Stoke claimed a 1-0 win over Hull at the Britannia Stadium thanks to a Peter Crouch header, although Bruce felt the striker scored from an offside position.
Hughes was angered by Figueroa's tackle on midfielder Ireland, who was forced off with a gaping wound in his calf - a picture of which has since gone viral on social media - having previously escaped punishment for a challenge of his own on David Meyler.
In a news conference on Monday, Bruce said: "Stephen Ireland committed the worst challenge on the pitch on David Meyler.
"I could take you a picture of Figueroa's ankle, he had five stitches in his on Saturday and carried on.
"Nobody wants to see a cut or someone being injured as badly as Stephen Ireland is, but unfortunately in football it happens.
"Maynor has kicked the ball and has followed through and unfortunately he's caught his [Ireland's] leg. If we really want to go and show the challenge Stephen Ireland committed on David Meyler, then for me he shouldn't have been on the pitch."
Hull face Bruce's former club Sunderland at the KC Stadium on Tuesday in a game that could have a significant bearing on the fight for Premier League survival.
Sunderland currently occupy 16th position, three points above the relegation zone and one behind Hull.
"It gives us a wonderful opportunity of putting some daylight between ourselves and Sunderland [and the teams] in the bottom three," Bruce said.
"If we take that opportunity, it's a tremendous platform for us which is always good with 10 games to go.
"If we can go and win [on] Tuesday and put seven or eight points between us and the bottom three, that's huge."
Asked about his points target for survival, Bruce added: "Usually 36 is [enough]. We always say 38, some say the magical 40. We've got to get enough to make sure we stay here."
