DEVELOPMENT OF TONGUE THYROID GLAND, FACE AND PALATE

1. DEVELOPMENT OF TONGUE THYROID GLAND, FACE AND PALATE By Dr Samina Anjum

2. PHARYNGEAL ARCHES

6. Taste Buds • Anterior 2/3 tongue - Cranial nerve VII • Circumvallate papillae - Cranial nerve IX • Posterior 1/3 tongue - Cranial nerve IX • Most posterior part & Epiglottis - Cranial nerve X

7. TONGUE TIE

8. Development of Thyroid • The thyroid gland is the first endocrine gland to develop in embryo. • It begins to form about 24 days after fertilization • It develops from a median endodermal thickening in the floor of a primordial pharynx • Thickening soon forms a small outpouching called thyroid primordium

9. Cont…. • As the embryo and tongue grow, the developing thyroid gland descends in the neck, passing ventral to the developing hyoid bone and laryngeal cartilages • For a short time the thyroid gland is connected to the tongue by a narrow tube, the thyroglossal duct, disappears later

10. Cont… • At first the thyroid primordium is hollow but it soon becomes solid and divides into right and left lobes. • The two lobes are connected by the isthmus of the thyroid gland. • Isthmus lies anterior to the developing second and third tracheal rings.

11. Cont… • By seventh week it has reached its final site in the neck • The proximal opening of the thyroglossal duct persists as a small pit in the tongue, the foramen cecum • A pyramidal lobe extends upward from the isthmus in about 50% of people • The pyramidal lobe and the associated smooth muscle represent a persistent part of the distal end of the thyroglossal duct

12. Thyroglossal Duct Cysts & Sinuses Following infection of a cyst, a perforation of the skin occurs forming a thyroglossal duct sinus

14. Lingual Thyroid

15. DEVELOPMENT OF FACE • STOMODIUM: Is the depression between five elevations. Opposed to the primitive pharynx by buccopharyngeal membrane, which will break down later, then stomodeum communicates with the foregut.

22. Craniofascial Defects • Treacher Collin’s syndrome • Robbin’s sequence • Digeorge anomaly • Goldenhar syndrome

23. First Arch Syndrome Two Major types; both result in extensive facial abnormalites • Treacher Collins Syndrome • Pierre Robin Syndrome

24. Treacher Collins Syndrome • Autosomal dominant trait/teratogens • Malar hypoplasia • Mandibular hypoplasia • Down slanting palpepebral fissures • Malformed external ears

25. Pierre Robin Syndrome • Genetic or envoirmental factors • Mandibular hypoplasia • Micrognathia • Cleft palate

26. Digeorge anomaly • Disturbance of cervical neural crest migration. • Absence of thymus and parathyroid glands • Immunological deficiency, Hypocalcaemia, Poor prognosis

27. DEVELOPMENT OF PALATE

30. Intermaxillary Segment Forms • Labial Components (Philtrum) • Maxilla Component (Alveolus + 4 Incisors) • Palatal Component (Triangular Primary Palate)

31. Secondary Palate

36. Congenital malformations 1) cleft lip: a. unilateral cleft lip: results from failure of the maxillary prominence to merge with medial nasal prominence on the affected side

37. b. bilateral cleft lip : results from failure of the maxillary prominences to merge with the medial nasal prominence on both sides c. median cleft lip: results from failure of the medial nasal prominences to merge and form the intermaxillary segments

38. 2) oblique facial cleft: results from failure of the maxillary prominence to fuse with the lateral nasal prominence

41. Thank You