since the top hit directly on your head,the force which exerted transmit through the vertebrae as a result even though no direct hurt over vertebrae you feeling crunching sound and caused the injury
to the muscles supporting the vertebrae over the neck area can call as sprain
to then . if no swelling,color change(bruise
) no need to worry you do some vapor fomentation over that area after 2-3 days of rest. by that time you can take some anti inflammatory drugs internally.