148 ARTICULATIONS OF THE LTrER LIMB. 



inserted into the clavicle. In the angle between the conoid and trapezoid 

 ligaments there is frequently present a synovial bursa. 



Movements. — The movements allowed at the clavicular articulations are 

 limited, not yo much by the foiins of the articular surfaces, as by the costo- 

 clavicular and coraco-cla-^-icular ligaments, and the position of the thoracic wall. 

 When the clavicle is forcibly depressed, as in liftuig a. heavy weight, it presses 

 upon the first rib, its sternal end rises, and the interarticular cartilage and inter- 

 clavicular ligament are put upon the stretch. When the shoulders are tl^a^\^l 

 backwards and do^vnwards the angle between the clavicle and the upper border 

 of the scapula is increased by the descent of the scapular arch on the conical 

 wall of the thorax. In raising and depressmg the arm to its full extent, there 

 is not only vertical movement at the shoulder joint, but also movement at the 

 stemo-clavicular and acromio-clavicular articulations. 



Ligaments of the Scapula. — There are two ligaments which 

 stretch fi'om one part of the scapula to another, I. The coracoid or 

 suprascapular ligament is a thin, flat band of fibres, attached by 

 its extremities to the opposite margins of the notch at the root of the 

 coracoid process, which it thus converts into a foramen for the trans- 

 mission of the supra-scapular nerve, the corresponding artery most 

 commonly passing above it. This ligament is fi-equently converted into 

 bone. 2. The coraco-acromial ligament, broad, firm, and triangular, 

 is attached by its broader extremity to the outer edge of the coracoid 

 process, and by the narrower to the tip of the acromion. Its inferior 

 surface looks downwards upon the shoulder joint, the superior is covered 

 by the deltoid muscle. It completes the arch formed by the coracoid 

 and acromion processes, and gives protection to the shoulder joint. 



THE SHOULDER JOINT. 



In this articulation the large and hemispherical head of the humerus 

 is opposed to the much smaller surface of the glenoid cavity of the 

 scapula. The bones are retained in position, not by the direct tension 

 of ligaments, which would restrict too much the movements of the joint, 

 but by surrounding muscles and atmospheric pressure. 



Fig. 134. Fig. 134. — View of the Glenoid Cavity and Liga- 



ments BETWEEN the ScAPULA AND ClAVICLE OF 

 THE RIGHT SIDE. 3 



1, glenoid fossa, its cartilaginous surface ; 2, the 

 glenoid ligament or fibrous border ; 3, the tendon of 

 the biceps muscle seen in connection with the u^jper 

 part of the glenoid fossa and ligament ; 4, ujiper sur- 

 face of the coracoid process ; 5 and (>, on the adjacent 

 part of the clavicle ; 4 to 5, the conoid ; 4 to (J, the 

 trapezoid portion of the coraco-clavicular ligiDiient ;. 7, 

 the apex of the acromion ^jrocess ; 4 to 7, the coraco- 

 acromial ligament ; 8, the acromio-clavicular articu- 

 lation, whicli is represented as open anteriorly, show- 

 ing a wedge-shaped interarticular cartilage attached 

 above to the superior acromio-clavicular ligament ; 

 X , the inferior acromio-clavicular ligament. 



The capsular ligament is attached to the scapula round the 

 jnargin of the glenoid cavity, and to the humerus at the place where 

 the neck springs from the tuberosities and shaft. It extends furthest 



