a selectively lockable introducer assembly is disclosed that comprises an introducer cannula and a needle guide . the introducer cannula is defined by a proximal end and a distal end and includes a lumen extending therebetween . the needle guide is defined by a body portion that includes at least one channel extending therethrough . the introducer cannula is configured to be selectively receivable within the at least one channel and the introducer cannula may be selectively lockable with respect to the needle guide such that the introducer cannula is selectively prevented from moving laterally with respect to the needle guide .