Pouch 1 is innervated by cranial nerve 5, pouch 2 by cranial nerve 7, pouch 3 by cranial nerve 9, and the rest by cranial nerve 10. In jawed fish, the cartilaginous arch goes to form the jaws. It goes to form our own embryonic jaws, which are later replaced by dermal bone except for the back ends of the jaw halves, which end up as bones in our middle ears.