Ropivacaine is a newer local anesthetic which is structurally related to bupivacaine, but has fewer side effects. It is more cardio stable than bupivacaine, but the onset of action is delayed and the duration of action is shorter than bupivacaine making its use during regional anesthesia less preferable to many anesthesiologists. Steroids like dexamethasone, or alpha-2 agonists like dexmedetomidine are being studied as adjuvants to ropivacaine for brachial plexus block to improve its anesthetic properties and have shown favorable outcome in terms of shortening the onset of block and prolonging the duration of action. But no study has been done to compare their effects. So in this study the investigators want to compare the effectiveness of dexamethasone and dexmedetomidine as an adjuvant to 0.5% ropivacaine for supraclavicular brachial plexus block on the onset of block and duration of analgesia, so that the investigators can choose the better adjuvant for the investigators routine practice of regional anesthesia.