The Washington Redskins, needing depth at tight end because of injuries, yesterday signed five-year veteran Walt Arnold, who recently was cut by the Houston Oilers.

The Redskins went shopping for a tight end following Sunday's injury to reserve Mike Williams, who suffered a hairline fracture of his neck during special teams play in the 35-17 loss to Miami. He is expected to be out for six to eight weeks.

Clint Didier, injured in the preseason, is on injured reserve and can not return until at least the fifth game of the season. That left Washington with only rookie Anthony Jones as a backup at tight end.

Arnold, 26, played his first two years in the National Football League with the Los Angeles Rams and the last two with the Oilers. He was among Houston's final cuts this year.

It was the third time that Arnold, who is 6 feet 3, 225 pounds, has been released. He was among Houston's final cuts in 1983, but was re-signed early in the season and played in the Oilers' last 13 games. He was surprised to be cut last week.

"I feel I can play, and I thought I had played well in the preseason, but I was not by any means thinking about quitting football," Arnold said.

In the past week, however, he had thought about continuing his offseason real estate career or returning to the University of New Mexico for the 18 credit hours needed for his degree.

Arnold, a four-year letterman in baseball and a three-year letterman in football at New Mexico, averaged 11.5 yards per catch on 12 receptions last year. In 1981, he started nine games for the Rams and caught 20 passes for a 10.6 average and two touchdowns.

Last year, and this year under new Coach Hugh Campbell, the Oilers used a two-tight end system similar to the one used by the Redskins. Arnold was primarily the tight end in motion, which is the "receiving" tight end in Houston's offense.

Washington Coach Joe Gibbs gave the team a day off yesterday, but met with Arnold at Redskin Park. He said Arnold would be used to back up Rick Walker.

"We felt he was the best player available at this time," Gibbs said.

Gibbs also explained why rookie Jimmy Smith was cut Monday.

"From the final preseason game and the week after, we thought he was losing his confidence," Gibbs said. "As time went on, that turned out to be the case."

Gibbs said rookie Keith Griffin, another running back, would move into Williams' position of returning some kickoffs and punts.

The San Francisco 49ers will be starting reserves at each cornerback position Monday night when they are host to the Redskins, Coach Bill Walsh said yesterday.

Within the first four plays of Sunday's 30-27 victory over Detroit, right cornerback Eric Wright and left cornerback Ronnie Lott were injured. Wright is out three to five weeks with a strained left knee. Lott, who will be on crutches until Friday with a badly sprained right ankle, said yesterday he hopes to play, but Walsh said later that Dana McLemore would start.

Defensive end Jeff Stover also was injured and will miss Monday's game. He was replacing holdout Fred Dean. Three 49ers went to the U.S. Football League in the offseason, meaning only five defensive players who started against the Redskins in the 1983 NFL championship game would start Monday.

"We are going to have to play a little softer and be in a position to make the stops and prevent the big plays this week," Walsh said. "Our only hope is to keep the Redskin offense off the field as long as possible. I hope it's not a high-scoring game because the Redskins usually win those type. If we can get 24 points, I'll feel very fortunate."