Development of face

embryology, development of face, anomalies, dental, public health significance

1. DEVELOPMENT OF FACE 1

2. INTRODUCTION PHASES OF DEVELOPMENT PHARYNGEAL ARCHES FACE MANDIBLE MAXILLA PALATE NASAL CAVITIES SINUSES LIPS TONGUE SALIVARY GLAND TEETH ANOMALIES OF FACE PUBLIC HEALTH SIGNIFICANCE CONCLUSION REFERENCES CONTENTS 2

3. Every individual spends the first nine months of its life within the womb or uterus of its mother. INTRODUCTION 3

4. During this period, it develops from a small one- celled structure to an organism having billions of cells. The most spectacular changes occur in the first 2 months of IUL. During these 2 months ,we call the developing individual an embryo. 4

5. PHASES OF DEVELOPMENT 5

6. 6 CLEAVAGE & BLASTOCYST FORMATION The intercellular spaces become confluent, and finally, a single cavity, the blastocele, forms. At this time this embryo is a blastocyst.

7. IMPLANTATION 7

8. 8 TIME PERIOD DEVELOPMENTAL STAGES 2 ND WEEK Formation of amniotic cavity Extra embryonic mesoderm Chorionic plate formation

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11. Rod-like thickenings of mesoderm in the foregut. At first 6 arches. 5 th arch disappear, only 5 remains. PHARYNGEAL ARCHES 11

12. The ventral ends of the arches of the right and left sides meet at the middle line in the floor of the pharynx. 12

13. 13 The y brin g ab o u t el o n g a ti o n of the r e g i o n b e t w e e n t he stomatodeum and the pericardium forming neck.

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15. 15 ARCH NERVE SUPPLY ARTERIAL SUPPLY MUSCLES OF ARCH First Mandibular Maxillary artery External carotid artery Medial and lateral pterygoids Masseter Temporalis Mylohyoid Anterior belly of digastric Tensor tympani Tensor palati Second Facial Facial artery Stapedial artery Facial muscles Occipitofrontalis Platysma Stylohyoid Posterior belly of digastric Stapedius Auricular muscles

16. ARCH NERVE SUPPLY ARTERIAL SUPPLY MUSCLES OR ARCH Third Glossopharyngeal Internal carotid artery Common carotid artery Stylopharyngeus Fourth Superior laryngeal Subclavian artery Sixth Recurrent laryngeal Pulmonary artery 16 Muscles of larynx and pharynx

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18. Mesenchymal gene expression is initially determined by homodomain-containing transcription factors 18 DERIVATIVES OF SKELETAL ELEMENTS

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20. ENDODERMAL POUCHES ORGANS FORMED First Tongue Auditory tube Tubotympanic recess Middle ear with tympanic antrum Second Tonsil Tubotympanic recess Third Inferior parathyroid gland Thymus Fourth Superior parathyroid gland Thyroid gland Fifth or ultimobranchial pouch Caudal pharyngeal complex 20

21. The facial components are derived from five facial prominences The 5 prominences which appear around the stomodeum are 1.Single frontonasal prominence 2.Paired maxillary prominence 3.Paired mandibular prominence DEVELOPMENT OF FACE 21

22. By 4 th week  center of growing face  stomodeum After formation of head fold, the developing brain and pericardium forms two prominent bulgings . 22

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27. DEVELOPMENT OF LIPS 27

28. DEVELOPMENT OF CHEEKS After formation of upper & lower lip, the Stomatodeum is very broad. It is bounded above by Maxillary Process & below by Mandibular Process. These processes undergo progressive fusion with each other to form Cheeks 28

29. Bilateral oval thickening of the surface ectoderm- nasal placodes have developed in the inferolateral parts of the frontonasal prominence convex but later, a flat depression in each placode. DEVELOPMENT OF NASAL CAVITIES 29

30. The mesenchyme in the margins of the placode proliferates, and forming horse-shoe shaped elevations-the medial and lateral nasal prominences. As a result, the nasal placodes lie in depressions, called nasal pits . 30

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32. 32 Nasolacrimal duct develops from a rod like thickening of ectoderm of nasolacrimal groove. thickensone end of this duct expands and forms lacrimal sac .drains into inferior meatus in lateral wall of nose.

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34. Paranasal sinuses appear as diverticula from nasal cavity. The diverticula gradually invades the bones. Enlargment of paranasal sinuses is associated with the overall enlargement of the facial skeleton including the jaws. This provide space in the jaws for growth and eruption of teeth. DEVELOPMENT OF PARANASAL SINUSES 34

35. Forms around 3rd month of intra-uterine life. Develops by expansion of nasal mucous membrane into maxillary bone. Later enlarges by resorption of internal wall of maxilla. DEVELOPMENT OF MAXILLARY SINUS 35

36. The maxilla develops from a center of ossification in the mesenchyme of the maxillary process of the first arch. Center of ossification is closely associated with the cartilage of the nasal capsule. Bone formation spreads : – From center Posteriorly below orbit towards forming zygoma – Anteriorly future incisor region – Superiorly frontal process DEVELOPMENT OF MAXILLA 36

37. DEVELOPMENT OF PALATE 37 PRIMARY PALATE SECONDARY PALATE The primary palate represents only a small part lying anterior to the incisive fossa , of the adult hard palate. The Secondary Palate is the primordial of hard and soft palate posterior to the incisive fossa

38. The mesoderm in the palate undergoes intramembranous ossification to form the hard palate. Ossification does not extend into the posterior portion called as soft palate. 38

39. The part of the palate derived from frontonasal process forms the premaxilla; which carries the incisor teeth. After the development of secondary palate distinction between the oral and nasal cavity is possible. Development 7-8 weeks and completes around the 3rd month of gestation. 39

40. 3 outgrowths appear one nasal septum and two palatine shelves. They converge and fuse in the midline. Displacement of tongue from between the palatine shelves by the growth pattern of the head is a contributing factor closure of palate 40

41. Meckels cartilage forms the lower jaw in primitive vertebrates. In humans, Meckel’s cartilage has a close positional relationship to the developing mandible but makes no contribution to it. At 6 weeks of development this cartilage extends as a solid hyaline cartilaginous rod, surrounded by a fibrocellular capsule, from the developing ear to the midline of the fused mandibular processes. DEVELOPMENT OF MANDIBLE 41

42. The two cartilages of each side are separated in the midline by a thin line of mesenchyme During 6th week; a condensation of mesenchyme occurs in the angle formed by the division of inferior alveolar nerve At 7th weeks; intramembranous ossification begins in this codensation forming the first bone of the mandible. 42

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44. Rapid spread of ossification posteriorly into the mesenchyme of the 1st arch. Spread of mandibular ossification away from meckels cartilage at the lingula. 44 DEVELOPMENT OF RAMUS

45. Skull can be divided into 3 components: The cranial vault The cranial base The face DEVELOPMENT OF THE SKULL 45

46. 46 The human skull consists of three components: (1) the membranous neurocranium , which constitutes the flat bones of the skull, (2) the cartilaginous neurocranium or chondrocranium which forms the majority of the skull base, and (3) the viscerocranium or facial skeleton.

47. 47 DEVELOPMENT OF BRAIN The brain begins as three primary vesicles : 1.prosencephalon – forebrain 2.mesencephalon – midbrain 3.rhombencephalon – hindbrain Later the brain divides into five secondary vesicles.

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49. Region of eye is 1st seen as ectodermal thickenings, lens placode, which appears lateral & cranial to the nasal placode. Sinks below the surface & cut off from surface ectoderm. DEVELOPMENT OF EYE 49

50. Developing eyeball produces a bulging. Bulgings are at first seen laterally & lie in the angles between the maxillary& lateral nasal processes. After narrowing of the frontonasal process they lie forward. 50

51. 6 auricular hillocks-forms primordia of the auricle around the 1 st pharyngeal groove(3 on each side) and primordium of external acoustic meatus. Initially the external ears are in the neck region later they ascend to the side of the head DEVELOPMENT OF EXTRERNAL EAR 51

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53. Primary epithelial band is a band of epithelium that has invaded underlying ectomesenchyme along each of the horseshoe shaped future dental arches. At 7th week the PE band divides into Dental lamina and vestibular lamina. The dental lamina shows a series of local thickenings- enamel organ. DEVELOPMENT OF TEETH 53

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55. The dental lamina is established in the sixth week of intrauterine life. The dental lamina serves as primordium of the ectodermal position of the deciduous teeth. Permanent molars arise directly from a distal extension of the dental lamina. 55

56. Genes expressed during tooth development Lef – lymphoid enhancer- binding factor (TF) Pax – paired box homeotic gene Fgf – fibroblast growth factor Bmp – bone morphogenetic proteins Barx – BarH1 homologue 56

57. Develops at about 4 weeks. Local proliferation gives rise to a number of swellings in the floor of the mouth. 2 lateral lingual swellings enlarge and merge with each other and the tuberculam impair to form a large mass, from which anterior 2/3rd of the tongue is formed. DEVELOPMENT OF TONGUE 57

58. Root of the tongue arises from a large midline swelling developed from the mesenchyme of the 2nd 3rd & 4th arches. Swelling consists of copula and large hypobranchial eminence. As tongue develops, hypobranchial eminence overgrows the copula. Posterior part of the fourth arch marks the development of the epiglottis. 58

59. The salivary glands develop as outgrowths of the buccal epithelium. The outgrowths are at first solid and are later canalized. They branch repeatedly to form the duct system. The terminal part of the duct system develop into secretory acini. DEVELOPMENT OF SALIVARY GLAND 59

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61. DEVELOPMENTAL ANOMALIES 61

62. 62 Congenital auricular sinuses PHARYNGEAL ARCH DEFECTS

63. Preauricular sinus is a congenital anomaly that occurs because of a malformation during the merging of first and second branchial clefts, which form the ear in the course of embryonic development. Although it is usually non-symptomatic, it can rarely be seen together with recurrent swelling and discharge, and inflammatory infections. 63 PHARYNGEAL ARCH DEFECTS

64. Most of the preauricular sinuses do not show symtptoms for a life time and do not need a treatment. Preauricular sinus infection develops in few patients, and after the symptoms are observed, the sinus tract is clearly marked out and the patient is advised for a surgical excision. Inadequate excisions often lead to recurrences 64 PHARYNGEAL ARCH DEFECTS

65. 65 Cervical vestiges

66. Internal branchial fistulas : It is very rare and in this the cervical sinus is connected to the lumen of the pharynx by a small canal which usually opens in the tonsillar region. 66 PHARYNGEAL ARCH DEFECTS

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68. FIRST &SECOND ARCH SYNDROME MICROTIA & ATRESIA 68

69. HEMI-FACIAL MICROSOMIA (HFM) : Hemifacial microsomia is known by a variety of other names, including craniofacial microsomia, first and second pharyngeal arch syndrome, Goldenhar syndrome, and lateral facial dysplasia. 69 PHARYNGEAL ARCH DEFECTS

70. It occurs when soft tissue and bone from the pharyngeal arches on one side of a child's face fail to develop fully 70 PHARYNGEAL ARCH DEFECTS

71. Either one-sided (unilateral) or two-sided (bilateral) underdevelopment of the eye, cheekbone, lower jaw, facial nerve and muscles. There may be hearing loss caused by the underdevelopment of the middle ear. The soft palate may move to the unaffected side because of muscle weakness on the affected side. 71 PHARYNGEAL ARCH DEFECTS

72. The tongue may be small with weakness on the affected side. The facial muscles is weak on the affected side or, rarely, on both sides. 72 PHARYNGEAL ARCH DEFECTS

73. FIRST ARCH SYNDROME- PIERRE ROBIN’S SYNDROME 73

74. 74 ANOMALIES OF NOSE ARHINIA Bilateral absence of nasal placodes BOSMA ARHINIA MICROPHTHALMIA SYNDROME(BAMS)

75. 75 MIDLINE NASAL SINUS PROBOSCIS LATERALIS ANOMALIES OF NOSE

76. 76 HALF NOSE Unilateral absence of nasal placode . DOUBLE NOSE ANOMALIES OF NOSE

77. 77 ANOMALIES OF EYE BILATERAL ANOPHTHALMIA CONGENITAL APHAKIA

78. 78 CYCLOPIA CONGENITAL CATARACTS ANOMALIES OF EYE

79. 79 BLUE SCLERA COLOBOMA ANOMALIES OF EYE

80. CLEFT LIP 80

81. CLEFT PALATE 81

82. CLEFT PALATE-INCOMPLETE 82

83. 83 FACIAL CLEFT

84. Macroglossia, microglossia, aglossia Bifid tongue Ankyloglossia Geographical tongue Persistence of tuberculum impar Thyroid tissue within the muscles Remnants of thyroglossal duct Fissured tongue ANOMALIES OF TONGUE 84

85. 85 AGLOSSIA MACROGLOSSIA MICROGLOSSIA ANOMALIES OF TONGUE

86. 86 FISSURED TONGUE TONGUE TIE ANOMALIES OF TONGUE

87. 87 BIFID TONGUE GEOGRAPHIC TONGUE MEDIAN RHOMBOID GLOSSITIS ANOMALIES OF TONGUE

88. One or more teeth are absent. Supernumerary teeth. Individual tooth abnormality. Gemination. Malocclusion. Precocious eruption. Delayed eruption Improper formation of enamel and dentin. ANOMALIES OF TEETH 88

89. 89 SUPERNUMERARY TEETH PARTIAL ANODONTIA

90. 90 GEMINATION FUSION

91. 91 AMELOGENESIS IMPERFECTA DENTINOGENESIS IMPERFECTA

92. 92 VARIOUS SYNDROMES ASSOCIATED WITH CRANIOFACIAL DEFECTS Van der woude syndrome Achondroplasia Apert Syndrome Stickler Syndrome Cleidocranial Dysplasia Ectodermal Dysplasia Fetal alcoholic syndrome Treacher Collins Syndrome Hemifacial Microsomia ( Goldenhar Syndrome) cretinism Down's syndrome Hunter's syndrome San Syndrome

93. 93 PUBLIC HEALTH SIGNIFICANCE Prevention targets particular risk factors to reduce or minimize the occurrence of congenital anomalies.

94. 94 Smile Train is a charity providing corrective surgery for children with cleft lips and palates since 1999.

95. The knowledge of development of face and other structures in human being is very important for health professionals. If they are aware of the normal developments, then only they can identify abnormal developments which needs intervention at the early stage of child birth, otherwise the child have to suffer throughout the life with the defects which leads to disabilities 95 CONCLUSION

96. REFERENCES: Inderbir Singh - human embryology- 9 th edition. New Delhi; Macmillan Publishers India 2013 Keith L. Moore, Persuad T.V.N., Mark G. Torchia Before we are born-Essentials of embryology and birth defects, 8 th edition. Philadelphia; Elseviers Saunders 2013 Langman’s Medical Embryology-11 th edition. Romanes G.J. Cunningham’s Manual of Practical Anatomy Volume 3 Head, Neck and Brain, 15 th edition. NewYork ; Oxford University Press 2006. 96

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