Scrubs fans are used to seeing the cast sing, and yes, it’s really them singing on the episode. J.D. (Zach Braff) often sings during his daydreams; the hospital a cappella group makes frequent appearances; and in one memorable episode from the second season, “My Philosophy,” there’s a wrenching performance of a dying patient singing “Waiting for My Real Life to Begin.” This time, though, the songs aren’t through J.D.’s eyes, they’re through a patient’s. Scrubs prides itself on using real medical cases, and when the medical consultant for the show discovered a case where an aneurysm caused musical hallucinations, the writing staff found its story. (Curious? The journal article is called “Musical hallucinations associated with seizures originating from an intracranial aneurysm,” and it was published in the Mayo Clinic Proceedings.) When the patient’s around, everything is in song.

“We wanted to do an honest-to-God musical,” Lawrence says. “We wanted to sing the dialogue, have the drive, have it have some kind of emotional impact.” To that end, Scrubs writer Deb Fordham collaborated with Robert Lopez and Jeff Marx, the duo behind Broadway’s bawdy puppet musical Avenue Q, and with Paul Perry, who appears on the show as one of the members of Ted’s a cappella group, to come up with the ten-song score. Most of the songs are deeply reminiscent of different Broadway numbers. “All the modern musicals like Jekyll and Hyde have these really overwrought love songs, so we really wanted to have one between J.D. and Turk,” Lawrence says, and the result is the goofy duet “Guy Love,” which is already in wide circulation online. Other songs are takeoffs of “Be Our Guest” from Beauty and the Beast, numbers from Rent, Grease and Les Misérables, and a rant from Dr. Cox is a knockoff of “Modern Major General” from The Pirates of Penzance. “We were mortified because Studio 60 did [a ‘Modern Major General’ spoof] first,” Lawrence sighs, but then he pauses. “But theirs isn’t funny.”

What’s surprising about “My Musical” is that it’s a pretty straightforward episode. It’s flashy, sure, but it doesn’t deviate from the standard Scrubs model: J.D. meets a patient whose ailment becomes a metaphor for whatever personal issues he’s facing, and over the course of the episode, he realizes that he’s not the only one trying to make sense of the issue. In fact, every character is, in some way or another. There’s a breathless speech from Dr. Cox, some bickering between Turk and Carla, a heap of inside jokes between Turk and J.D., some high-strung neurosis from Elliot, mischief from Janitor, and so on. Just set to music.

“Every year, we do one high-concept show,” Lawrence says, like the fourth season’s “My Life in Four Cameras,” in which J.D. imagined Scrubs as a traditional multicamera brash comedy. “This was our big one this year.”

“My Musical” airs Thursday 18 at 8pm on NBC.