“The Muppet Movie” holds up almost better than it has any right to. Yes, there’s the nostalgia factor, those warm childhood memories of watching Kermit, Fozzie, Miss Piggy, Gonzo and the rest on evening TV, memories that would probably make us adore the movie even if it didn’t meet our adult expectations.

But, in fact, “The Muppet Movie” does meet our adult expectations — and then some. A movie that’s as good-hearted, silly and childlike as it is subversive, absurd and progressive, “The Muppet Movie” is one of those rare television-to-movie adaptations that gives a back story but dips and swerves into so many different experiences that you hardly feel like you’re watching anything remotely television-like. Which truly was in the spirit of the TV show — there was nothing quite like it.

And there never was (or has been) anything like “The Muppet Movie.” The picture (the first of a series of live-action movies featuring Jim Henson’s famed creations) works as a road movie, wherein croaker Kermit leads the story of how the Muppets found each other. Kermit is a simple boy frog living an idyllic life in a swamp, where he plays his banjo and sings — most memorably the lovely “Rainbow Connection” (written by Paul Williams), a song that nearly rivals “Moon River” in its bittersweet beauty.

After he’s encouraged to follow his dreams (by, of all people, Dom DeLuise, who just happens to be hanging around the swamp), a road trip ensues (starting with Kermit on his bike — a sight that nearly knocked me out of my theater seat as a child). Kermit’s off to Hollywood, but not without speed bumps along the way, chief among them a predatory businessman (Charles Durning) who seeks the talented Kermit to represent his frog leg empire.

After fantastic musical numbers, many adventures, numerous close calls and memorable celebrity cameos (including Steve Martin, Richard Pryor, Bob Hope, James Coburn, Madeline Kahn and Orson Welles), Kermit realizes that the world outside of the swamp isn’t exactly like him — sweet. But when looked at with the right spirit, it’s not all that bad, either.

The most charming leap from TV to the big screen, “The Muppet Movie” is an unusual but ultimately poignant picture that is, for some of us adults, even more touching today.