JOINTS OF SHOULDER GIRDLE 15 



iinciform in order. Each of the four inner metacarpals supports 

 three phalanges. 



The third metacarpal has a styloid process from its base on 

 the radial side. 



Ossification. The four inner metacarpals have a primary 

 centre for the shafts and bases developed before birth,* and the 

 heads form a secondary epiphysis. The first metacarpal has the 

 head and shaft formed from the primary centre and the base 

 from the secondary centre. 



The Phalanges are fourteen in number, two on the first 

 metacarpal and three each on the other four. The first 

 phalanx is the largest of the three, the terminal ones being 

 much smaller. They are short stout bones articulating with the 

 metacarpals and one another. 



The terminal phalanges have flattened distal extremities to 

 support the nails. 



Ossification. Similar to that of the first metacarpal bone. 



Sterno-Clavieular Joint, between the sternal end of the 

 clavicle and the outer part of the upper edge of the sternum. 

 A gliding joint, so only gliding movements possible. There 

 are no movements round a distinct axis, but movements which 

 depress or raise the scapula will cause the clavicle to move also, 

 in both its joints. 



Ligaments. The joint is surrounded by a capsule attached to 

 the edges of the articular surfaces of the bones, which is 

 strengthened to form anterior and posterior ligaments. In. 

 addition there is a meniscus, or disc of fibro-cartilage, between 

 the two articular surfaces. 



Accessory Ligaments : Inter clavicular } attached to the sternal 

 end of the clavicle and the suprasternal notch. It is continuous 

 with the one of the other side. This ligament prevents the end 

 of the clavicle being raised up too much when the acromial end 

 is depressed as in carrying heavy weights. 



Rhomboid, attached to the under surface of the sternal end of 

 the clavicle and the upper surface of the first costal cartilage ; 

 it limits the movements of the clavicle when the arms are raised 

 over the head. 



The synomal membrane lines the two joint cavities which are 

 separated by the meniscus. 



