174 SURGICAL APPLIED ANATOMY. [Chap. XL 



and in a less direct manner by the two remaining 

 ligaments of the joint. Thus it happens that dis- 

 location upwards is the least common of the luxations 

 at this articulation. 



Disease of the sterno-clavicular joint. 

 This articulation is really divided into two joints by 

 the interarticular cartilage, each being provided with 

 a distinct synovial membrane. 



These joints are liable to the ordinary maladies 

 of joints, and it would appear that the disease may 

 commence in, and be for some time limited to, one only 

 of the synovial sacs. In time the whole articulation 

 usually becomes involved, but even in advanced cases 

 the mischief is sometimes restricted to the synovial 

 cavity on one side of the cartilage. According to 

 some authors, this joint is more frequently involved 

 in pyaemia than is any other. When effusion has taken 

 place into the sterno-clavicular joint, and especially 

 after suppuration has ensued, the swelling usually 

 makes itself evident in front, owing to the fact that 

 the anterior sterno-clavicular ligament is the thinnest 

 and least resisting of the ligamentous structures about 

 the articulation. For the same reason the pus usually 

 escapes from the anterior surface, when it discharges 

 itself spontaneously. It may, however, make an 

 opening for escape through the posterior ligament, 

 and under these circumstances has found its way into 

 the mediastinum. The relations of this joint to the 

 great vessels at the root of the neck should be borne 

 in mind. In one case reported by Hilton a large 

 abscess formed in the articulation, and the collection, 

 receiving pulsations from the subjacent artery (the 

 innominate or right subclavian), was supposed at one 

 time to be an aneurism. It is remarkable that disease 

 of this joint never leads to anchylosis. This cir- 

 cumstance may be explained (1) by the constant 

 slight movement in the part which prevents the 



