228 



THE ARTICULATIONS 



ward over an intervertebral fibro-cartilage, and reach the narrow portion of the ligament on the 

 centre of the vertebra next below; thej^ then diverge to pass over another intervertebral dies 

 to end on the body of the vertebra bej-ond, near the intervertebral notch. They thus pass 

 over two discs and thi'ee vertebrse. Deeper still are other fibres thickening these expansions 

 of the longitudinal hgament, and extending from one bone to the next. 



The last weU-marked expansion is situated between the first two segments of the sacrum: 

 below this, the hgament becomes a deUcate central band with rudimentary expansions, being 

 more pronounced again over the sacro-coccj'geal joint, and losing itself in the ligamentous 

 tissue at the back of the coccyx. The dura mater is tightly attached to it at the margin of the 

 foramen magnum and behind the bodies of the upper cervical vertebrse, but is separated from 

 it in the rest of its extent by loose cellular tissue which becomes condensed in the sacral region 

 to form the sacro-dural ligament. The filum terminale becomes blended with it at the lower 

 part of the sacrum and back of the coccyx. 



Fig. 267. — Posterior Longitudinal Ligament. (Lumbar region.) 



Median band 

 Expanded lateral portion 



The lateral (or short) vertebral ligaments (fig. 265) consist of numerous short 

 fibres situated between the anterior and posterior longitudinal ligaments, and 

 passing from one vertebra over the intervertebral disc, to which it is firmly- 

 adherent, to the next vertebra below. 



The more superficial fibres are more or less vertical, but the deeper decussate and have a 

 crucial arrangement. They are connected with the deep surface of the anterior longitudinal 

 ligament, and so tie it to the edges of the l)odies of the vertebrae and to the intervertebral discs. 

 They blend behind with the expansions of the posterior longitudinal ligament, and so complete 

 the casing roiind each amphiarthrodial joint. In the thoracic region, they overlie the radiate 

 ligament, and in the lumbar they radiate toward the transverse processes. In the cervical 

 region they are less well marked. 



{h) The Ligaments Connecting the Articular Processes 



Class. — Diarthrosis. Subdivision. — Arthrodia. 



The articular capsules (fig. 259) which unite these processes are composed 

 partly of yellow clastic tissue and partly of white fibrous tissue. In the cervical 

 region only the medial side of the capsule is formed by the ligamenta flava, which 

 in the thoracic and lumbar regions, however, extend anteriorly to the margins 

 of the intervertebral foramina. 



The part formed of white fibrous tissue consists of short, well-marked fibres, which in the 

 cervical region pas.s obliquely downward and forward over the joint, between the articular proc- 



