Defensive tackle Clifton Ryan, a starter the past two seasons before starting out 2010 as a backup, continues to be sidelined from practice because of what is believed to be recurring issues with migraines.
"We're not going to do anything until he feels right _ he's 100-percent right," coach Steve Spagnuolo said after Thursday's practice.
Ryan will miss his third consecutive game this Sunday when the St. Louis Rams play host to visiting Seattle.
Unlike past weeks, Ryan has not been seen this week during the open locker room sessions for the media. With second-year man Darell Scott still sidelined with a high ankle sprain, the Rams will try to get by with just three defensive tackles for the second game in a row.
Undrafted rookie Jermelle Cudjo is the only backup at the position behind starters Fred Robbins and Gary Gibson. In his first NFL game last week against Washington, Cudjo was in for 19 plays and had two tackles.
"He went in there and spelled the guys that were taking the bulk of the reps for us and did a nice job for us," defensive coordinator Ken Flajole said.
Besides, Ryan, Scott and running back Steven Jackson, also sitting out practice Thursday were safeties Oshiomogho Atogwe (thigh) and Darian Stewart (hamstring); tight ends Billy Bajema (knee) and Michael Hoomanawanui (ankle); linebacker Chris Chamberlain (toe); and wide receiver Laurent Robinson (foot).