Nerve block

The injection of a local anaesthetic around a nerve to produce loss of sensation in a part of the body supplied by that nerve. For example, the palm of the hand may be anaesthetized by giving injections at sites up the arm, blocking the ulnar and median nerves. A nerve may be blocked as it leaves the spinal cord. This occurs in epidural anaesthesia, used mainly in childbirth, and in spinal anaesthesia, used mainly for surgery of the lower abdomen and limbs. In a caudal block an anaesthetic is injected around nerves leaving the lowest part of the spinal cord. It produces anaesthesia in the buttock and genital areas, and is occasionally used in childbirth. A pudendal nerve block involves the injection of an anaesthetic into nerves passing under the pelvis into the floor of the vagina. This type of nerve block is sometimes used in a forceps delivery. (See also anaesthesia, local.)