L1 nerve block is a surgical procedure that treats symptoms in the area innervated by the lumbar 1 nerve root through local anesthesia. Nerve block is a type of local anesthesia that is used to anesthetize the nerve trunk or plexus to produce anesthesia in the innervated area, as well as to treat inflammation and give nerve nutrition to help repair damage. Nerve block is also a type of local anesthesia that is helpful in removing superficial skin masses. The area innervated by L1 is located in the inguinal area and lower abdomen, and even affects the raphe reflex. Once this nerve is lesioned, it can cause pain and numbness in the lower abdomen and inguinal area, which can be reduced or eliminated with a nerve block.