Cranial vault

cranial vault

1. GOOD MORNING

2. CONTENTS INTRODUCTION PRE-NATAL GROWTH AND DEVELOPMENT AT BIRTH POST- NATAL GROWTH AND DEVELOPMENT CLINICAL IMPLICATIONS CONCLUSION REFERENCES

3. INTRODUCTION Skull At Birth – 45 Bony Elements In Adult – 22 bones Face – 14 bones Cranium - 8 bones

4. INTRODUCTION CRANIOFACIAL COMPLEX : COMPRISES OF 4 REGIONS CRANIAL VAULT CRANIAL BASE NASO-MAXILLARY COMPLEX MANDIBLE

5. CRANIAL VAULT The  cranial vault  is the space in the skull within the  neurocranium , occupied by the brain. NEUROCRANIUM is also known as brain case.

6. Neurocranium is the fastest growing region in craniofacial complex at birth. NEUROCRANIUM VAULT OF SKULL OR CALAVARIA OR DESOMOCRANIUM CRANIAL BASE OR CHONDROCRANIUM FROMED BY INTRAMEMBRANOUS BONE FORMATION FROMED BY ENDOCHONDRAL OSSIFICATION

7. OVERVIEW SITE OR LOCATION TYPE OF GROWTH OCCURING AT THAT LOCATION MECHANISM OF GROWTH CONTROLLING FACTORS IN THAT GROWTH

8. GROWTH : “Any change in morphology which is within measurable parameter”- MOSS DEVELOPMENT : “Considered as a continuum of causally related events from fertilization of ovum onwards” –MOSS .

9. CORRELATION BETWEEN GROWTH AND DEVELOPMENT Growth is basically anatomic phenomenon and quantitative in nature Development is basically physiologic phenomenon and qualitative in nature.

10. DEVELOPMENT = GROWTH + DIFFERENTIATION + TRANSLOCATION

11. SITE OR LOCATION In cranial vault or desmocranium growth is accomplished by proliferation of connective tissue between the sutures and its replacement by bone. Despite by rapid ossification of the cranial vault in the terminal stages of fetal life, bones of vault is separated by fontanelles when child is born

12. TYPE OF GROWTH OCCURRING AT THAT SITE : Intramembranous bone formation or Direct ossification or Membranous bone formation. Process of bone formation is by undifferentiated mesenchymal cells.

13. MECHANISM OF GROWTH MESENCHYMAL CELLS undergo condensation at site of bone formation Some lay bundle of the first fibrous bony matrix Differentiate into osteoblasts Fibrous bony matrix gets mineralized and blood vessels are retained in close proximity to bony trabeculae

14. Some of these cells get enclosed by their own deposits called osteoid matrix Deposition of calcium salts into osteoid matrix lead formation of lamella Osteoblast move away from lamella Osteoblast entrapped between lamella are called osteocytes

15. Therefore bone formation comprises of two entities : OSTEOCYTES INTRA CELLULAR MEMBRANE

16. Resorption and deposition can be observed continuously , during growth period deposition overstrips resorption. Balanced in the adult and reversed in old age… Sutures : bones grows towards each other and in the cranium, the osteogenic region between them is composed of connective tissue. This zone is called suture.

17. ENDOCHONDRAL OSSIFICATION Precursor Cartilage  Largely responsible for elongation of individual bones, thus constitutes mainly for increase in Height or Growth.

18. Prenatal growth is characterized by a rapid increase in cell numbers and fast growth rates Post natal growth is the first 20 years of growth after birth Postnatal growth is characterized by declining growth rates and increasing maturation of tissues

19. PRENATAL DEVELOPMENT

20. GERM LAYERS Ectodermal cells will give rise to the nervous system; the epidermis and its appendages (hair, nails, sebaceous and sweat glands); the epithelium lining the oral cavity, nasal cavities and sinuses; a part of the intraoral glands, and the enamel of the teeth  Endodermal cells will form the epithelial lining of the gastrointestinal tract and all associated organs. The mesoderm will give rise to the muscles and all the structures derived from the connective tissue(e.g., bone, cartilage, blood, dentin, pulp, cementum and the periodontal ligament )

21. PRE-NATAL GROWTH OF CRANIAL VAULT Normally, cranial vault is derivative of mesenchyme , which is initially in the form of capsular membrane around developing brain Capsular membrane consist of two parts.

22. Outer membrane VAULT BASE

23. In somite period embryo, the neural tube’s covering duramater and its surface ectoderm are in contact . The transient maintenance of this contact during development causes a Dural projection and extends into future frontonasal area Ossification of calvarial bones depends on presence of brain

24. ECTOMENINX MESODERMAL ORIGIN NEURAL CREST ORIGIN PARIETAL SPHENOIDAL PETROUS TEMPORAL OCCIPITAL FRONTAL LACRIMAL SQUAMOUS TEMPORAL MAXILLA MANDIBLE NASAL ZYGOMATIC

25. OSTEOLOGY : Cranial vault consist :

26. Frontal bone : The pair of frontal bone appears from single primary ossification centers at 8 th week of post conception Fusion between these centers occur 6-7 th months of post conception

27. At birth, frontal bone is separated by frontal suture or metopic suture. Fusion of these suture occurs 2 nd -7 th year into single bone.

28. PARIETAL BONE Pair of parietal bone forms roof of vault Two primary ossification centers for each bone appear at the parietal eminence in the 8 th week of post conception Fuse in 4 th month of post conception D elayed ossification results in sagittal fontanelle at birth

29. OCCIPITAL BONE The supranuchal squamous portion of the occipital bone ossifies intramembranously in 8 th week post conception, rest by endochondrally

30. TEMPORAL BONE The squamous portion ossifies intramembanously at single center, the tympanic ring ossifies from four centers in the 3 rd month of conception. The rest of the bone endochondrally .

31. SPHENOID BONE

32. The sphenoid bone is unpaired. It forms the middle part of the base of skull and extend into lateral wall of vault. Ossification is mainly by endochondral ossification .

33. If any unusual ossification centers develop between bones, their independent existence is recognizable as small sutural or wormian bones

34. AT BIRTH At birth, bones of face and jaws are under developed. At birth cranium : face= 8:1 later, reduces to 2:1 The individual calvarial bones are separated by sutures of variable width and by fontanelles Fontanelles : one of the membrane-covered spaces remaining at the junction of the sutures in the incompletely ossified skull of the fetus or infant.  Actually there are two soft spots close together, representing gaps in the bone structure which will be filled in by bone during the normal process of growth

35. The anterior  fontanelle  is diamond shaped and lies at the junction of the frontal and parietal bones. This  fontanelle  usually fills in and closes between the 18 th -24 th month of life

36. The posterior fontanelle lies at the junction of the occipital and parietal bone, is triangular in shape, and usually closes by the 2months after birth. The anterolateral fontanelles closes 3 months after birth. The posterolaterl closes by 2 nd year. The flexible membranous junctions between the calavarial bones allow the narrowing of the sutures and fontanelles and the over riding of these bones when they become compressed in traversing the pelvic birth canal

37. SUTURES Coronal suture : Between frontal and 2 parietal bone

38. Sagittal suture: between 2 parietal bone. Lamdoidal suture: between parietal and occipital bone Squamous suture : between parietal and temporal bone Parietomastoid suture: between parietal and temporal bone Sphenofrontal suture : between sphenoid and frontal bone

39. S phenoparietal suture : between sphenoid and parietal bones. Sphenosqamosal suture : between sphenoid and temporal bones. Sphenozygomatic suture : between sphenoid and zygomatic bones. Zygomaticotemporal suture : between zygomatic and temporal bones. Zygomaticofrontal suture : between zygomatic and frontal bones.

40. VIEWS OF SKULL NORMA VERTICALIS

41. NORMA OCCIPITALIS

42. NORMA FRONTALIS

43. NORMA LATERALIS

44. There must be a beginning of any great matter, but the continuing unto the end until it be thoroughly finished yields the true glory . SIR FRANCIS DRAKE {1587}

45. PTERION

46. FACTORS AFFECTING PRE-NATAL GROWTH INTRINSIC GENETIC FACTORS EPIGENTIC FACTORS ENVIRONMENTAL FACTORS

47. CRANIAL DIFFERENTIATION

48. RELATED TO THE GROWTH OF BRAIN 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 .

49. The cranial vault increases in width by “fill in” ossification of proliferating connective tissues in the coronal, lambdoidal , interparietal , parieto - shpenoidal sutures. The mid sagittal sutures between the parietal bones does not close. 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 osseous structures  

50. CEPHALOCAUDAL GRADIENT OF GROWTH 

51. POST-NATAL GROWTH THE CALVARIA The endocranial surface of the calvaria is predominantly depository The lining bony surface of the cranial floor is mainly resorptive . Circumcranial reversal line

52. Circumcranial Reversal Line

53. Growth of the cranial vault – direct influence of Neurocranial capsule 

54. NEUROCRANIAL CAPSULE: This capsule expands in response to a volumetric increase of the capsular neural matrix. The embedded bones are passively carried outward, by process of translative growth

55. As brain expands separate bones of calvaria displaced outwardly. Passive movement. Each separate bone is enmeshed within connective tissue stroma.  P rimary displacement- tension in sutural membranes. Response-new bone deposition-sutural edges. Each separate bone enlarges-circumference. Endosteal surfaces- resorptive , overall thickness &expands medullary spaces. 

56. Thickening not uniform : Inner table Brain. Outer table Mechanical influences and functional stresses. Growth of the frontal sinus.

57. Basically it is the combination of   SUTURAL GROWTH Sutures are articulation within craniofacial complex . Location are genetically determined but environmentally influenced. Firm bond with adjacent bone they allow slight movement & absorb stresses.

58. According to Pritchard 1956 Suture is composed of 5 layers: - Pair of cambian (osteogenic ), Pair of Capsular Layer, Middle loose connective tissue layer.

59. In course of maturation cambian layer is reduced to single layer of osteoblast & capsular layer become thicker . Vascularity of middle loose layer is increased

60. TYPES Serrate Sutures: - Saw like/ notched e.g. Sagittal, coronal ,can withstand force, blow . Denticulate Sutures: - Small tooth like e.g. Lambdoid suture. Squamous/ Beveled: - Bone overlaps the other bone. e.g. temporal & parietal sutures. Plane / battened: - Flat end rough & irregular e.g. midpalatal suture.

61. All motion of cranial bones are interdependent. No cranial bones move independently. Restrictions in any one part of the cranium will affect the rest of the cranial mechanism . The sphenobasilar junction, also known as the sphenobasilar synchondrosis (or symphysis a.k.a. SBS) is the reference point around which cranial motion patterns are described

62. APPOSITION & RESORPTION : Accretion to the calvarial bones is predominantly sutural until 4th yr . Remodeling of curved bony plates allow for their flattening out to accommodate the increase surface area. Achieved by combination of endocranial erosion & ectocranial deposition. Angulation between bones changes. In addition to rotation, the separate bones also rotate within themselves .

63. CEPHALIC INDEX Is the ratio of the maximum width of the head to its maximum length multiplied by 100 female male type < 75 < 75.9 dolichocephalic 'long-headed' 75 to 83 76 to 81 mesaticephalic 'medium-headed' > 83 > 81.1 brachycephalic 'short-headed'

64. CENTRIFUGAL FORCE Precocious development of brain determines early predominance of neurocranium . Brain & vault develop very rapidly, very early but also growth ceases early than face.

65. NEUROCRANIUM: FACE 8:1 Birth 6:1 2 nd year 4:1 5 th year 2:1 Adult

66. GENERAL FACTORS INFLUENCING CRANIAL VAULT MORPHOLOGY   RACE Vault form is most typical racial expression, Dolichocephalic = Northern & Southern European, Brachycephalic = Middle Europeans, Asian people .

67.   HEREDITY: - Vault shows interfamilial correlation than breadth & length. NUTRITION: - Malnutrition leads to shortened neurocranial length, width, height (in Rats) “ROBUSTICITY INDEX” ( wt per unit length) of cranial vault decrease upon protein- calorie malnutrition. 

68. VARIOUS THEORIES OF GROWTH, AND HOW THEY RELATE TO THE CRANIAL VAULT Genetic Theory Sicher’s Sutural Theory Scott’s Cartilaginous Theory Moss’s Functional Matrix Theory

69. GENETIC THEORY : - Growth was genetically determine. Earliest t heory to put forward   .

70. SICHER’S SUTURAL THEORY: - Believes craniofacial growth occurs at the sutures. Local factors, like muscle activity had only a mild effect . 

71. SCOTT’S CARTILAGINOUS THEORY:- Inherent growth potential of Cartilages. Sutures respond secondarily.

72. MOSS’ FUNCTIONAL MATRIX THEORY: - P ostulated the role of functional matrices which are formed by non osseous tissue. EEEEEA EXPANDING BRAIN VAULT BASE

73. VAN LIMBORGH'S SUMMARIZATION:- Chondrocranial growth is controlled mainly by Intrinsic genetic factors. Desmocranial growth is controlled by few Intrinsic genetic factors. Cartilaginous parts of the skull must be considered as growth centre . Sutural growth is controlled mainly by influences originating from the skull cartilage & adjacent skull structure. 

74.   Periosteal growth largely depends upon growth of adjacent structures .  Sutural & periosteal growth are additionally governed by local non genetic environmental influence.

75. CLINICAL IMPLICATION   DEFECTS IN CLOSURE OF FORAMEN CAECUM: - Dura remains in contact with the ectoderm in the region of the anterior neuropore . Ventral bending of the fronto -nasal process brings this junction close to the future nose . Nasal capsule forms around this, and the junction sinks forming the foramen caecum. The dura then separates from the ectoderm, and foramen caecum closes. If this foramen fails to close, dura can herniate in to the nose. Also formation of dermoid cysts, sinus or encephalocele .

76.  Altered time closure of sutures-variable distortions of skull shape. Delayed midline ossification of frontal & sagittal sutures –anterior fontanelle may remain open. Cretinism, progeria, trisomy 21,cleidocranial dysostosis . Premature synostosis – Apert’s syndrome & Crouzon syndrome.

77. CRANIOSYNOSTOSIS Premature fusion of sutures results in the premature cessation of sutural growth. Abnormal intrauterine compression of the cranium is a factor in causing premature fusion because it alters the immature sutural tissue and initiates mineralization of the sutural ligament It is largely confined to the calvaria .

78. Johnny B. D ,  M.D.,  John A.  Persing , M.D.,  William C. Broaddus, M.D., Ph.D., and  John A.Jane , M.D., Ph.D . Cranial vault growth in craniosynostosis Journal of Neurosurgery February 1989 / Vol. 70 / No. 2 / Pages 159-165 The deformities resulting from premature closure of a coronal, sagittal, metopic, or lambdoid suture can be predicted on the basis of the following observations: cranial vault bones that are prematurely fused secondary to single suture closure act as a single bone plate with decreased growth potential ; asymmetrical bone deposition occurs mainly at perimeter sutures, with increased bone deposition directed away from the bone plate;

79. 3 ) enhanced symmetrical bone deposition occurs along both sides of a non-perimeter suture that is a continuation of the prematurely closed suture 4) sutures adjacent to the prematurely fused suture compensate in growth more than those sutures not contiguous with the closed suture .

80. Premature sagittal suture closure restricts growth in a perpendicular plane, thus the head will not grow sideways and remain narrow. This is best seen in a view standing above the child looking downward at the top of the head. Compensatory growth  occurs forward at the coronal suture and backward at the lambdoid suture giving respectively a prominent forehead, called frontal bossing, and a prominent back portion of the head, called coning. SCAPHOCEPHALY

81. TRIGONOCEPHALY Trigonocephaly  is a result from the premature closure of the metopic suture. Using Virchow's law again to predict the resulting deformity, this fusion will result in a narrow forehead, which is even further emphasized by ridging of the suture.  Compensatory growth occurs at both the coronal sutures, thereby pushing the forehead forwards .

82. The resulting shape can best be assessed from a top view again, which will reveal a somewhat triangular form of the head. Trigonocephaly is also a Greek derived word, which can be translated as triangular shaped head. A facial feature of metopic synostosis is  hypotelorism ; in the frontal view, it can be seen that the width between the eyes is smaller than usual.

83. PLAGIOCEPHALY Anterior plagiocephaly Posterior plagiocephaly Anterior plagiocephaly is a clinical description of unilateral coronal synostosis .   Children born with unilateral coronal synostosis develop due to compensatory mechanisms a skew head; a plagiocephaly

84. Unilateral  lambdoid  synostosis is also called posterior plagiocephaly , indicating that this gives, just like unilateral  coronal  synostosis, a 'skew head'. The difference is that this time, the deformity mostly shows at the  occiput .

85. BRACHYCEPHALY BRACHYCEPHALY or a 'short head', is the result of a closure of both the coronal sutures. Following Virchow's law, this will result in a child's head with a restriction of growth in the forward direction and in the backward direction: recessed frontal bones and a flattened occiput. Compensatory growth will occur sideways, due to the sagittal suture, and upwards, due to the lambdoid sutures

86. OXYCEPHALY Oxycephaly, also known as  turricephaly  and  high-head syndrome, is a type of cephalic  disorder. This is a  term  sometimes used to describe the premature closure of the coronal suture plus any other suture, like the lambdoid suture.

87. PANSYNOSTOSIS Pansynostosis can present in several ways. The appearance can be the same as that seen with primary  microcephaly : a markedly small head, but with normal proportions. However , pansynostosis can also appear as a  Kleeblattschädel  (cloverleaf skull), which presents with bulging of the different bones of the  cranial vault . The condition is associated with thanatophoric   dwarfism

88. Apert syndrome : an abnormal skull shape, small upper jaw, and fusion of the fingers and toes. Crouzon syndrome : A craniofacial birth abnormalities with bilateral coronal suture fusion. Anterior and posterior of skull shortness, flat cheek bones and a flat nose are their features. Pfeiffer syndrome : abnormalities of the skull, hands, and feet wide-set, bulging eyes, an underdeveloped upper jaw, beaked nose .

89. Pierre Robin syndrome  : abnormalities in the  facial skeleton , resulting in a smaller than normal lower jaw or receding chin. The tongue often falls back in the  pharynges  causing difficulty breathing. Saethre – Chotzen syndrome : short or broad head. the eyes may be spaced wide apart and have palpebral ptosis (droopy eyelids), and fingers may be abnormally short and webbed.

90. Pfeiffer syndrome Apert syndrome

91. Saethre– Chotzen syndrome

92. Pierre Robin syndrome

93. MICROCEPHALY Microcephaly  is a medical condition in which the brain  does not develop properly resulting in a smaller than normal head. Microcephaly may be present at birth  or it may develop in the first few years of life. Sutures and fontanelles close prematurely.

94. Infants  with microcephaly are born with either a normal or reduced head size. Subsequently, the head fails to grow, while the face continues to develop at a normal rate, producing a child with a small head and a receding forehead, and a loose, often wrinkled scalp. As the child grows older, the smallness of the skull  becomes more obvious, although the entire body also is often underweight and dwarfed. Development of motor functions and speech  may be delayed

95. HYDROCEPHALUS Hydrocephalus  is a condition in which there is an accumulation of cerebrospinal fluid  (CSF) within the brain .  This typically causes increased pressure inside the skull Fusion of sutures is delayed.

96. Symptoms of increased intracranial pressure may include headache, vomiting, nausea, papilledema, sleepiness   or coma. Elevated intracranial pressure  may result in tonsillar herniation, with resulting life-threatening brain stem  compression.

97. Hydrocephalus can be successfully treated by placing a drainage tube (shunt) between the brain ventricles and abdominal cavity. There is some risk of infection  being introduced into the brain through these shunts, however, and the shunts must be replaced as the person grows. A subarachnoid hemorrhage may block the return of CSF to the circulation. TREATMENT

98. Anencephaly  is the absence of a major portion of the  brain ,  skull , and  scalp  that occurs during  embryonic development . ANENCEPHALY

99. CONCLUSION The evaluation of the growth and development of the individual patient is an important part of orthodontics as a basis of comparison with the normal as a means of discovering and diagnosing malocclusion, and as the foundation for planning orthodontic treatment.

100. Thank you !

101. FUCTIONAL MATRIX HYPOTHESIS : Claims that the origin, growth and maintenance of all skeletal tissues and organs are always secondary compensatory and obligatory responses to temporally and operationally prior events or process that occur in specifically related non skeletal tissue organs or functioning spaces.