Handel + Haydn violinist Aisslinn Nosky is a master of her trade, a concertmaster, to be precise. The title, from the German word “Kapellmeister,” is one composers like Bach and Haydn once held. It’s a role that not only requires expertise in the violin—which she’s played since age 3—but also in tuning the orchestra and marking sheet music. “It’s a little bit like I’m a middle manager, a bridge between the rest of the string players and the conductor,” she explains.

On April 4 (Jordan Hall) and April 6 (Sanders Theatre), she’ll take on another role, leading her Handel + Haydn peers in Mendelssohn’s Library without artistic director Harry Christophers at the helm. But as Nosky notes, “Having a conductor in front of an orchestra really didn’t start to become a standard affair until the late-18th and, actually, well into the 19th centuries.” She proposed the program to highlight some of the German composer’s lesser-known works, as well as music that inspired him. Mendelssohn was an avid collector of autographed works by composers such as Mozart, Handel and Vivaldi—unusual at the time—and Nosky says these influences can be heard in his music.

On stage, she’ll be joined by associate concertmaster Christina Day Martinson and assistant concertmaster Susanna Ogata. The three women hold the top orchestral positions—a rare occurrence. “I think we are, in one sense, blind to the gender issue because we’re trying to make decisions based on what’s really good for the art,” Nosky says.

Also unique is the baroque group’s staying power: Next year, it celebrates its bicentennial. Nosky, who joined H+H in 2011, is happy to help keep its tradition alive. “Knowing there’s that history behind us gives me confidence, but it’s also very humbling,” she says. “We have a huge responsibility to do whatever…it takes to get this wonderful music out to people for the next 200 years.”