GROWTH AND DEVELOPMENT OF CRANIUM
Introduction Bone growth Synchondroses Sutures Prenatal growth of cranium Cranium at birth Postnatal growth of cranium Theories of growth Anomalies of development Clinical significance Conclusion www.indiandentalacademy.com
Robert E Moyer's has defined growth as normal changes occurring in amount of the living substances. According to him, growth is the quantitative aspect of biologic development.
Development: It refers to all the naturally
occurring unidirectional changes in the life of an individual from its existence as a single cell to its elaborations as a multifunctional unit terminating to death.
We can put this in the formula of Development growth + differentiation + translocation.
Differentiation: it is the change for generalized cells or tissues to more specialized kinds during development and translocation in change in position.
According to Todd – Growth is an increase in
size and development is progress towards maturity According to J.S. Huxley – Growth is self-
multiplication of living substance. According to Krogmen – Growth is increase
in size, change in proportion and progressive complexity. www.indiandentalacademy.com
At the time of birth there are 45 bony elements
separated by cartilage. At the end of one year, it is decreased to 22 after the completion of ossification. 14 of these bones are in the face and the remaining 8 form the cranium. The reduction in the number is due to growth and union at various sutures and endochondral junctions. At the time of birth, the cranium is 8-9 times larger than the facial portion.
Within one year it becomes twice the size of face Development of skull, comprising both the cranium and mandible, is a blend of morphogenesis and the growth of 3 main skull entities arising from â†’ neural crest and â†’paraxial mesoderm tissues www.indiandentalacademy.com
Skull entities is composed of Neurocranium Calvaria (desmocranium) Cranial base (Chondrocranium) Face Masticatory apparatus.
Before we study the growth of the various parts of craniofacial complex, it is important to know how the bone grows. Bone is always connective tissue
The terms cartilaginous or endochondral and membranous or intramembranous identify the type of connective tissue. www.indiandentalacademy.com
Bone is composed of two entities - Osteocytes Intercellular substance Osteocytes are two types Osteoblasts – bone forming cells Osteoclasts – bone resorbing cells.
Endochondral bone formation At the site where the bone is to be formed, the mesenchymal cells become closely packed to form a mesenchymal condensation. Some mesenchymal cells become chondroblasts and lay down hyaline cartilage. Mesenchymal cells on the surface of the cartilage form a membrane called the perichondrium. This membrane is vascular and contains osteogenic cells. www.indiandentalacademy.com
The cells of the cartilage are at first small and irregularly arranged.. however in the area where bone formation is to begin, the cells enlarge considerably. The intercellular substance between the enlarged cartilage cells becomes calcified under the influence of an enzyme called alkaline phosphatase, which secreted by the cartilage cells. The nutrition to the cells is thus cut off and they die, leaving behind empty spaces called primary areolae. www.indiandentalacademy.com
Some blood vessels of the perichondrium now invade the calcified cartilaginous matrix. They are accompanied by osteogenic cells. This mass of vessels and cells is called the periosteal bud. It eats away much of the calcified matrix forming the walls of the primary areolae, and thus creates large cavities called secondary areolae. Thus formation of cartilaginous model takes place. www.indiandentalacademy.com
The walls of the secondary areolae are formed by thin layers of calcified matrix that have not been dissolved. The osteogenic cells become osteoblasts and arrange themselves along the surfaces of these bars, or plates, of calcified cartilaginous matrix.
INTRAMEMBRANOUS OSSIFICATION These osteoblasts now lay down a layer of ossein fibrils embedded in a gelatinous intercellular matrix. This material is called osteoid. It is calcified and a lamellus of bone is formed. The osteoblasts now lay down another layer of osteoid over the first lamellus. This is also calcified. Thus two lamellae of bone are formed. Some osteoblasts that get caught between the lamellae form osteocytes. As more lamellae are laid down, bony trabeculae are formed. www.indiandentalacademy.com
The cartilage junctions between two bones are called synchondroses. They are important growth sites cranial base. www.indiandentalacademy.com
Synchondroses found in cranial base are 1. Spheno - occipital 2. spheno â€“ ethmoidal 3. inter- sphenoidal 4. intra- occipital
Spheno- occipital â€“ it is the cartilaginous junction between the sphenoid and the occipital bones. It is active up to the age of 12-15 years. The sphenoid and the occipital segments then become fused in the midline area by 20 years of age. spheno- ethmoid - this is a cartilaginous band between the sphenoid and ethmoid bones. It ossifies at 8 to 25 years of age
Inter sphenoid - it is a cartilaginous band between the 2 parts of the sphenoid bone. It is believed to ossify at birth. Intra occipital: - this ossifies by 35 years of age. www.indiandentalacademy.com
They are fibrous joints comprised of sheets of dense connective tissue that separate the bones of calvaria The sutures help the calvaria to change shape during birth www.indiandentalacademy.com
Types of sutures 1.
coronal sutures - it is present between posterior border of frontal bone and anterior border of parietal bone Saggital sutures - it is present between upper borders of parietal bones in the median plane lambdoid sutures â€“ it is present between posterior borders of parietal bones and upper border of occipital bone parieto mastoid stutures - it is present between free upper border of mastoid part of temporal bone and posterior part of parietal bone. occipito mastoid sutures â€“ it is present between posterior border of mastoid part of temporal bone and squamous part of occipital bone. www.indiandentalacademy.com
PRENATAL GROWTH OF CRANIUM www.indiandentalacademy.com
Cranial base growth is due to proliferation of cartilage and its replacement by bone, primarily at synchodroses. Cranial vault or desmocranium growth is accomplished by proliferation of connective tissue between the sutures and its replacement by bone. The periosteum also grows, but it is a limiting membrane determining the size and shape changes. Despite the rapid ossification of the cranial vault in the terminal stages of fetal life, the bones of desmocranium are separated from each other by the fontanels when the child is born. www.indiandentalacademy.com
CRANIUM AT BIRTH www.indiandentalacademy.com
At birth, bones of face and jaws are underdeveloped The ratio between cranium and face is 8:1 at birth, later the ratio decreases to 2:1 in the adult. Bones of cranial vault do not complete their growth during fetal life. The point where more than 2 bones meet the sutures are wide open are called Fontanelle (soft spots). Fontanelle are regions of dense connective tissue where sutures joins. www.indiandentalacademy.com
Types of Fontanelle Anterior Fontanelle It is the largest It is seen at the junction of sagittal, coronal and frontal suture. It is diamond shaped. It ossifies between 1 Â˝ to 2 years of age posterior
Posterior Fontanelle It is triangular in shape and located at the function of sagittal and lambdoid suture. It ossifies 2 to 3 months after birth www.indiandentalacademy.com
Antero lateral Fontanelle (Sphenoidal) 2 pairs It ossifies 2 to 3 month after birth Postero lateral Fontanelle (Mastoid) 2 pairs Ossifies at 1 to 2 year of birth
Postnatal growth Of cranium www.indiandentalacademy.com
It is divided into Brain case Cranial base.
Growth of cranial base Cranial base grows by cartilage growth in the sphenoethmoidal, inter sphenoethmoidal, spheno occipital, and intra occipital synchondroses. It follows a neural growth curve, but partially the general growth curve. Activity at the inter sphenoidal synchondroses disappears at birth. Intra occipital synchondrosis closes in the third to fifth year of life. Spheno occipital synchondrosis is a major contributor. Endochondral ossification does not stop here until twentieth year of life. www.indiandentalacademy.com
Growth of brain case The cranium grows because the brain grows. By the end of fifth year of life, over 90% of the growth of the brain capsule or brain vault has been achieved. This increased in size is achieved by proliferation and ossification of sutural connective tissue and by appositional growth of individual bones that make up the cranial vault. Apposition can be seen on both the internal and external tables of the cranial bones as they become thicker. . www.indiandentalacademy.com
The cranial vault increases in width by â€œfill inâ€? ossification of proliferating connective tissues in the coronal lambdoidal, interparetal, parieto shpenoidal and parictotemporal sutures. The mid sagittal sutures between the parietal bones does not close until the middle of the 3rd decade of life. Increase in length of brain may be primarily due to the growth of cranial base with active response at the coronal suture. The brain case grows in height with active response at parietal sutures along with the occipital, temporal, and sphenoidal contiguous osseous structures www.indiandentalacademy.com
CHONDROCRANIAL OSSIFICATION Approximately 110 ossification centers appear in the embryonic human skull. Many of these centers fuse to produce 45 bones in the neonatal skull. In the young adult, 22 skull bones are recognized.
Cartilage Dominance theory â€“ By James Scott, According to the theory the genetic control is expressed at cartilage Scott said that the cartilaginous sites through out the skull are primary growth centers. The nasal septal cartilage is the pacemaker for growth of the entire nasomaxillary complex. The mandible is considered as a long bone bent into a horseshoe shape with the epiphysis removed, so that the cartilage contributes help and epiphyseal plate at the ends, which are represented by condyles. www.indiandentalacademy.com
FUNCTIONAL MATRIX THEORY â€“ BY MELVIN MOSS, 1960, 1962, 1997 Mossâ€™s idea of growth control is that the growth control lies in adjacent soft tissues and cartilage bones are just sites. The growth of the face occurs as a response to functional needs and is mediated by the soft tissues conceptually the soft tissues growth, bone, and cartilage reacts to it. A number of relatively independent functions are carried out in the craniofacial regions or the human body like, respiration, olfaction, vision, hearing, balance, chewing digestion, swallowing speech and neural integration. www.indiandentalacademy.com
Functional cranial components Skeletal Unit â€“ Micro skeletal, Macro skeletal Unit
Functional Matrices Capsular Matrices Periosteal Matrices www.indiandentalacademy.com
The skeletal tissues associated with a single function are called â€œthe skeletal unitâ€?. It is comprises of bone, cartilage and tendinous tissues.
functional matrix The consists of muscles, glands, nerves, vessels, fat, teeth and the functional spaces
Periosteal matrix Their action is directly and actively upon the related skeletal units, alternations in their functional demands produce a secondary compensatory translation of size or shape of their skeletal units. Such processes are brought about by the inter related process of bone deposition and resorption eg. Muscles, blood vessels, nerves glands etc. www.indiandentalacademy.com
Capsular Matrix They act directly and passively on their related skeletal units producing secondary compensatory translation in space. These alterations in spatial position of skeletal units are brought by expansion of the orofacial capsule within which the facial bones arise, grow and are maintained. The facial skeletal units are passively and secondarily moved in space as their enveloping capsule is expanded. Deposition and resorption do not bring about this kind of translative growth. The neurocranial capsule and the oro-facial capsule are examples of capsular matrices. Each of the capsules is an envelope, which contains a series of functional cranial components (skeletal units), which as a whole are sandwiched in between two covering layers. www.indiandentalacademy.com
In Neuro cranial capsule, the cover is skin and duramater and in oro-facial capsule, the skin and mucosa forms the covering. The neurocranial capsule surrounds and protects the neurocranial capsular functional matrix, which is the brain, leptomeninges and CSF. www.indiandentalacademy.com
The neuro cranial capsule is made up of skin,connective tissue aponeurotic layer; loose connective layer, periosteum, base of skull and layers of duramater
The orofacial capsule surrounds and protects the oro-naso-pharyngeal spaces, which constitute the matrix. The growth of the facial skull is influenced by the volume and potency of the spaces. www.indiandentalacademy.com
Van Limborgh’s theory, 1970 Limborgh explains the process of growth and development in the view that combines all the major theories. He supports the Moss’s functional Matrix Theory Acknowledges certain concepts of Sicher’s Theory Never did he rule out the genetic theory.
Unloaded Nerve theory â€“ by Melvin Moss The skeletal units and growth field fulfills the demands for protection of the mandibular nerve by formation of bone around .
Sero system theory – By petrovic and stutzmann 1980 the theory states that the influence of somatotropic complex is STH- Somatomedin hormones, sexual hormones and thyroniel hormones on the primary cartilage (epiphyseal cartilages of long bones, cartilages of the nasal septum and sphenoid etc) has the “Cybernetic” form of common.
Enlowâ€™s counterpart principle The growth of any given facial or cranial part relates specifically to another structural and geometric counterparts of the face and cranium. This counterpart principle explains the balanced growth between different regions of the cranium even thought they have different growth rates .
Different cranial base parts and their counterparts. Anterior base and naso- maxillary complex. Middle cranial fossa and horizontal pharyngeal space dimensions. Middle cranial fossa and breadth of the ramus. www.indiandentalacademy.com
Anomalies of development www.indiandentalacademy.com
The calvaria is particularly susceptible to a number of congenital defects ranging from chromosomal to hormonal in their etiology. The time of closure of the sutures is altered in many of these afflictions, leading to variable distortion of skull shape In conditions such as cretinism, progeria, trisomy21 and cleidocranial dysostosis there is delayed midline ossification of frontal and saggital sutures of the calvaria, so that anterior fontenelle may remain open into adult life. The resulting brachycephalic skull results in a bossed forehead of highly curved frontal and parietal bones and hypertalorism, partly obscuring the smaller brain case. Another abnormality is premature fusion of sutures (craniosynostosis) Encephaloceles are defects in closure of the foramen caecum at the ethmoid frontal suture allowing hernation of the cranial contents into the face www.indiandentalacademy.com
In anencephaly absence of the calvaria results in craniosehisis, characterized by short narrow chondrocranium. Afflication of cartilage growth produce a reduced cranial base, with increased angulation due to loss of flattening effect of growth of spheno occipital synchondroses. This results in dished deformity of middle 1/3rd of facial skeleton accentuated by a bulging of neurocranium. Achondroplasia, cretinism and Downâ€™s syndrome all produce a similar characteristic facial deformity by their inhibiting effect on chondrocranial growth. Certain forms of dental malocclusion may be related to defects of the chondrocranium that minimize the space available for the maxillary dentition. www.indiandentalacademy.com
VARIOUS SYNDROMES AND DEFECTIVEDEVELOPMENTAL CONDITIONS SYNDROME 13 TRISOMY– EXTRA CHROMOSOME 13 IS PRESENT. CHARACTERIZED BY CLEFT LIP AND PALATE, MICROPTHALMIA (SMALL EYES), MICROCEPHALY WITH SEVERE BRAIN MALFORMATION, CONGENITAL HEART DEFECTS, POLYDACTILY (EXTRA DIGITS) AND A HOST OF OTHER ANOMALIES.
Trisomy 18 syndrome (Edwards syndrome) Most cases of this trisomy result into spontaneous abortion It occurs 1 in 6500 population Early death is the characteristic feature Retarded growth and development Prominent large forehead (occiput ) Small chin Heart defects are commonly seen www.indiandentalacademy.com
APERT SYNDROME: IS A SINGLE GENE DISORDER, CHARACTERIZED BY PREMATURE FUSION OF CRANIAL SUTURES, BIZARRE CRANIOFACIAL APPEARANCE, HIGHLY ARCHED PALATE, SYNDACTYLY (FUSION OF DIGITS) AND VARIOUS OTHER ABNORMALITIES OCCASIONALLY INCLUDING CONGENITAL HEART DEFECTS. THE PATIENT HAS BIZARRE PHYSICAL APPEARANCE AND MENTAL RETARDATION UNLIKELY TO MARRY AND HAVE CHILDREN. www.indiandentalacademy.com
Craniosynstosis â€“ It is a condition resulting from premature fusion of the cranial sutures like Apert syndrome. In this, head shape depends on which sutures are prematurely synostosed, the order in which they synostose and timing at which they synostose. This condition may be prenatal or perinatal in onset or may occur later during infancy or childhood. The earlier the synostoses occur, the more dramatic is the affect on subsequent cranial growth and development. The later synostosis occurs, the less is the effect on the cranial growth and development. www.indiandentalacademy.com
The various shapes of the calvaria when various sutures are prematurely fused are Normocephaly â€“ is the normal head shape Dolicocephaly â€“ if the saggital suture is prematurely synostosed, the calvaria is restricted in its lateral growth and compensates by permitting more passive growth to occur at the coronal and lambdoidal sutures. Brachycephaly â€“ if the cornonal suture is prematurely synostosed, growth is arrested in an antero posterior direction, compensatory growth occurring laterally at the patient saggital suture. www.indiandentalacademy.com
Plagiocephaly â€“ is an asymmetric skull shape. This may be produced by unilateral closure of the coronal suture or unilateral closure of the lamboidal suture. Trigonocephaly â€“ if the metopic suture closes prematurely a triangular calvaria results known as Trigonocepyhaly. www.indiandentalacademy.com
Achondroplasia Characterized by unusual crainio facial configuration and disproportional short stature. Chromosomal disorder (autosomal dominant) Enlarged calvaria, frontal bossing, large frontal sinus, occipital prominence, normal anterior cranial base length, shortened posterior cranial base length, shortened posterior cranial base length, short upper facial height, short nasal bone, short upper facial height, short maxilla, posterior tilt of nasal floor. www.indiandentalacademy.com
Prognathic mandible that is anteriorly placed but of normal size, normal gonial angle and high coronoid process. In achondroplasia bone preformed in cartilage is affected Membrane bones are not affected. The condition is due to abnormal endochondral bone formation on the development of skull as a whole. The mandible is normal in length because growth a condylar cartilage is appositional. In achondroplasia only interstitially growing cartilagewww.indiandentalacademy.com is affected.
Marfanâ€™s syndrome Hereditary disease. Basically defect of connective tissue related to defective organization of collagen. Shape of face is long and narrow. High arched palate. Also seen are excessive length of tubular bones and arachnodactaly or spidery fingers.
Downâ€™s syndrome Flat face . Large anterior fontanelle, open suture, small slanting eyes with epicanthal folds, open mouth, frequent prognathism Sexual underdevelopment, cardiac abnormality and hypermobility of jaws.
Hyperthyroidism Under functioning of thyroid gland due to failure of pituitary gland or atrophy or destruction of the thyroid gland. Decreased ability of the thyroid gland to produce sufficient hormone. Here base of the skull is shortened leading to retraction of the bridge of the nose with flaring. The face is wide failing to develop in the longitudinal direction . The mandible is underdeveloped and the maxilla is overdeveloped . Mental retardation. www.indiandentalacademy.com
Cleidocranial dysplasia: It is a disease of unknown etiology, often hereditary. Characterized by abnormalities of the skull, teeth, jaws and shoulder girdle and stunting of long bones. In the skull the fontanells remain open or at least show delayed closure The sagittal suture is characteristically sunken giving the skull a flat appearance. Shoulder meets in midline.
Clinical Importance www.indiandentalacademy.com
Craniofacial skeletal growth is very important in orthodontics since craniofacial morphology are the source of serious malocclusions. The configuration of the basicranium determines a personâ€™s head form type, which in turn sets up many proportionate features characterizing facial type. If the basicranium is long and narrow, this result in dolicochphalic facial type, which will result anterioposteriorly and vertically, elongated facial profile and this will result in mandibular retrusion. If the basicranium is round, this will result in brachycephalic facial type, this will result in anterioposteriorly and vertically shorter facial profile. This will result in either mandibular protrusion or bimaxillary protrusion. www.indiandentalacademy.com
The growth of the cranium also has direct effect on the placement of maxilla and mandible. The mandible is attached to mid cranial fossa through the condyles. Thus ramus place the mandibular arch in occlusion with the maxillary arch following a pattern set up by the basicranium. Similarly, the nasomaxillary complex is suspended from the anterior cranial fossa. So the configuration of the palate and maxillary arch is thus established by the basicranium www.indiandentalacademy.com
CONCLUSION A thorough background in craniofacial growth is necessary for every orthodontist.
Even for those who never work with
children, it is difficult to comprehend conditions observed in adults without understanding the development processes that produced these problems. Craniofacial skeletal growth is very important in orthodontics, since variations in craniofacial morphology are the source of most serious malocclusions and clinical damages.
Thank you For more details please visit www.indiandentalacademy.co m