1 - embryology

Question 1

what (in general) does ectoderm, mesoderm, endoderm result in?

Answer 1

ectoderm = surface coverings (skin)
mesoderm = MSK stuff like bones, muscle, cartilage
endoderm = inner linings like gut tube & lining of stomach

Question 2

what nerves supply the 1st, 2nd, 3rd, 4th&6th pharyngeal arches?

Answer 2

• 1st = CN V (trigeminal), mandibular & maxillary divisions
• 2nd = CN VII (facial nerve)
• 3rd = CN IX (glossopharyngeal nerve)
• 4th&6th = CN X (vagus)

Question 3

what do the 1st, 2nd, 3rd, 4th&6th pharyngeal arches? (just like basic)

Answer 3

1st = forms maxilla, zygomatic, temporal & incus+malleus bones. also forms muscles mastication

2nd = stapes, temporal bone, hyoid bone.also facial muscles

3rd = hyoid bone, stylopharyngeus muscle

4th&6th = laryngeal cartilages, muscles of larynx

Question 4

what do the 1,2,3,4 pharyngeal pouches form?

Answer 4

1st pouch →forms middle ear

2nd pouch →forms palatine tonsil

3rd pouch →forms thymus & inferior parathyroid gland

4th →c-cells of thymus (ultimobranchial) & superior parathyroid

Question 5

what nerve supplies anterior 2/3 tongue?

Answer 5

mandibular branch of trigeminal nerve (general sensory) and facial nerve (special sensory)

Question 6

what nerve supplies posterior 1/3 tongue?

Answer 6

glossopharyngeal nerve (CN IX)