Dev't of Face & Oral Cavity

Question 1

1. Facial Clefts:

Answer 1

• Large group-deficient medial nasal prominences
• Smaller group-underdevelopment of the maxillary prominence.
• Primary palate + secondary palate = 2/3 patients
• Secondary palate = second most frequent
• Failure of fusion or merging between facial prominence of reduced size = less frequent

Question 2

2. Hemifacial Microsomia:

Answer 2

• Underdev’t on one side = 1/5000 births
• aka Goldenhar syndrome = eye of both sides of face, asymmetry of face w/ mal-ear and underdeveloped jaw on affected side. (abnormal bite, hearing loss, psychosocial issues)

Question 3

3. Treacher Collins Syndrome:

Answer 3

• Bilateral combination of clefts thru malar and lateral orbital bones = 1/25,000
• flattened cheek prominence, downward slanting deficient lower eyelids
• airway, occlusion, hearing and abnorm of eyelids

Question 4

4. Labial Pits:

Answer 4

• Small pits on either side of midline of lower lip

- failure of embryonic labial pits to disappear

Question 5

5. Lingual anomalies:

Answer 5

• result of persistance of tuberculum impar

- bifid tongue

Question 6

6. Developmental Cysts

Answer 6

• epithelial rests in lines of union may give rise to cysts lined w/ epithelium. The rest of epithelium in visceral arch area, laterally disposed on neck
• globulomaxillary cysts-arise after fusion of medial, maxillary, lateral nasal prominences.
• anterior palatine cysts-midline of maxillary alveolar prominence
• nasolabial cysts-base of wings of nose and bulging into nasal and oral vestibule and root of upper lip

Question 7

Embryo Dev’t

Answer 7

• Epiblast → mesoblast → hypoblast

- endoderm (1st) → mesoderm (2nd) → ectoderm (3rd)

Question 8

1. Dev’t of nasal placodes, frontonasal region, primary palate, and nose:

Answer 8

• Thickening of surface ectoderm on either side of frontal prominence to form nasal placodes
• induced by ventral forebrain.
• Nasal (olfactory) pits located on either side of frontonasal prominence surrounded by horse-shoe-shaped eminences (medial nasal process-MNP) (Lateral nasal process-LNP)
• Primary palate (median palatine process)-the anterior aspect of this partition is derived from the area of the upper jaw formed by the lateral, medial nasal processes(intermaxillary segment).

Question 9

2. Dev’t of maxillary prominences and secondary palate

Answer 9

• Medial growth of shelf-like processes called the palatine shelves (lateral palatine shelves) forms secondary palate.
• Nasal septum + 2palatine shelves = right & left nasal chambers
• hard palate + soft palate = secondary palate

Question 10

3. Dev’t of visceral arches and tongue

Answer 10

• 6 visceral arches in humans
• 1st arch-C5(Trigeminal) , 2nd arch-C7(Facial), 3rd arch-C9(glossopharyngeal), 4th arch-C10(Vagus)
• Tongue:
• First arch = 2lingual swellings+tuberculum impar (anterior 2/3 of tongue-ectoderm)
• 3rd arch = hypobranchial eminence (posterior 1/3 of tongue-endoderm)