Brachial arch abnormalities and comments

Question 1

1st arch

Answer 1

Treacher collin syndrome: 1st-arch neural crest fails to migrate => mandibular hypoplasia, facial abnormalities

Question 2

3rd arch

Answer 2

Congenital pharyngocutaneous fistula:
persistence of cleft and pouch

=> fistula between tonsilar area, cleft in lateral neck

Question 3

4th-6th arches

Answer 3

Arches from 3 and 4 form posterior 1/3 of tongue

Arch 5 makes no major developmental contribution.