GO:0042361:   menaquinone catabolic process
The chemical reactions and pathways resulting in the breakdown of menaquinones, any of the quinone-derived compounds synthesized by intestinal bacteria. Structurally, menaquinones consist of a methylated naphthoquinone ring structure and side chains composed of a variable number of unsaturated isoprenoid residues. Menaquinones have vitamin K activity and are known as vitamin K2.