|Henry Gray (18251861). Anatomy of the Human Body. 1918.|
|thicker in the thoracic than in the cervical and lumbar regions, and somewhat thicker opposite the bodies of the vertebræ than opposite the intervertebral fibrocartilages. It is attached, above, to the body of the axis, where it is continuous with the anterior atlantoaxial ligament, and extends down as far as the upper part of the front of the sacrum. It consists of dense longitudinal fibers, which are intimately adherent to the intervertebral fibrocartilages and the prominent margins of the vertebræ, but not to the middle parts of the bodies. In the latter situation the ligament is thick and serves to fill up the concavities on the anterior surfaces, and to make the front of the vertebral column more even. It is composed of several layers of fibers, which vary in length, but are closely interlaced with each other. The most superficial fibers are the longest and extend between four or five vertebræ. A second, subjacent set extends between two or three vertebræ while a third set, the shortest and deepest, reaches from one vertebra to the next. At the sides of the bodies the ligament consists of a few short fibers which pass from one vertebra to the next, separated from the concavities of the vertebral bodies by oval apertures for the passage of vessels.|
FIG. 301 Median sagittal section of two lumbar vertebræ and their ligaments. (See enlarged image)
The Posterior Longitudinal Ligament (ligamentum longitudinale posterius; posterior common ligament) (Figs. 301, 302).The posterior longitudinal ligament is situated within the vertebral canal, and extends along the posterior surfaces of the bodies of the vertebræ, from the body of the axis, where it is continuous with the membrana tectoria, to the sacrum. It is broader above than below, and thicker in the thoracic than in the cervical and lumbar regions. In the situation of the intervertebral fibrocartilages and contiguous margins of the vertebræ, where the ligament is more intimately adherent, it is broad, and in the thoracic and lumbar regions presents a series of dentations with intervening concave margins; but it is narrow and thick over the centers of the bodies, from which it is separated by the basivertebral veins. This ligament is composed of smooth, shining, longitudinal fibers, denser and more compact than those of the anterior ligament, and consists of superficial layers occupying the interval between three or four vertebræ, and deeper layers which extend between adjacent vertebræ.