The present teachings relate generally to a medical flexible needle assembly (10), comprising a needle portion (20) disposed at a distal end (12) of the assembly; a stiff portion (30) disposed at a proximal end 14 of the assembly; an flexible portion disposed between and interconnecting the needle portion and the stiff portion, including a flex distal portion (42), a flex proximal portion (44); and a jacketing member (50) disposed about the assembly (10) over at least part of the flexible portion (40); characterized in that the jacketing member (50) includes one or more coupled regions (60) and one or more decoupled region (70), wherein in at least one or more of the one or more coupled regions (60) are located proximally, distally, or both of the flexible portion (40).