Washington Redskins defensive end Markus Koch's injury to his right knee was diagnosed as a sprain of the medial collateral ligament.

The severity of the injury is unclear, although he had little swelling when he reported to Redskin Park for treatment yesterday. He's listed as questionable for Sunday's game with the Giants, but has told coaches he believes he'll be able to play.

"That'll be something we'll wait until later in the week on," Coach Joe Gibbs said. "The doctors think it's going to be iffy this week. Markus is probably a little more positive the other way. He thinks he has an outside chance of going."

If the Redskins believe Koch will miss more than one game, they'll probably place him on injured reserve and activate Jumpy Geathers from the physically unable to perform list. "It depends on our overall health," Gibbs said. "We want to get Jumpy up, but it'll depend on what we think is best." All Misses Not Chip Shots

Gibbs said watching films offered no explanation as to why kicker Chip Lohmiller missed four field goals on Sunday. He missed from 51, 48, 41 and 50 yards. Three of them were out of his best range, but the 41-yarder was a bad kick.

"It was just one of those days," Gibbs said. "I thought Chip was hitting the ball fairly solidly with the exception of one of them. He banged them all and that's what you're looking for. With kickers, by the time you psychoanalyze everything, the next week they can't hit anything. I tell them to tee it up and hit it as hard as you can. Some are going to go through and we may miss some." Caldwell Working Hard

Linebacker Ravin Caldwell, who lost his job to rookie Andre Collins during training camp, was singled out for praise by Gibbs.

"He's making his presence felt," Gibbs said. "He came into camp and I could tell he was worried about his knee. I don't think he was in real good shape. I think he was afraid to work out hard. He made several big plays and we're going to try to play him more." Marshall Can Take a Hit

One of Sunday's hardest hits was a block put on linebacker Wilber Marshall by Eagles running back Keith Byars.

But Marshall jumped back up after the play and said he told Byars, " 'You're going to have to hit me harder than that.' He was amazed I got up. If that's the best he's got, he's going to have to come with some more." Redskins Handling East

The Redskins, who were 4-4 against NFC East opponents last season, are off to a 4-1 intradivision start this season. . . . Earnest Byner is fifth in the NFC in rushing with 345 yards while Gerald Riggs is ninth with 291 yards . . . The Redskins still haven't lost a fumble on offense this season. Since finishing the 1988 season last in turnover differential (minus-23), the Redskins are plus-12 in their last 22 games.

Ricky Sanders has seven touchdown catches in nine games against the Giants. . . . The Redskins' 43.8 percent third-down conversion rate trails only San Francisco (52.7) in the NFC. . . .

Annette Rypien, the wife of quarterback Mark Rypien, gave birth to a seven-pound, one-ounce daughter -- Angela Sue -- yesterday morning. . . . The Redskins said fans donated enough nonperishable foodstuffs upon entering RFK Sunday for the game against Philadelphia to provide as many as 13,000 meals for area shelters.