How To Do an Ulnar Nerve Block By Richard Pescatore, DO, Delaware Division of Public Health Reviewed / Revised Oct 2021 | Modified Sep 2022 View Patient Education Indications Contraindications Complications Equipment Additional Considerations Relevant Anatomy Positioning Step-by-Step Description of Procedure Aftercare Warnings and Common Errors Tricks and Tips Topic Resources How To Do an Ulnar Nerve Block An ulnar nerve block anesthetizes both the volar and dorsal surfaces of the hypothenar half of the hand (from the little finger through the ulnar half of the ring finger).