A connection apparatus for a medical device comprising: a first connection member having a first end and a second end , the first connection member having a shoulder adjacent to the first end of the first connection member and defining at least one channel adjacent the first end , the shoulder is rounded and defines a channel entry , the at least one channel having a first portion extending in an axial direction, the first connection member having a longitudinal axis, and a second portion extending in a transverse direction relative to the axial direction; and a second connection member having a first end and a second end , the second connection member having at least one protrusion adjacent the first end , the second connection member having a longitudinal axis, wherein when the at least one protrusion of the second connection member enters the at least one channel of the first connection member , axial movement of the second connection member towards the first connection member causes at least one of the first and second connection members to rotate relative to the other connection member to enter a locked state in which the protrusion is engaged within the second portion of the channel to secure the first connection member to the second connection member , characterized in that when the longitudinal axes of the first and second connection members (10; 70) are substantially aligned, the shoulder is configured to guide the at least one protrusion of the second connection member into the channel entry , regardless of the orientation of the at least one protrusion relative to the channel entry prior to the entrance of the protrusion into the channel entry . a first connection member having a first end and a second end , the first connection member having a shoulder adjacent to the first end of the first connection member and defining at least one channel adjacent the first end , the shoulder is rounded and defines a channel entry , the at least one channel having a first portion extending in an axial direction, the first connection member having a longitudinal axis, and a second portion extending in a transverse direction relative to the axial direction; and a second connection member having a first end and a second end , the second connection member having at least one protrusion adjacent the first end , the second connection member having a longitudinal axis, wherein when the at least one protrusion of the second connection member enters the at least one channel of the first connection member , axial movement of the second connection member towards the first connection member causes at least one of the first and second connection members to rotate relative to the other connection member to enter a locked state in which the protrusion is engaged within the second portion of the channel to secure the first connection member to the second connection member , characterized in that when the longitudinal axes of the first and second connection members (10; 70) are substantially aligned, the shoulder is configured to guide the at least one protrusion of the second connection member into the channel entry , regardless of the orientation of the at least one protrusion relative to the channel entry prior to the entrance of the protrusion into the channel entry . <EOS>