This is a nerve block used to numb an area for surgery. It's used most often for operations to the shoulder, arm, and hand. Interscalene brachial plexus describes which nerve and its location.

A needle is inserted into the skin around the sixth neck vertebrae on the same side as the involved shoulder. The doctor makes sure the needle is in the right place and begins to slowly and carefully inject a local numbing agent into the area.

Usually operations on the upper arm and hand are done under general anesthesia with the patient fully asleep. The cost and problems with this method have resulted in the use of regional anesthesia. There's an added benefit, too. Pain after the operation is much less with a local block.