A CROXIO- CLA VICULAR ARTICULA TION. 



343 



Superior Acromio-clavicular. 

 Inferior Acromio-clavicular. 

 Interarticular Fibro-cartilage. 



( Trapezoid 



Coraco-clavicular < and 

 Conoid. 



The Superior Acromio-clavicular Ligament is a broad band, of a quadrilateral 

 form, which covers the superior part of the articulation, extending between the 

 upper part of the outer end of the clavicle and the adjoining part of the upper 

 surface of the acromion. It is composed of parallel fibres which interlace with 

 the aponeurosis of the Trapezius and Deltoid muscles ; below, it is in contact with 

 the interarticular fibro-cartilage (when it exists) and the synovial membranes. 



The Inferior Acromio-clavicular Ligament, somewhat thinner than the pre- 

 ceding, covers the under part of the articulation, and is attached to the adjoining 

 surfaces of the two bones. It is in relation, above, with the synovial membranes, 

 and in rare cases with the interarticular fibro-cartilage ; below, with the tendon 



FIG. 243. The left shoulder-joint, scapulo-clavicular articulations, and proper ligaments of scapula. 



of the Supraspinatus. These two ligaments are continuous with each other in 

 front and behind, and form a complete capsule round the joint. 



The Interarticular Fibro-cartilage is frequently absent in this articulation. 

 ^ hen it exists it generally only partially separates the articular surfaces, and 

 occupies the upper part of the articulation. More rarely it completely separates 

 the joint into two cavities. 



The Synovial Membrane. There is usually only one synovial membrane in 

 this articulation, but when a complete interarticular fibro-cartilage exists there are 

 two synovial membranes. 



The Coraco-clavicular Ligament serves to connect the clavicle with the coracoid 

 process of the scapula. It does not properly belong to this articulation, but as it 

 forms a most efficient means in retaining- the clavicle in contact with the acromial 



