While Scotland were in try-scoring form at Murrayfield, Muir were also in attacking mood just a couple of miles up the road, running in six against their visitors from Tayside.
The victory leaves them just four points behind second-bottom Stirling County in the RBS Premiership with five matches left to play.
Rob Cairns, Sep Visser and Sam Johnson all touched down for the home side as they built up a 17-0 lead in the first 15 minutes.
Harry Leonard and Jack Steele swapped penalties before Johnson grabbed his second try as Boroughmuir went into the break 25-3 to the good.
Malcolm Clapperton and Stevie Wilson added further scores after the interval, while Leonard kicked five points.
For the visitors, who came into this match off the back of a good win over Heriot's, points in the second half came through tries from Richie Hawkins, Brandyn Laursen and Steele with the latter converting one.
Gala moved to within two points of leaders Ayr by defeating Aberdeen Grammar 15-14 at Netherdale.
The home side took the lead after three minutes through a converted Luke Pettie try, but any suggestions of an easy afternoon were put to bed three minutes later when Tony McGuiness went over for the visitors. Rob Aloe converted to make the scoreline 7-7.
Erland Oag then scored Aberdeen's second try of the afternoon and there was a shock on the cards as they led 14-7 heading into the interval.
A penalty from Lee Millar dragged Gala back to within four points after 48 minutes and 10 minutes later Gary Graham scored what turned out to be the winning try from the back row.
In the other top-flight match played yesterday Edinburgh Accies returned from the Greenyards with a 20-19 win against Melrose.
The Borderers led 9-8 at the interval, Andrew Skeen kicking two penalties and Joe Helps one to an early penalty by Ruairidh Bonner and a try from skipper Dan Teague for the visitors.
Twelve points for Accies accumulated through tries from Nyle Godsmark and Iain Berthinussen and a Bonner conversion saw them lead 20-9 with 20 minutes remaining.
Melrose came back with an Alun Walker try and five points from the boot of Skeen, but it was not quite enough.