The present disclosure concerns a system (4) for holding a medical instrument (21； 22) comprising a male member (41) comprising at least one male thread (416) and at least one first axial lumen (411) and a female member (42) comprising at least one female thread (426) and at least one second axial lumen (421) When the at least one male thread (416) and the at least one female thread (426) are engaged to each other, the at least one first axial lumen (411) and the at least one second axial lumen (421) form a common axial lumen (411, 421) for at least partially receiving a medical instrument (21； 22). The system (4) further comprises a locking means (412, 427) for locking the medical instrument (21； 22) in the common axial lumen (411, 421) at a predetermined position.
