Monday, 4 August 2014

Development of Pharyngeal Arches, Faces and Tongue

by Lisa Wong and Wen Yun

1.  The trigeminal nerve gives three branches which is the ophthalmic, maxillary and mandibular branch.
2. Dorsal portion of the first pharyngeal arch  which makes up the maxillary process contains Meckel’s cartilage.
3.  During the development, Meckel’s cartilage persist and form the incus and malleus.
4.  Nerve supply for fourth and sixth pharyngeal arch is by vagus nerve.
5.  Muscles formed by third pharyngeal arch is the stylopharyngeus muscle.
6. Branchial fistulas occur when the third pharyngeal arch fails to grow caudally.
7. The anterior two-third of the tongue is formed by two lateral lingual swellings and one tuberculum impar.
8. Tongue musculature is innervated by glossopharyngeal nerve.
9. Taste sensory innervations of the anterior two-third is innervated by chorda tympani branch of facial nerve.
10.  Anterior two-third and posterior one-third of the tongue is separated by arytenoids swellings.
11. Ankyloglossia (tongue-tie), is due to the short frenulum attaching the tongue to the floor of mouth.
12. Second pharyngeal arch is also known as hyoid arch.
13.  The IXth cranial nerve is the vagus nerve.
14. The first pharyngeal cleft enlarges to form the external auditory meatus.
15. 3th , 4th and 5th pharyngeal clefts form cervical sinus which later is obliterated.
16. The first pharyngeal pouch endoderm enlarges adjacent to the first cleft to become the tubotympanic recess.
17. The third pair of pouches gives rise to two diverticula, dorsal and ventral. From the dorsal part of the pouch arises parathyroid III, which becomes the superior parathyroid gland.
18. All three embryonic layers are involved in facial development.
19. Facial development is completed during the twelfth week of prenatal development.
20. The stomodeum initially appears as a shallow depression in the embryonic surface ectoderm at the cephalic end.
21. The paired maxillary processes fuse at the midline to form the mandibular arch.
22. The paired medial nasal processes also fuse internally and grow inferiorly on the inside of the stomodeum, forming the intermaxillary segment.
23. The upper lip is formed when each maxillary process fuses with each medial nasal process.
24. The intermaxillary segment gives rise to the secondary palate.
25. The secondary palate will give rise to the anterior third of the hard palate.
26. The nasal cavity forms at the same time as the palate.

Ans:
1. T      10. F     19. T
2. F      11. T     20. T
3. T      12. T     21. F
4. T      13. F     22. T
5. T      14. T     23. T
6. F      15. F     24. F
7. T      16. T    25. F
8. F      17. F    26. T
9. T      18. T

       

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