What is the function of the chordae tendinae and papillary muscles?

Structure o valve. The valve leaflets are tethered by the chordae tendinae and the papilary muscles. The contraction of the papilary muscles then in turn cause movement of teh valve leaflets allowing opening.
See earlier. Please see my earlier answer to the same question. The papillary muscles are part of the apparatus of the valve, they connect the chordae to the ventricle and support the valve and the ventricle.