4 yr old fell back onto concrete; hit head, but was somewhat braced by arm. showing no signs of concussion, & is running around. take to dr?

Yes!: An epidural hematoma is caused by a blow to the head, in the temple area. These involve bleeding that is initially confined between membranes within the skull cavity, so a person may appear totally normal at first. Undiagnosed and untreated, pressure builds, can be rapidly fatal. (natasha richardson ring a bell?) bleed around brain (subdural hematoma) can cause delayed mental status changes. C md.

Observe: Its ok to just observe, if the child looks tired or confused or if there is vomiting, go to the er.

Depends: By definition a backward fall has limited momentum & bracing negates some of the impact. If into a corner or edge with a visable defect, a period of loss of consciousness, dizziness or disorientation or recurrent vomiting, i'd go see the dr. If kid cried immediately, rubbed head & resumed play at similar intensity, i'd monitor.