<prompt> Prolapsed interveebral Disc is most common at-C10C11C2C3L2L4L5S1  <response>: L5-S1 disc space is the most commonly involved space in disc prolapse. Lumbar interveebral disc herniation is most common at L5-S1 and slightly less common at L4 - L5, and rare at L3-L4 or above. The disc at L5-S1 is most commonly involved, followed in order by L4-L5 and L3-L4. REF : MAHESWARI 9TH ED 