[Anatomical study of the yellow ligament of the spine with special reference to its ossification]

In thoracolumbar spine, the interlaminar and the capsular portion of the yellow ligament differed in their location and direction of elastic fibers. However, the capsular portion in most cervical spines were not considered to represent elastic tissues. At the ligament-osseous junction (enthesis) in the thoracolumbar spine, decreased elastic fibers, hyalinized collagen fibers, emergence of fibrocartilaginoid cells and intra-ligamentous calcification were noted. In the cervical spine and in part of the thoracolumbar spin, however, elastic fibers were close to the bony tissue partially penetrating it without the above-mentioned histological findings. Small ossification in the yellow ligament of a cadaver was considered to be "degenerative enthesopathy (enthesophyte)" originating from "enthesis". But in operative cases, the ossification had the same direction and location as those of the small ossification seen in a cadaver, but endogenous factors were strongly suggested because of the extensive change in matrix prior to ossification.