DISSECTING MANUAL. 



which is thinnest at the centre and sometimes perforated, 

 divides the joint into two cavities. The cartilage adheres to 

 the capsule; it is fixed to the first costal cartilage by its 

 lower margin, and to the apex of the clavicular facet by its 

 upper margin. There are two synovial membranes for the two 

 cavities. [273] 



The capsule is thin below but thick elsewhere. It presents 

 the following thickenings, or proper ligaments, viz.: Anterior 

 sterno-clavicular ; short fibres running from the front of the 

 sternal end of the clavicle, downward and inward to the front 

 of the sternum and anterior border of the first costal cartilage. 

 Posterior sterno-clavicular; similar but weaker fibres on the 

 posterior surface. [273] 



Accessory Ligaments. The interclavicular is a broad band 

 running from the apex of the sternal end and the adjacent 

 margins of the facet on one clavicle to those on the other. 

 While crossing the supra-sternal notch it dips down and is 

 partly attached to the sternum. The rhomboid consists of short 

 fibres running from the top of the first costal cartilage, up- 

 ward and outward to the rough impression on the under 

 surface of the sternal end of the clavicle. [274] 



Acromio-clavicular Joint. This is an arthrodial diarthrosis 

 between the acromion process and acromial end of the clav- 

 icle. It has a complete capsule whose upper and lower parts 

 (superior and inferior acromio-clavicular ligaments') are espe- 

 cially strong. A meniscus usually lies obliquely within, and 

 attached by its edges to, the capsule ; it is usually incomplete. 

 A synovial membrane lines the capsule. [274] 



Coraco-clavicular Ligament. This is accessory to the joint 

 and is divisible into two parts, conoid and trapezoid. The 

 conoid ligament is a triangular band attached by its apex to the 

 top of the coracoid process close to the supra-scapular notch, 

 and by its base to the conoid tubercle of the clavicle. The 

 trapezoid ligament is a band attached below to the top of the 

 posterior half of the coracoid process, antero-external to the 



[150] 



