A dismantlable medical instrument including first, second and third components, a first bayonet connection for releasable mechanical connection of the third and second components, and a second bayonet connection for releasable mechanical connection of the third and first components. In a first predetermined position of the third component relative to the second component, the third component is not connected to the second component. In a second predetermined position of the third component relative to the second component, the third component is mechanically connected to the second component by the first bayonet connection, and the second and third components are not connected to the first component. In a third predetermined position of the third component relative to the second and first components, the third component is mechanically rigidly connected to the second component by the first bayonet connection and to the first component by the second bayonet connection.