ARTICULATIONS OF THE UPPER EXTREMITIES. 283 



CHAPTER VIII. 



OF THE ARTICULATIONS OF THE UPPER EXTREMITIES. 



' i 



Of the Articulations of the Shoulder. 



THESE articulations consist in the junction of the clavicle to 

 the upper part of the sternum, and to the first rib; of the scapula 

 to the clavicle, and of the os humeri to the scapula. . 



1. Of the Sterno-Clamcular Articulation. 



The uneven triangular face of the internal end of the clavicle, 

 and the concavity of the sternum, at its upper corner, form the 

 surfaces which enter into this articulation. The first is much 

 more extensive than the articular surface of the sternum, pro- 

 jects on every side beyond its margins, and is very prominent 

 in case of extreme emaciation. The two surfaces are covered 

 by cartilage, of which that on the clavicle is the thickest, and 

 serves to fill up its inequalities; while the one on the sternum is 

 thin and smooth. 



The joint is invested by a thick fibrous capsule, the anterior 

 portion of which presents a strong fasciculus of fibres, somewhat 

 separated by small interstices. This portion, called by some 

 the radiated ligament, arises from the anterior extremity of the 

 clavicle, and, going downwards and inwards, is inserted into 

 the margin of the articular cavity of the sternum. It is placed 

 just behind the origin of the sterno-cleido mastoid muscle. The 

 capsular ligament is also strengthened on its posterior surface 

 by additional fibres, not so distinct as the preceding, but ob- 

 taining the name of the posterior ligament. 



Of the Inter-Clavicular Ligament, (Lig. Inter-Claviculare.) 

 Closely connected with the capsule of the preceding joint, this 



