154 



THE ARTICULATIONS OF THE TRUNK AND HEAD. 



dorsal region, largest and strongest in the loins, where a band of nearly horizontal 

 fibres extends on each side from the fore part of the upper border of one spine to 

 the hindmost part of the lower border of the spine above. 



The supraspinous ligament consists of bundles of longitudinal fibres, which 

 connect the summits of the spinous processes, and form a continuous cord from the 

 seventh cervical vertebra to the sacrum. The superficial fibres pass down from a 

 given vertebra to the third or fourth below it ; those more deeply seated reach only 

 from one to the next, or the second below it. 



The ligamentum iiuchae replaces the supraspinous and interspinous ligaments 

 in the neck. Its superficial part, which forms a continuation of the supraspinous 



Fig. 178. SAGITTAL SECTION OF THE UPPER PART OP THE 



VERTEBRAL COLUMN, AND PART OF THE OCCIPITAL BONK, 



SHOWING THE ARTICULATIONS. (Allen Thomson, after 

 Arnold.) 



1, 1, anterior common ligament ; 1', anterior occipito- 

 atlantal ligament ; 2, from this figure upwards the posterior 

 common ligament ; 2', the continuation of the preceding or 

 posterior occipito-axial ligament lying on the basilar process of 

 the occipital bone ; 3, 3, 3, these figures are placed on the 

 inside of the arches of the 2nd cervical and 1st and Oth dorsal 

 vertebrae ; the ligamenta subflava are seen stretching between 

 the laminae ; 4, 4, placed upon two of the interspinous liga- 

 ments ; 4', divided edge of the occipital bone behind the 

 foramen magnum, and below it, the posterior occipito-atlantal 

 ligament ; 5, 5, supraspinous ligament ; 6, ligamentum nuchse ; 



x , its upper extremity at the external occipital protuberance ; 



xx, its lower extremity terminating in the supraspinous 

 ligament. 



ligament, is thick and extends from the spine of 

 the seventh cervical vertebra to the external occi- 

 pital protuberance. From this a thin median 

 septum is continued forwards to the external occi- 

 pital crest and the spines of the upper vertebrae, as 

 well as into the intervals between the latter. The 

 ligament consists in man mainly of white fibrous 

 tissue ; but in the lower animals it is a strong 

 elastic structure which supports the head. 



The supra- and interspinous ligaments, together 

 with the ligamentum nuchae, are derived from the 



median dorsal intermuscular septum. In the lumbar region the spinous processes of adjacent 

 vertebrae sometimes become united by synovial articulations near their free extremities. 



The intertransverse ligaments are unimportant bands extending between the 

 transverse processes. In the lumbar region they are membranous and correspond to 

 the anterior superior costo-transverse ligaments of the ribs ; in the mid-dorsal 

 region there are small rounded bundles taking the place of the intertransverse 

 muscles of the lower spaces ; and in the upper dorsal and cervical regions they are 

 generally wanting. 



Movements. The movements of flexion and extension of the vertebral column are freely 

 allowed in the cervical and lumbar regions, but in the dorsal are limited by the small amount 

 of intervertebral substance and the imbrication of the laminae. The greatest bending back- 

 wards is permitted in the cervical, the greatest bending forwards in the lumbar region, 

 especially between the last three vertebras. Movements in other directions are determined 

 chiefly by the articular processes. In the dorsal region the articular surfaces of each vertebra 

 lie in the arc of a circle the centre of which, is in front, between the bodies of the vertebrae. 



