Phil Foden added a third, latching onto a ball into the box from Fernandinho and lifting it over the advancing Runarsson.
Aymeric Laporte then headed in a Foden cross to wrap up the win for Pep Guardiola’s side as they added to the troubles of the Gunners who are languishing in 15th spot in the Premier League, only four points above the relegation zone.
Arteta had declared before the game that he wanted to see “fighters” and not “victims” and he said that despite the result he saw the fighting spirit he needs to turn the season around.
“I will focus on the fighters we have in the squad and the spirit we showed tonight against a really difficult opponent. I see a lot of fighters,” he said.
Arteta was assistant at Manchester City before he joined Arsenal a year ago and Guardiola defended him from his critics.
“What can I say – in our position as a manager we’ll be judged by the results. I can only say I was with him a long period, the most successful period our club had.
“Sometimes in our job we need time. It’s time to be patient. He’s an outstanding manager, incredible work ethic and puts the club in front of any decisions he has to make,” Guardiola said of his fellow Spaniard.
City joined Brentford in the semi-finals after the second-tier side enjoyed a 1-0 win over Premier League Newcastle United earlier in the day.
In the remaining two quarter-finals, Everton host Manchester United and Championship team Stoke City welcome Jose Mourinho’s Tottenham Hotspur on Thursday.