A medical apparatus (100) is provided, comprising a closure device (102), which comprises a locking member (130) and a tubular member (121) having a distal set of struts (122) and a proximal set of struts (123), said struts being provided with a hinge section, and an insertion assembly (101), which comprises a holder (106) and an actuator (107), the holder being releasably engaged in the locking member and the actuator being releasably engaged with the tubular member, wherein, in response to a relative movement between the holder and the actuator, the closure device is movable between a first elongated tubular introduction configuration and a second positioning configuration in which the tubular member is compressed such that the distal and proximal sets of struts have moved radially away from a longitudinal central axis of the closure device.