One of a series of bands of elastic tissue that runs between the lamina from the axis to the sacrum, the ligamentum flavum connects the laminae and fuses with the facet joint capsules. These bands serve as a covering over the spinal canal.
Ligamentum flavum literally means "yellow ligament," and is so known because it has a yellow coloring due to the amount of elastin (a springy type of collagen). The elastin pulls the ligament out of the canal when the spine is extended. As we age, the ligament loses elastin, and this allows the ligament to encroach on the canal.
The ligament can become a substantial contributor to spinal stenosis, and is usually removed during a lumbar decompression surgery.