Thornton was 6 of 6 from the field and one missed free throw away from a perfect shooting night for the Trojans (6-3), who have won three of four.
Tim Stewart scored 10 points to lead the Panthers (0-13), an NAIA team whose campus is about 5 miles away from the Trojans'.
Arkansas-Little Rock led 42-25 at halftime, shot 58.5 percent and outrebounded Philander Smith 47-31.
This was the first meeting between the neighboring schools since the 1969-70 season. The Panthers still lead the all-time series, 4-3.