The San Francisco 49ers will have the option of bringing back two players from the injured reserve list later during the season. Third-year defensive end Arik Armstead will not be among those two players, according to head coach Kyle Shanahan, who discussed the situation on KNBR Friday.

Armstead broke his hand during the first quarter of Sunday's loss to the Washington Redskins and was placed on injured reserve on Tuesday. The defensive lineman defended his toughness on Wednesday in response to fans on Twitter saying he should simply play with a cast over the hand. Defensive coordinator Robert Saleh also responded to the criticism on Thursday.

The injury was originally thought to have taken place in the second quarter because Armstead remained in the game until that point.

"Arik played a quarter-and-a-half (against Washington) with that broken hand," Saleh said. "He's a tough son of a B. He is. He's tough and I will never question that man's toughness. If he could have played with a club, he would have played with a club. If he can play with one hand, he'll play with one hand."

Shanahan offered a little more insight into Armstead's injury.

"He really wanted to play with a cast," Shanahan said. "I know he's done it before in college and I was hoping he could and our doctors. The type of break he had, a cast doesn't do anything for it. I'm not exactly sure the medical terms but he broke his hand and his knuckle went down into his hand so it's something that a cast could not protect.

"I heard people were questioning his toughness with it, which it was exactly the opposite. He broke his hand in the first quarter, played the whole first half. You can see on tape, he's playing with his hand flopping around. I know he was real disappointed that he couldn't play the rest of the year but you've got to go with what the doctors tell us and we're going to have to put him on IR (which was done on Tuesday)."

Shanahan was asked if there is a chance that Armstead could return by the end of the year and the head coach explained that the plan is to hopefully bring back defensive linemen Ronald Blair and Tank Carradine. Therefore, Armstead's return this season, while possible, is unlikely.

"Once you get those two, you can't have anymore," Shanahan said, "and I think the minimum of Armstead is six weeks. That will only leave us the last three games so there's a chance but I'd say it's an outside chance."

You can listen to the entire interview with Shanahan below.

Armstead was the 17th-overall selection by the 49ers in the 2015 NFL Draft. He started all six games this season and had 16 total tackles, 1.5 sacks, and a pass defensed. Over his three seasons with the 49ers, Armstead has 50 total tackles, six sacks, and a pass defensed.