“Jack fell down and broke his crown”….

And then he was dead.

Yes, I know the “Jack and Jill” poem doesn’t end that way, but life isn’t a children’s fairy tale.

Our Thanksgiving holiday was marred by the funeral of a very close friend I have known since I was 22.

Saddest of all, Jack’s death was needless.

My husband and I still cannot process this tragedy. We visited Jack and his wife at their New Jersey shore home on a sunny October day. The very next morning, Jack fell in a parking lot.

A day later, on their wedding anniversary, he and his wife and four friends boarded a cruise ship to Bermuda.

Unbeknownst to anyone, the fall had injured Jack’s brain and slow bleeding had begun.

Two weeks after the cruise, Jack collapsed and the bleeding brain was discovered. By then, medical intervention was too late.

He never regained consciousness and could not live without a tangle of life support equipment.

The nightmare reminded me of other such cases.

I recalled the actress Natasha Richardson, who hit her head in a skiing accident. She walked away, talking and laughing, and hours later was dead.

Closer to home, a few years ago my friend Judy fell off the bed she was standing on to adjust a ceiling fan.

When her head slammed onto the hardwood floor, Judy said she had a headache but thought little of the incident.

Late that night she became dizzy and nauseated, prompting a visit to the emergency room. Blood was collecting in her brain and had to be drained. A hole was drilled in her head and a tube inserted.

Judy was in the intensive-care unit for about a month and needed rehabilitation therapy. But, unlike Jack, she lived.

My niece’s in-laws went out to dinner one night. Little did they know it would be the last time. As they left the restaurant, her father-in-law fell in the parking lot, hitting his head. He died immediately of a brain injury.

Lessons learned: We can’t mess around with the brain. If we fall or bang our heads, we need medical attention, even if we think we are okay.

Medical research of subdural hematomas, blood clots that grow under the skull and put pressure on the brain after a head injury, shows a high mortality rate, even with excellent medical care.

Although head trauma is a major cause of the disorder, indirect trauma that jostles the brain is even more common.

Aging plays a role, too, since the brain shrinks as we grow older, creating a space where fluids can collect.

Our veins travel through this space as they drain the brain, and even a slight jolt can cause these veins to leak, which traps blood against the brain.

Usually a CT scan can reveal or rule out a subdural hematoma.

A correct diagnosis is crucial, because if bleeding into the brain’s subdural space continues, the increased pressure on the brain can cause loss of consciousness, permanent disability and even death.

We cannot minimize brain shrinkage as we age, but we can control other causes of subdural hematomas, such as falls.

As we age, balance and aerobic exercises become important in helping us to maintain our muscle strength and stay on our feet.

Avoiding head injuries in the first place should be our major goal, of course.

But since we often have no way of knowing when there is something wrong inside our heads, it is best to play it safe and seek medical attention when we suspect a head injury or notice sudden unusual neurological symptoms, sometimes misdiagnosed as dementia or stroke or Parkinson’s disease.

Jack in the nursery rhyme and my late friend Jack fell down and broke their “crowns.”

Both stories should have had happier endings.