246 ARTICULATIONS OF THE SHOULDER. 



with the apparatus of a movable articulation. They are 

 covered with cartilage, and are invested with a small synovial 

 capsule. The upper and lower surfaces of the extremities of 

 the clavicle and acromion are covered by a ligamentous mem- 

 brane, which is called, from its situation, the superior and infe- 

 rior ligament of this articulation. 



Coraco-clavicular, consisting of two portions, conoid and trape- 

 zoid. But these bones are more firmly connected by the liga- 

 ment which passes to the coracoid process of the scapula from 

 the under side of the clavicle, and is very strong. ISome of tne 

 fibres which compose this ligament are so arranged that they 

 have the appearance of an inverted cone : the remaining fibres 

 appear like another ligament, and therefore they have been 

 called the trapezoid and conoid ligaments. 



The base of the conoid ligament is upwards, and its apex 

 or origin is at the root of the coracoid process. It is the stronger 

 of the two. The trapezoid is at the outer side of the conoid. 

 It is broad and thin, with its fibres separated by interstices. It 

 rises from the root of the coracoid process, 'and is inserted on an 

 oblique ridge, leading from the tubercle of the clavicle to its 

 acromial end. 



By their situation and strength they are enabled to retain the 

 bones in their proper relative positions, at the same time that 

 they permit a peculiar rotary motion. 



There is a bifid ligament called Kgamentum bicorne, arising 

 from the root of the coracoid process, at the inner side of the 

 conoid, which runs inwards in front of the subclavius muscle, 

 to which it serves as a fascia, and bifurcates ; one horn is 

 attached to the under surface of the clavicle near the rhomboid 

 ligament, and the other to the end of the first rib, under the 

 tendon of the subclavius muscle. 



^Articulation of the Os Humeri and Scapula, (Scapulo-humeral.) 



The spherical portion of the upper extremity of the os humeri 

 is the part of that bone which is principally concerned in the 

 articulation, and is covered with cartilage ; as is also the glenoid 

 -cavity of the scapula. 



