When Argentina midfielder Javier Mascherano cracked heads with a Dutch player during a World Cup semifinal last week, millions of soccer fans saw it.

From all over the world, they posted comments about it on Twitter and Facebook — the Spanish words for concussion are conmocion cerebral, by the way — and some fans probably held their breath as they watched Mascherano’s reaction to the collision. He staggered for a few steps, as if he had downed one too many cocktails, then collapsed with a zombie’s blank stare.

Spectators did not need a medical degree to realize that he had hurt his head, and probably his brain, and that someone with a medical degree should properly evaluate him.

But then came yet another example of the dysfunction of FIFA, soccer’s world governing body, and how it apparently is indifferent to player safety, given what it has shown at this World Cup: Mascherano spent about two minutes on the sideline before returning for the rest of the match. That is about four or five minutes before he should have returned, if he had received a proper neurological evaluation to determine the extent of his injury.

This came about three weeks after Alvaro Pereira of Uruguay was knocked cold by a knee to the head during a first-round World Cup match against England, with many of those same millions of fans watching him as he lay on his back, unresponsive. The Keystone Kops treated his injury; trainers tried to slap him awake.

After waking, Pereira resisted leaving the field and played the final 30 minutes of the game. Later, he said, “the lights went out” after he was hit on the head.

Mascherano’s injury came about a week after the Brazilian star Neymar took a knee to the back in a quarterfinal match and fell to the ground, writhing in pain and saying he could not feel his legs. Medical workers went to him without a backboard and instead rolled him onto a stretcher. Then they jogged off the field with him jostling around and crying out with every step. One person even slapped his right leg several times.

Once again, no medical degree was needed to see that it was not the best treatment of someone who might have just sustained a serious spinal injury. Neymar, as it turned out, had broken a bone in his back.

It is a wonder what medical protocols FIFA enforces — if it enforces any at all — when the world is not watching. But it is a good bet that it would have snapped to attention if any of those players had faked an injury.

FIFA and fans have been shouting full-throated demands for rules changes to combat diving. Pretending to be injured to draw a foul is apparently a scourge that must be banished in the game at all costs. FIFA’s president, Sepp Blatter, has even suggested using video replay to punish it retroactively.

But injuries — including serious ones, like head injuries — have not seemed to bring about anything similar in terms of outrage. Players, who make the game so beautiful for its fans, deserve better. FIFPro, the world players union, knows that. It called for an immediate investigation by FIFA into how the Pereira head injury was treated, calling the problem of head injuries in the game “a ticking time bomb.”

That bomb could explode right in FIFA’s face, but it either has not noticed or does not care.

Whether FIFA plans to change how it deals with game-time concussions is unclear, but what is obvious is that it did not do anything quickly enough to protect players like Mascherano. His teammate Pablo Zabaleta also appeared to sustain a head injury in the game after smacking an opposing player, but he continued on.

This must stop. If FIFA or the game’s fans care at all about the players, they should complain just as loudly when a player with a head injury pops right back into a game as they do when a player nearly wins an Oscar by diving to draw a foul.

Right now, though, FIFA is showing its cowardice by saying the onus is on the team doctor to determine if a player is healthy enough to return to the match. It is as though FIFA has not been following the issue of head injuries in sports at all.

Even the National Football League, which for years ignored the seriousness of concussions, has learned that a doctor with no link to either team in a game needs to evaluate a player’s fitness after a head injury. Only that doctor can decide if a player heads back to the field.

The NFL has also learned the hard way — most recently through thousands of players suing it for concealing what it knew about the dangers of repeated hits to the head — that players with concussions should not play until they have fully recovered from their injury. But FIFA has that in its own guidelines, which it must have left back at headquarters in Switzerland.

For the players, there are huge risks of playing after a head injury, including second-impact syndrome, which can occur when a player with a concussion sustains another concussion before the first one has healed. The result could be fatal, though that is rare.

Is it going to take something that severe for FIFA to start caring about the players that have made its sport so rich?

Players who return to the game too early or have repeated concussions could also be setting themselves up for a lifetime of headaches, sensitivity to light and sound, and chronic fatigue. Taylor Twellman, a former player in Major League Soccer, has been struggling with those symptoms after a series of concussions ended his career. And that is why, after seeing how Pereira and Mascherano resumed playing after obvious head injuries, Twellman excoriated FIFA for acting as if it was living in the 1950s when it came to its medical care.

He called it barbaric and pathetic, but it is more than that.

For how much the sports world knows about concussions and how they can ruin the lives of players, FIFA has been irresponsible and callous in how it has treated its players at its biggest event.

Its own guidelines say: “Do not take a head injury lightly. No match is that important.”

Why even write that when you don’t really mean it?