136 ARTICULATIONS OF THE UPPER LIMB. 



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 so much by the forms of the articular surfaces, as by the costo-clavicular and coraco- 

 clavicular ligaments, and the position of the thoracic wall. When the clavicle is 

 forcibly depressed, as in lifting a heavy weight, it presses upon the first rib, 

 the upper border of its inner end rises above the sternum, and the interarticular 

 cartilage and interclavicular ligament are put upon the stretch. When the 

 shoulders are drawn backwards and downwards, 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 depressing the arm to its full extent, there 

 is not only vertical motion at the shoulder joint, but also motion at the sterno-clavi- 

 cular and acromio-clavicular articulations. 



LIGAMENTS OF THE SCAPULA. There are two ligaments which stretch from 

 one part of the scapula to another. 1. The coracoid or suprascapular ligament 

 (liganienturn proprium posterius), 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 cou verts into a foramen for the transmission of the 

 supra- scapular nerve, the corresponding artery most commonly passing above 

 it. 2. The coraco-acromial ligament (ligamentum proprium anterius), 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. 



THE SHOULDER-JOINT. 



In this articulation the large and hemispherical head of the humerus ia 

 opposed to the much smaller surface of the glenoid cavity of the scapula. 

 The bones are retained ID position, not by the direct tension of strong liga- 

 ments, which would have restricted too much the movements of the joint, 

 but by surrounding muscles and atmospheric pressure. 



The capsular ligament is attached to the scapula round the margin of the 

 glenoid cavity, and to the humerus at the place where the neck springs from 

 the tuberosities and shaft. It extends furthest down the humerus on the 

 internal or inferior aspect, and is strongest on the superior aspect. The laxity 

 of the capsule is such that the humerus drops away from the glenoid cavity 



-__ Fig. 125. VIEW OF THE GLENOID CAVITY AND LIGA- 



MENTS BETWEEN THE SCAIULA AND CLAVICLE OF 1 

 THE RIGHT SIDE. ^ 



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 upper 

 part of the glenoid fossa and ligament; 4, is placed 

 on the upper surface of the coracoid process ; 5 and 6, 

 on the adjacent part of the clavicle ; 4 to 5, the conoid ; 

 4 to 6, the trapezoid portion of the coraco-clavicular 

 ligament; 7, is placed on the apex of the acromion 

 process ; 4 to 7, the coraco-acromial ligament ; 8, is 

 above the acromio-clavicular articulation, which is 

 represented as open anteriorly, showing a wedge- 

 shaped interarticular cartilage attached above to the 

 superior acromio-clavicular ligament; x, the inferior 

 acromio-clavicular ligament. 



as soon as its muscular connections are detached. Superiorly and posteriorly 

 the capsule is strengthened by the tendons of the supraspinatus, infraspiuatus, 



