1st was Melendez
4th was Henderson
Points could be made for either fighter for the other rounds.
Henderson did just enough to probably steal the 2nd round, in rounds that close the fighter that takes the second half of it usually gets the nod as judges almost never give 10-10 rounds.
3rd round was probably Hendersons as well, final knockdown in the round helped tip it his way.
5th round was very close as well with Henderson winning for the first half but then Melendez picking it up and like the 2nd round probably stealing it based on looking best at the end of the round.
Either way you can't really complain about the decision, the fight was just too close to really call and it comes down to personal choice. At least all the judges got it right with 48-47 scores and a split decision. Melendez will likely get a rematch soon though as this fight definitely could have went his way and we all know how the UFC likes rematches in close title fights.