Thornton had an MRI on Monday and missed a 3-1 win Tuesday against Vancouver, ending his streak of 201 consecutive games played.
"I had an MRI and everything looked good," Thornton said. "That was good news."
Thornton skated on his own for about 20 minutes before an optional practice. He avoided making hard stops or quick starts but took shots against goaltender Aaron Dell and tipped a few point shots from Brent Burns.
"I'm a quick healer," Thornton said. "Just a couple days, that's all I need. Who knows? Maybe I'll play tomorrow."
The Sharks play the Edmonton Oilers on Thursday at SAP Center (10:30 p.m. ET; NBCS CA+, SNW, NHL.TV) and the Calgary Flames on Saturday at home in their regular-season finale. San Jose (45-28-7) is tied with Edmonton for second place in the Pacific Division, four points behind the Anaheim Ducks. Edmonton has one game in hand.
The playoffs begin April 12.
"I'm pretty optimistic about things, so I never thought it was going to be too, too bad," Thornton said. "The training staff didn't think so either. They just told me a day-to-day type thing. I felt good today. It was good skating. So we'll see if it feels good tomorrow morning."