ARTICULATIONS OF THE SPINE. 



133 



Fig. 80. 



becoming confounded with the interspinous ligaments of the neck. The 

 fibres of the two last digitations are few in number, widely separated from 

 one another, and united by many anastomosing brandies, which make them 

 appear as a kind of wide network. The laminae of the cervical ligament are 

 in relation, outwardly, with the superior branch of the ilio-spinal ligament, 

 the transverse spinous muscle of the neck, and the great complexus. 



(This important structure, which is in reality the mechanical stay and 

 support of the heavy head and neck of quadrupeds, and is usually termed the 

 ligamentum nuchce, is all but absent in Man, being represented in him by a thin 

 narrow baud, or rather two thin planes of fibres, the ligamenta subflava. It is 

 described by Leyh as if there were not two portions, and that excellent 

 anatomist does not appear to insist sufficiently on the difference between the 

 dorso-nuchal and the dorso-lumbar divisions. Percivall, who almost entirely 

 neglects the ligaments, also makes no distinction. The difference in structure, 

 elasticity, and situation, warrants the distinction made by Chauveau. As 

 already indicated, the function of this ligament, and more particularly of its 

 nuchal division, is to maintain the head and neck in their natural position 

 during repose, and to allow the most extensive movements at other 

 times. ) 



b. Interspinous ligaments (Fig. 80, 3). Fibrous laminae fill the inter- 

 spinous spaces, and are attached, before and behind, to the opposite borders 

 of the spinous processes which they unite ; they 



are continued below by the interlamellar liga- 

 ments, forming two lateral planes which are 

 applied against each other, like the laminae of the 

 cervical ligament, and covered outwardly by the 

 transverse spinous (dorsalis colli) muscle. 



In the region of the neck, the interspinous 

 ligaments are yellow and elastic. In the dorso- 

 lumbar region, they are formed by fasciculi of 

 white fibrous tissue, loosely united to each other 

 at their extremities, and directed very obliquely 

 backwards and downwards. In consequence of 

 this disposition, and notwithstanding their in- 

 extensibility, they permit the separation of the 

 spinous processes. Their lateral surfaces are 

 divided by a layer of grey elastic fibres, which 

 cross like an X the direction of the preceding 

 fasciculi. Very abundant in the anterior moiety 

 of the dorsal region, these fibres operate, by their 

 proper elasticity, in bringing the spinous pro- 

 cesses towards each other. 



c. Interlamellar, or interannular ligaments. 

 Situated, as their name indicates, between the 

 vertebral laminae, and divided into two lateral 

 moieties, these ligaments appear to be produced 



by the two fibrous planes of the preceding ligaments, which, on arriving 

 at the base of the spinous processes, separate from one another to be carried 

 outwards. Their anterior border is inserted into the posterior margin of the 

 vertebral lamina in front. Their posterior border is fixed to the anterior 

 border and inferior face of the lamina behind. Their superior face is in 

 relation with some spinal muscles, and their inferior face is in contact with 

 ; the dura mater. Outwardly, they are confounded with the capsules proper 

 12 



a' 



INTERVERTEBRAL ARTICULA- 

 TIONS. 



A, B, C, Bodies of three dorsal 

 yertebrae divided longitudi- 

 nally and vertically to show 

 (1, 1) a section of the in- 

 tervertebral discs ; 2, Super- 

 spinous dorso-lumbar liga- 

 ment ; 3, Interspinous liga- 

 ment ; 4, Fibrous fascia, con- 

 stituting the proper capsule 

 to the articular processes 

 in the dorsal region. 



