32 ANTHROPOLOGY. 



viele, descends inwards, and is inserted into the fore part of the sternum. 

 The posterior ligament takes a course behind the joint, parallel to the pre- 

 ceding, and adheres to the joint, restin -• upon the sterno-hyoid muscle. 

 These two ligaments {pi. 125^ fig. 8\fig. 9') are so expanded over the joint 

 as to resemble a capsular or orbicular ligament. 



The inferior costo-clavicular or rhomboid ligament {fig. 9 ^) passes from the 

 lower surface of the sternal end of the clavicle downwards, forwards, and 

 inwards, and is inserted into the cartilage of the first rib; it closes the angle 

 •between it and the clavicle. 



The inter-clavicular ligament {fig. 8'\ fig. 9") extends from the posterior 

 surface of one clavicle to the other; its lower border is generally attached 

 to the posterior lip of the sternum. Its office is to connect the clavicles 

 with each other and with the sternum. The inter-articular cartilage {fig. 9^) 

 is nearly circular, very thin, and often perforated in the centre. On each 

 side is a dry synovial membrane. 



2. ScAPULO-CLAVicuLAR ARTICULATION. The oval end of the clavicle 

 is connected with that of the acromion process by a plain arthrodial joint, 

 which is secured by a superior and an inferior acromio-clavicular ligament 

 {fig. 10'). These are attached to the surfaces of each bone, and being 

 united or continuous both before and behind, the joint may be considered 

 as a strong orbicular ligament. The coraco-acromial ligament really consists 

 of two, the conoid {fig. W) and the trapezoid {fig. 10'). The former is pos- 

 terior and the smaller of the two ; and while united posteriorly and exter- 

 nally, anteriorly they are very distinct. 



3. Proper Liga^nients of the Scapula. These are two in number, an 

 anterior and a posterior. The anterior, deltoid, or coraco-acromial ligament 

 {fig. 10*) arises from the coracoid process, passes upwards, and is inserted 

 into the point of the acromial process. The posterior or coracoid ligament 

 arises from the superior costa of the scapula behind the notch, passes for- 

 wards, and is inserted into the base of the coracoid process ; it converts the 

 notch into a foramen. When this ligament is wanting, as is sometimes the 

 case, the notch is completed into a hole by bone. 



4. HuMERO-scAPULAR OR SHOULDER ARTICULATION. This joint is a ball 

 and socket {enarthrodia), with the head of the humerus retained in the 

 glenoid cavity by the capsular, the coraco-humeral or accessory, and the 

 glenoid ligaments, and a synovial membrane. 



The glenoid ligament adheres to the margin of the glenoid cavity, and 

 deepens the socket for the head of the humerus : it is partly continuous 

 with or derived from the long tendon of the biceps muscle. The capsidar 

 ligament {fig. 10') arises around the head of the scapula, and increasing in 

 size, encircles the head of the humerus, and is inserted into its neck and 

 prolonged on the periosteum. It derives great strength from the tendons 

 of the four capsular muscles which cover and are identified with it. The 

 coraco-humeral or accessory ligament extends obliquely downwards and out- 

 wards from the coracoid process to the anterior part of the great tuberosity. 

 The synovial membrane is reflected over the glenoid surface around the 

 glenoid ligament. 

 738 



