The defender is one of four signings made by boss Jackie McNamara this summer as the Jags gear up for a shot at the Irn-Bru First Division title next season.
Muirhead and fellow new arrivals Sean Welsh, Hugh Murray and Steven Lawless began life as Thistle players on Monday as McNamara put his squad through their paces for the first time ahead of the big kick-off.
The former Annan youngster has thrived in the Third Division in recent years and is relishing the challenge of forcing his way into McNamara's plans.
He said: "The boys have made me very welcome.
"It was a little different in the fact that previously I trained just twice a week and here I've come in and I've been thrown into a double session right away.
"Training every day, and training under the likes of Jackie McNamara and Simon Donnelly, who know a lot about the game, should really help bring my game on.
"I know a couple of the boys anyway and I've moved in with Christie Elliott and he was very good at introducing me to the boys."
With the first week of pre-season almost finished, McNamara's side will soon head for familiar surrounds as they continue their preparations for the new term.
The Jags boss will take his players to the Catterick Garrison in Yorkshire on Monday for a week of intensive training before they play their first friendy fixtures next month.
Muirhead admits the schedule has been punishing so far, but the youngster knows his hard work will all be worth it when the competitive action comes around.
The 21-year-old said: "It was quite tough, but it is good to get all the rubbish out of your system. My legs are a bit stiff, but I suppose most of the boys will feel the same.
"This is the part of pre-season where you put in all the hard work and hopefully see the benefit of that hard work once the games start."