A medical instrument that includes a needle and an expandable member located at a distal end of the needle. The expandable member includes a blocking member. The expandable member is configured to move tissue away from a distal end of the needle and/or from a distal end of a tubular member that is in fluid communication with a substance source. A substance is configured to be expelled into the anatomy through the expandable member. The blocking member is configured to restrict or prevent the substance from being expelled through the portion of the expandable member that includes the blocking member.