276 



ARTICULATIONS. 



The Anterior Costo-vertebral or Stellate Ligament connects the anterior part ot 

 the head of each rib with the sides of the bodies of two vertebras, and the in- 

 ter vertebral disk between them. It consists of three flat bundles of ligamen- 



tous fibres, which radiate 



Fig. 191.-Costo-vertebral and Costo-transverse Articulations. frQm the anterior t 

 Anterior View. , . , . * 



of the head of the rib. 



The superior fasciculus 

 passes upwards to be 

 connected with the body 

 of the vertebra above ; 

 the inferior one descends 

 to the body of the ver- 

 tebra below ; and the 

 middle one, the smallest 

 and least distinct, passes 

 horizontally inwards to 

 be attached to the inter- 

 vertebral substance. 



Relations. In front, 

 with the thoracic gan- 

 glia of the sympathetic, 

 the pleura, and, on the 

 right side, with the vena 

 azygos major; behind, 

 with the interarticular 

 ligament and synovial 

 membranes. 



In the first rib, which 

 articulates with a single vertebra only, this ligament does not present a distinct 

 division into three fasciculi; its superior fibres, however, pass to be attached 

 to the body of the last cervical vertebra, as well as to the body of the vertebra 

 with which the rib articulates. In the eleventh and twelfth ribs also, which 

 likewise articulate with a single vertebra, the division does not exist ; but the 

 upper fibres of the ligament, in each case, are connected with the vertebra 

 above, as well as that with which the ribs articulate. 



The Capsular Ligament is a thin and loose ligamentous bag, which surrounds 

 the joint between the head of the rib and the articular cavity formed by the 

 junction of the vertebrae. It is very thin, firmly connected with the anterior 

 ligament, and most distinct at the upper and lower parts of the articulation. 



The Interarticular Ligament is situated in the interior of the joint. It con- 

 sists of a short band of fibres, flattened from above downwards, attached by one 

 extremity to the sharp crest on the head of the rib, and by the other to the 

 intervertebral disk. It divides the joint into two cavities, which have no com- 

 munication with one another, but are each lined by a separate synovial mem- 

 brane. In the first, eleventh, and twelfth ribs, the interarticular ligament does 

 not exist ; consequently, there is but one synovial membrane. 



Actions. The movements permitted in these articulations are limited to 

 elevation, depression, and a slight amount of movement forwards and back- 

 wards. The mobility, however, of the different ribs varies very much. The 

 first rib is almost immovable, excepting in deep inspiration. The movement 

 of the second rib is also not very extensive. In the other ribs, their mobility 

 increases successively to the last two, which are very movable. The ribs are 

 generally more movable in the female than in the male. 



JLmver Synovial cavil 'a 



