A neighbor's child came home from nursery school his first day and became instant legend in our community. "What did you learn," the 3-year-old's mother asked? "I learned the rules," he said, "no hitting, spitting or bitting . . . ."

Nobody doubts the social worth of such a rule in any setting, but some of the health ramifications may bear repeating.

Especially to "hitting" and "bitting" there may be more than meets the, well, fist or, perhaps, tooth. (And neither punch-out nor bite is limited ot nursery school . . . even if the latter is later more accurately pronounced.) HITTING:

According to a group of southern orthodontists, a child's jaw can be permanently thrown out of sync as the result of the fracture of small bones where the jaw joins the skull.

What can happen, the dentists warn, is that one side of the lower jaw grows more than the other, giving a lopsided appearance.

They recommend that any child who has pain or soreness or stiffness in cheeks or jaws after "a fall, bike wreck or fist fight" see a dental specialist. The tiny bones are fragile and can break with only moderate pain, but the long term consequences may be more serious. BIT(T)ING:

Human. Folk wisdom has always held that a people bite is worse than a dog bite. This is not strictly true, but doctors do know that human saliva contains bacteria which can cause serious bone and tendon infections. The wound may not look serious enough to bother with, but the infection, harmless in the saliva, can, for example, cause loss of the use of a hand. Any human bite should be seen by a doctor.

Dogs. Dog bites are bad enough. The teeth may not be as sharp as those of say, a tiger, but the jaws can exert enough pressure to pierce sheet metal, according to a report from the University of California Medical School in San Francisco. Dog bites, perhaps a million a year, account for 1 percent of all hospital emergency room visits, the report said.

Rabies, of course, is the paramount concern with dog bites, although a new treatment available in this country since last summer carries with it much less trauma than the series of shots that used to be required. However, contrary to conventional wisdom, dogs do not have clean mouths and dog bites can very easily become infected.

Raccoons and other animals. Rabid raccoons have been found this summer in Virginia and West Virginia, the Center for Disease Control has warned. Four diseased animals were captured near Front Royal in the Shenandoah National Park. Previously raccoons carrying rabies were seen mostly in states some 300 miles or more to the south -- South Carolina, Georgia, Alabama and Florida.

If you see a raccoon or other nighttime animal out during the day, or acting strangely, or even acting friendly -- which is strange for wild animals, call your local animal control center or a state forest and wildlife office or, if someone has been bitten, a public health officer. Don't wait. When in doubt, call.

Doctors like to have diseases they discover named after them -- one step to immortality, you might say.

But lately the pages of medical journals have been chock full of some of the dippiest disorders yet. And nobody's running to get their name tacked on to them, either. One doctor, though, named his ailment for his dog, Hogan. Here are some of the latest:

Hogan's elbow. Hogan is a black Labrador. Labs are loves, but can get frisky at the end of a leash. And are they strong!

Hogan, writes Dr. William Mebane, his owner, "tugs constantly to sniff most bushes, poles, trash containers, fireplugs and dogs, both male and female." Mebane is also the owner of the inflamed left elbow which now bears Hogan's name. The tugs put pressure on the bone, made it sore and kept it that way.

Surfer's Knots. Lumps on the ankles and shins of surfers come from kneeling on the rough surface of the board, wrote Dr. Claude Burdick to the Journal of the American Medical Association. Related to housemaid's knee, they sometimes go away by themselves. Sometimes they need medical attention.

And from Alaska come these:

Musher's Knee. From the backward kick of the driver of the dog sled.

Hooker's Elbow. Not what you think.This happens to people fishing in the ice. It comes from repeated jerks of the fishing line through a hole in the ice.

And doesn't that sound like a nice thing to be doing this week?