The double-double was the sixth of the year for Muscala, while Joe Willman scored a career-high 19 points. Bryson Johnson added 12, Cameron Ayers 11 and Brian Fitzpatrick 10 for the Bison (8-5).
The Terriers (4-8), who have lost four straight, led by four early and still held a 17-16 lead with 11:34 to go before halftime. Fitzpatrick then scored five points on a 7-0 spurt to give Bucknell a lead it never relinquished.
The Bison led by as many as 19 in the first half, shooting 64.3 percent from the floor (18 of 28) with only one turnover.
Boston University, led by Darryl Partin with 17 points, could get no closer than 14 after the break. The Terriers had only five first-half boards and just two offensive rebounds the entire game.