In one of the numerous battle scenes of “X-Men: Last Stand,” the walking mountain that is the Juggernaut plows through wall after wall in pursuit of youthful X-Man, Kitty Pryde.

Once Juggy reaches his target, the sprightly Pryde bates him into chasing her yet again — only this time, he runs head-first into a wall (his powers dampened by another mutant, Leech), knocking himself unconscious.

The same could be said of “X-Men: The Last Stand” — a noisy, busy, spectacle-filled movie that looks impressive and is full of “wow” moments, but ultimately runs into a wall that it can’t get through — poor direction.

Brought to thoughtful cinematic life in 2000 by director Bryan Singer, the X-Men went public (outside comic book shops, that is) as an intelligent, layered source material filled with believable characters and motives.

Singer upped his own ante in 2003 with “X2: X-Men United,” introducing even more characters and digging deeper into back-stories and the characters’ psyches.

With “Last Stand,” “Rush Hour” director Brett Ratner takes over directorial duties, subscribing to the “more is better” Hollywood school of thought — shoe-horning in dozens of new characters, compounding the frenetic action sequences, and breaking up the editing to sometimes look like an X-Men music video (without the music).

While the movie does entertain, it squanders genuine story and character development for explosions and chase scenes.

Two key plots of “Last Stand” come from the discovery of an anti-body which can allegedly “cure” mutations and restore mutants to “normalcy,” and the revelation that psychic Jean Gray (Famke Jannsen), thought dead at the end of “X2,” is alive and not quite right in the head.

Apparently, Gray had exhibited potentially dangerous telekentic/telepathic powers as a youth (shown in a clever flash-back with a younger Charles Xavier and Magneto, played with grace by Patrick Stewart and Sir Ian McKellan). Xavier believed it best to suppress Gray’s dangerously uncontrollable powers through psychic barriers (or something), which disappeared when she came back from the dead.

Or something.

The very-much-alive Gray, or “Dark Phoenix” is a schizophrenic she-devil — detached and voracious in her appetite for destruction.

The upshot of both plots leads to inevitable conflicts between the mutants in Magneto’s (literal) camp of “striking with fury that the world has never witnessed” and mutants in Xavier’s camp, who teaches tolerance and compassion — it’s Malcom X vs. Martin Luther King Jr., only as mutants.

While there are plenty of surprises for X-Men fan-boys, the growing cast of central characters (now up to 16!) seem to be fighting for screen time almost as much as they are against Magneto and his minions.

Major characters, most notably Cyclops (James Mardsen) and Rogue (Anna Paquin) have so little screen time, they’re given little more than glorified cameos.

Of the new cast, Kelsey Grammar turns in an impressive performance as the articulate, dexterous, blue-furred Hank McCoy, aka “Beast,” and Ellen Page (”Hard Candy”) is a stand-out among the new cast as Kitty Pryde, although she’s given little more to do than flirt with Iceman (Shawn Ashmore) and run from the unstoppable Juggernaut (Vinnie Jones).

“Last Stand” certainly doesn’t sink the “X” franchise, but it’s certainly showing signs of taking on water.

While not bad, the movie hardly warrants more than a lukewarm recommendation for all but die-hard X-fans, and even they will most likely be distracted by the inconsistencies in the movie versions of the characters.

Note: Parents should strongly heed the movie’s PG-13 rating — the language is strong and frequent, as is the violence, and Phoenix and Wolverine share a surprisingly intense (clothed) foreplay scene, interrupted only by Phoenix telekinetically throwing Logan into a wall — always a mood-killer.

Despite the new characters, the flash and the action, the movie ends on a depressing note. It’s giving little away to say that there are deaths in “X3,” and not whom you’d expect.

While execs have gone on record that “Last Stand” will be the final movie in the series, it would be unfortunate to see the property end on such a dismal note.

As a general rule, sequels usually diminish the gloss of the earlier movies, but after “Last Stand,” one can’t help but think the characters deserve at least one more good movie.

Perhaps after “Superman Returns,” Bryan Singer will return to the X-fold as director, ending the series as it began — with a core group of characters who may not be human, but who exemplify humanity and hope in a world that fears and misunderstands them.