Injection needle assembly comprising:• at least N injection needles where N is at least four and a multiple of two,• a first liquid port adapted to be connected to an injection device,• N second liquid ports, each connected to one of the N injection needles,• N2 main liquid pathways each having an entrance connected to the first liquid port and an exit,wherein it further comprises N2 secondary liquid pathways comprising:• two extremities each opening on one of the N second liquid ports, and• a mid portion connected to the exit of one of the main liquid pathways；and wherein the main liquid pathways and the secondary liquid pathways define N liquid flow paths between the first liquid port and the N second liquid ports and are dimensioned so that a pressure drop between the first liquid port and each of the N second liquid ports is similar.
