Well, that's unidiomatic... but technically correct, added.
The vocabulary here is a bit confusing. Technically "ręka" is the hand (from the wrist to the fingertips), but in fact it's used for the whole upper limb as well. And "dłoń" should be the palm of the hand (only the inside), but in fact it's used for the whole hand as well.
And those 'in fact' usages are normal, everyday usages, not something that is 'just possible'.