndrome & crouzen syndrome.
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Conditions like hydrocephaly, microcephaly. Abnormal external forces during developmentdistort cranial morphology-bizzare shapes of skulls . Defect in closure of foramen caecum at the ethmoid-frontal suture herniation of cranial content into the facefrontal encephaloceles.
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ď Ž 1. 2. 3.
Cranial growth is a combination of Sutural growth Surface deposition & resorption Centrifugal displacement by the expanding brain.
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GROWTH & DEVELOPMENT OF CRANIAL BASE
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Cranial Base ď Ž
ď Ž
Reasonably stable reference structure in cephalometric analysis Basis to compare and understand abnormal growth patterns
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Functions
Supports & protects the brain & spinal cord
Articulation of skull with vertebral column , mandible & maxilla
Buffer zone between the brain, face & pharyngeal region www.indiandentalacademy.com
Anatomy
Anterior cranial fossa
Middle cranial fossa
Posterior cranial fossa
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Anterior cranial fossa 1. 2. 3.
Orbital part of frontal bone Cribriform plate of ethmoid Anterior part of the body of sphenoid & lesser wing
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Middle cranial fossa It is deeper than the anterior fossa ď Ž
It shaped like a butterfly. In front it is bounded by posterior borders of the lesser wing of sphenoid and the body of the sphenoid,
ď Ž
Behind by superior borders of the temporal bones & Dorsum sellae of sphenoid bone www.indiandentalacademy.com
Middle cranial fossa Centrally Optic Canal Hypophyseal Fossa Laterally Superior Orbital Fissure Foramen Rotundum Foramen Ovale Foramen Spinosum Foramen Lacerum www.indiandentalacademy.com
Middle cranial fossa
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Posterior cranial fossa
Largest and deepest of the cranial fossa.
Sorrounded by dorsum cella, posterior part of body of sphenoid bone & basilar part of occipital bone- anterior.
Posterior- lower portion of squamous part of occipital bone.
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Posterior cranial fossa
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Posterior cranial fossa Various foramina Foramen magnum Jugular foramen Internal acoustic meatus Facial canal Hypoglossal canal
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Pre-natal growth Cranium
 Neurocranium-protects, supports;brain, sense organs
Viscerocranium-alimentary, respiratory tracts, face, maxilla & mandible
Basicranium - both www.indiandentalacademy.com
Prenatal growth Chodrification
Mesenchyme derived from paraxial mesoderm and neural crest .
Form ectomeningeal capsule.
Earliest evidence of skull formation. Mesenchyme starts converting into Cartilage Starting on day 40 i.u. Cartilage www.indiandentalacademy.com
cartilages
parachordal cartilage
Hypophyseal cartilage
Otic capsule.
Nasal capsule
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Parachordal cartilage ď Ž
Chondrification centers forming around the cranial end of the notochord
ď Ž
Parachordal cartilages fuse with the sclerotomes arising from occipital somites surrounding the neural tube
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Parachordal cartilage
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Hypophyseal cartilage 2 Hypophyseal cartilages - Post sphenoid Sella turcica Body of the sphenoid (post. Part)
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2 Pre sphenoid cartilage- Pre sphenoid bone Body of the sphenoid bone (ant. Part)
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Most anteriorly- presphenoid cartilagesMesethmoid Ossifies into perpendicular plate of ethmoid Upper edge forms crista galli
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Orbito sphenoid Lesser wing Alisphenoid Greater wing
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Otic capsule Mastoid and petrous portions of the temporal bones Otic capsule does not chondrify.
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Nasal capsule- 2nd month i.u Cartilages of nostrils and the nasal septal cartilage
Functional matrix- downward & forward growth
Transfer’s compressive forces from incisor region to the sphenoid region
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Primordial cartilage
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Chondrocranial ossification 110 ossification centers –embryonic human skull. Ossification starts in the 4 months. Unossified chondrocranial remnents: Alae & septum of the nose Spheno-occipital & spheno-petrous junctions. Apex of the petrous bone Between the separate parts of occipital bone.
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Chondrocranial ossification
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Occipital bone
7 ossification centers - 2 intramembranous 5 endochondral
Sq portion above sup nuchal line –ossify from pair of i.m ossi centers 8th i.u week
Infranuchally – pair of endochondral centers 10th i.u week www.indiandentalacademy.com
ď Ž
Single median endochondral ossi center at 11 th week ant to foramen magnum & ant 3rd occipital condyle.
ď Ž
pair of endochondral ossification centers at 12 th week from exoccipital bone lateral to magnum including 2/3rd occi condyle.
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Temporal bone
21 ossi centers squamous & tympanic portion – ossify i.m Petrosal & styloid elements - endochondrally
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Sq portion – single center at 8th i.u week.
Tympanic ring- 4 centers at 3rd i.u month.
Petrosal part- 14 centers; appear at 16 th week, fuse 6th i.u month
Styloid process- 2 centers upper center- just before birth lower center- just after birth
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Ethmoid bone – 3 centres A single median center -Perpendicular plate & crista galli
Lateral labyrinths in the nasal cartilages- 2 endochondral centers
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Ossification-sphenoid bone Intramembranous ossification centres Medial pterygoid plates – 2
Lateral pterygoid plates -2
Endochondral ossification centres Presphenoid – 3 Postsphenoid – 4 Orbitosphenoids - 2 Alisphenoids - 2 Pterygoid hamuli -2 www.indiandentalacademy.com
Ossification Bone
Site & number of ossification Intramembranous
Occipital -
supra nuchal squamous (2)
Temporal -
squamous (1) tympanic (4)
Ethmoid -
-
Endochondral infra nuchal squamous(2) Basilar (1) Exoccipital (2) petrosal (14) styloid (2) lateral labarynths (2) perpendicular plate; crista (1)
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Bone
Site & number of ossification Intramembranous
Vomer Sphenoid -
Endochondral
Alae (2) Medial pterygoid pre sphenoid (3) plates (2)
post sphenoid (4)
Lateral pterygoid orbitosphenoid (2) plates (2) elisphenoids (2) pterygoid hamulus (2) sphenoidal conchae( 2)
Inferior nasal conchae www.indiandentalacademy.com
lamina (1)
Cranial base angulation Angle at the hypophyseal fossa where prechordal & chordal parts meet each other
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Highly Uneven
Anterior cranial base increases its length and width by 7 folds between the 10th and 40thweek of I.U life
Posterior cranial base grows only 5 fold
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Post natal growth Expansion of cranial base occurs by ď Ž
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Growth of the cartilage remnants of the chondrocranium- basicranial bones Forces from growing brain
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ď Ž
Cranial base acts as a template from which the face develops
ď Ž
The endocranial surface of the basicranium is resorptive in most areas
ď Ž
Remodeling is required to accommodate the massively enlarged human brain
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Fossa enlargement
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Bony elevations b/w fossae, divide fossa into various compartments
Middle & post fossae by petrous
elevation Olfactory fossae by crista galli Rt & left mid cranial fossae by midline sphenoidal elevation Rt & left ant & post cranial fossae by longi midline bony ridge www.indiandentalacademy.com
Fossa expands outward by resorption, Partitions between them enlarge inward by deposition
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synchondrosis
Bands of cartilage remain at the junction of various bones. Regarded as growth center & pacemaker of cranial base. Present in midline part of basicranium
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Synchondrosis at the base
Spheno-occipital synchondrosis Inter-sphenoidal synchondrosis Spheno-ethmoidal synchondrosis Intra-occipital synchondrosis www.indiandentalacademy.com
Synchondrosis of cranial base
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Spheno-occipital synchondrosis
Major contributor in the post natal growth. Fuses at 12 to 13 years in girls & 14 to 15 years in boys. Ossifies at 20 years of age. Pressure adapted bone growth mechanism.
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Structure of synchondrosis Zones of cartilage Familiar reserve zone Cell division zone Hypertropic zone Calcified zone
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Endochondral bone growth – primary displacement of bones involved. Sphenoid & occipital bones moved apartprimary displacement processes
Two major directions of linear growth
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Hunter-Enlow growth equivalents concept
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ď Ž
Frontal lobe growth completes by 5years.
ď Ž
Temporal lobes continue to enlarge for several more years and displaces the frontal lobe forward. www.indiandentalacademy.com
Clinical implications Configuration of neurocranium(& brain) determines a person’s head form type - Dolicocephalic - Brachycephalic - Mesocephalic
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Cranial base growth for Dutch boys and girls – Monique Henneberke & Birte Prahl Andersen (AJO 1994 ) Hypothesis that there is no difference in the cranial base growth between children with or
without ortho treatment- was tested S-N 153(boys)and 167 (girls) N-Ba and S-Ba 116 (boys) and 116 (girls), 714 yrs Mixed longitudinal study www.indiandentalacademy.com
Results 1.
The effect of orthodontic therapy on cranial base was not significant
2.
The cranial base displayed sexual dimorphism in absolute size, timing and amount of growth.
3.
Girls did not show growth spurts where as boys showed growth spurts for S-N and NBa. www.indiandentalacademy.com
Achondroplasia
Deficient growth at synchondrosis.
Disturbance in endochondral bone formation
Maxilla is not translated forward
This results in abnormal depression of the bridge of the nose
Relative midface deficiency
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ď Ž
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Premature ossification or synostosis of the suture between the presphaenoid and postsphenoid parts of the spheno-occipital suture depressed nasal bridge and dished face
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Anomalous development of the presphenoidal elements Excessive separation of orbits and abnormally broad nasal bridge Hypertelorism
Anecephaly (Absence of calvaria ) Retain acute cranial base flexure
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Cliedocranial disostosis
Abnormalities of the skull, teeth, jaws and shoulder girdle
Afflictions of cartilage growth cranial base with angulation-achondroplasia ,critinism, down’s syndrome
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REFERENCES 1. Craniofacial Embryology G.H.SPERBER 2. Essencials Of Facial Growth D.H.ENLOW 3. Contemporary orthodontics W.R.PROFFIT 4. Orthodontics principles and practice T.M. GRABER 5. Anatomy –Gray www.indiandentalacademy.com
6. Cranial Base Growth For Dutch Boys & Girls – M.Herneberke,b.P. Andersen (AjoNovember; 1994 )
7. Grants Atlas
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