DEVELOPMENT OF TONGUE THYROID GLAND, FACE AND PALATE
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Transcript of DEVELOPMENT OF TONGUE THYROID GLAND, FACE AND PALATE
DEVELOPMENT OF TONGUE
THYROID GLAND, FACE AND PALATE
By Dr Samina Anjum
PHARYNGEAL ARCHES
• 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
TONGUE TIE
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
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
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.
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
Thyroglossal Duct Cysts & Sinuses
Following infection of a cyst, a perforation of the skin occurs forming a thyroglossal duct sinus
Lingual Thyroid
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.
Craniofascial Defects
• Treacher Collin’s syndrome• Robbin’s sequence• Digeorge anomaly• Goldenhar syndrome
First Arch Syndrome
Two Major types; both result in extensive facial abnormalites
1. Treacher Collins Syndrome
2. Pierre Robin Syndrome
Treacher Collins Syndrome
• Autosomal dominant trait/teratogens
• Malar hypoplasia• Mandibular hypoplasia• Down slanting palpepebral
fissures• Malformed external ears
Pierre Robin Syndrome
• Genetic or envoirmental factors
• Mandibular hypoplasia• Micrognathia• Cleft palate
Digeorge anomaly
• Disturbance of cervical neural crest migration.
• Absence of thymus and parathyroid glands
• Immunological deficiency, Hypocalcaemia, Poor prognosis
DEVELOPMENT OF PALATE
Intermaxillary Segment Forms
1. Labial Components (Philtrum)
2. Maxilla Component (Alveolus + 4 Incisors)
3. Palatal Component (Triangular Primary Palate)
Secondary Palate
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
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
2) oblique facial cleft: results from failure of the maxillary prominence to fuse with the lateral nasal prominence