INDIANAPOLIS - Justin Smith's recent triceps injury offered a glimpse into a future without the Pro Bowl defensive end, and it wasn't a pleasant one for the 49ers' defense.

Starting Dec. 16, Smith either was absent or favoring his left arm, and it had a ripple effect throughout the defense. Linemate Aldon Smith wasn't as effective (zero sacks in the final six games), inside linebackers Patrick Willis and NaVorro Bowman didn't have as much room to roam, and the secondary was bombarded against New England, Seattle, Atlanta and Baltimore.

Smith is expected to recover from his recent triceps tendon surgery, and he should be available for training camp. But he also turns 34 this year and is entering the final year of his contract.

Meanwhile, the 49ers haven't used a high pick on a defensive lineman since draft dud Kentwan Balmer was taken 29th overall in 2008.

All of that, plus the fact the draft is deep with defensive linemen, puts that position atop the 49ers' priority list at the scouting combine this week in Indianapolis.

The 49ers expect to have 14 selections in the April draft, with perhaps more if they can trade quarterback Alex Smith.

That should give them the ammunition to move up from the 31st spot if they find a player they believe can step into Justin Smith's role eventually and anchor their line for the next 10 years.

Here are some candidates for the 49ers:

• John Jenkins, 6-foot-3, 351, Georgia: He has the size to be a traditional nose tackle but is athletic enough to play all over the defensive line, which is what he did at Georgia and what NFL teams want from linemen.

• Datone Jones, 6-5, 280, UCLA: He is similar to current 49ers starters Justin Smith and Ray McDonald. Both entered the league in the 280-pound range but are around 300 pounds as defensive ends in San Francisco's 3-4 scheme.

• Jesse Williams, 6-4, 320, Alabama: Williams, a key in Alabama's defense, also played nose tackle and defensive end. He is freakishly strong and is expected to challenge the combine record in the bench press.

For the second year in a row, the 49ers also could target a wide receiver in the draft.

Michael Crabtree is a lock to start at one of the wideout positions. But there are questions about the No. 2 spot. Randy Moss and Ted Ginn aren't signed for 2013, and Mario Manningham and Kyle Williams are coming off late-season ACL tears. Last year's first-round choice, A.J. Jenkins, hasn't made a catch in the NFL yet.

Here are some options for the 49ers at wide receiver:

• Keenan Allen, 6-3, 205, Cal: He is considered one of the top receivers in the draft, but he still is recovering from a knee injury and won't perform at the combine. That and questions about his speed could push him toward the 49ers at the end of the first round.

• Cordarrelle Patterson, 6-3, 205, Tennessee: He has size, speed and elusiveness and can play on special teams. The only thing this community college transfer doesn't have is experience, having played only one season with the Volunteers.

• Tavon Austin, 5-9, 174, West Virginia: He has elite quickness and also could handle punt returns. He's one of the smallest players in the draft, but he also lined up at running back, which shows his toughness.

Finally, the 49ers need to address their depth at cornerback.

Starter Tarell Brown and backup Perrish Cox aren't signed beyond the 2013 season, and Carlos Rogers turns 32 in July. The team envisions Chris Culliver eventually taking over one of the starting spots, but they could use another young, big-bodied cornerback on the other side.

In their search for a cornerback, the 49ers could take a look at:

• Xavier Rhodes, 6-1, 215, Florida State: He's a prototypical press corner who matches up well against big receivers and can throw an opponent's passing game off rhythm. However, he's not expected to show elite speed at the combine.

• Desmond Trufant, 6-0, 185, Washington: While he doesn't have Rhodes' size, he is expected to be one of the fastest cornerbacks in Indianapolis this week. He also has impressive bloodlines - two older brothers are in the NFL.

• Johnthan Banks, 6-2, 185, Mississippi State: He has the height but a lanky frame. He set a school record with 16 career interceptions, most against quality Southeastern Conference opponents.

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