Zygapophyseal joints are formed between the inferior articular facets of one vertebra and the superior articular facets of its subjacent vetebra, not surprisingly these joints are usually known as facet joints.
Facet joints have a dual nerve supply from the spinal nerves that emerge above and below the joints.
The facet joint between L5 and the sacrum is important in helping to fix the nonfused part of the vertebral column onto the sacrum. Ligamentum flava joins laminae of adjacent vertebra. Supraspinatus ligament is a strong white fibrous cord that join the apex of adjacent spinous processes from C7 to the sacrum. Interspinous ligaments are weak sheets of fibrous tissue joining spinous processes, they are well developed in the lumbar region. In the neck the supraspinatus and interspinous ligaments are replaced by the ligamentum nuchae .