496 



DISSECTION OF THE THORAX. 



Articular 

 have capsule 

 and synovial 

 sac. 



Motion in 

 the joints. 



extent ; 



attach- 

 ments : 



thickness. 



Ligaments 

 of spines : 



supraspi- 

 nous : 



and inter- 

 spinous. 



Inter- 



transverse 



ligaments. 



Joints of articular processes. Between the articulating processes 

 there is a moveable joint, in which the bones are covered with 

 cartilage, and are surrounded by a capsular ligament, enclosing a 

 synovial membrane. The capsules are loosest in the cervical, and 

 strongest in the lumbar region. 



Movement. In these gliding joints the articular processes of the 

 vertebrae move to a limited extent over one another, the direction 

 of the motion being determined by the form and inclination of their 

 surfaces. The kinds of movement permitted in any portion of the 

 column are thus dependent npon the characters of the joints between 

 the articular processes. The movements are freest in the cervical 



region, and least extensive between 

 the upper dorsal vertebrae. By their 

 overlapping, the articular processes 

 also help in giving security to the 

 spine ; and in dislocation of the 

 vertebrae they are generally broken 

 off. 



Ligaments of the arches. The liga- 

 menta subflava (fig. 183) are small 

 rhomboidal sheets of yellow elastic 

 tissue, which close the intervals 

 between the neural arches at the 

 back of the spinal canal from the 

 axis to the sacrum. In each interval 

 there are two ligaments, a right and 

 a left, which meet in the middle line, 

 and extend from the root of the 

 spine to the articular processes. 

 They are attached above to the 

 anterior or deep surface of the 

 laminae of one vertebra, and below 

 to the upper border and posterior 

 surface of the laminae of the next. 

 They are thin in the neck, and strongest in the loins. 



Ligaments of the spines. Along the tips of the spinous processes 

 of the dorsal and lumbar vertebrae is a longitudinal band of fibres 

 (fig. 184, x ) the supraspinous ligament. It is thickest in the 

 lumbar region and consists of superficial fibres which pass over 

 three or more spines, and deep fibres which unite adjoining bones. 

 Many of the back muscles arise from it on each side. 



In the same regions, there are also membranous interspinous 

 ligaments (fig. 177, 5 ) reaching from the root to the tip of the 

 spinous processes. They are thicker and broader in the lumbar 

 than in the dorsal part of the column. 



In the neck the place of the supraspinous and interspinous 

 ligaments is taken by the ligamentum nuchae (p. 6). 



Ligaments of the transverse processes. In the loins the inter- 

 transverse ligaments are thin membranous bands in the intervals 

 between the processes. In the dorsal region there are rounded 



FIG. 183. AN INNER VIEW OP 

 THE NEURAL ARCHES OP THE 

 VERTEBRJE, WITH THEIR INTER- 

 POSED LIGAMENTS (BOURGERY). 



1 and 2. Ligamenta subflava. 



