150 LIGAMENTS OF THE UPPER EXTREiMITY. 



S 



Anterior sterno-clavicular, 

 Posterior sterno-clavicular, 

 Inter-clavicular, 

 Costo-clavicular (rhomboid), 



Interarticular fibro-cartilage, 



Two synovial membranes. 



The anterior sterno-clavicular ligament is a broad ligamentous layer, 

 extending obliquely downwards and forwards, and covering the anterior 

 aspect of the articulation. This ligament is in relation by its anterior sur 

 face with the integument and with the sternal origin of the sterno-mastoid 

 muscle ; and behind with the interarticular fibro-cartilage and synovial 

 membranes. 



The posterior sterno-clavicular ligament is a broad fasciculus, covering 

 the posterior surface of the articulation. It is in relation by its anterior 

 surface with the interarticular fibro-cartilage and synovial membranes, and 

 behind with the sterno-hyoid muscle. 



The two ligaments are continuous at the upper and lower part of the 

 articulation, so as to form a complete capsule around the joint. 



The interclavicular ligament is a cord-like band which crosses from the 

 extremity of one clavicle to the other, and is closely connected with the 

 upper border of the sternum. It is separated by areolar tissue from the 

 sterno-thyroid muscles. 



The costo-clavicular ligament (rhomboid) is a thick fasciculus of fibres, 

 connecting the sternal extremity of the clavicle with the cartilage of the 

 first rib. It is situated obliquely between the rib and the under surface 

 of the clavicle. It is in relation in front with the tendon of origin of the 

 subclavius muscle, and behind with the subclavian vein. 



Actions. The movements of the sterno-clavicular articulation, are a 

 gliding movement of the fibro-cartilage with the clavicle upon the articular 

 surface of the sternum in the directions forwards, backwards, upwards, 

 and downwards ; and circumduction. This articulation is the centre of 

 the movements of the shoulder. 



It is the rupture of the rhomboid ligament in dislocation of the sternal 

 end of the clavicle that gives rise to the deformity peculiar to this acci- 

 dent. The interarticular Jibro- cartilage is 



nearly circular in form, and thicker at 

 the edges than in the centre. It is at- 

 tached above to the clavicle ; below to 

 the cartilage of the first rib ; and through- 

 out the rest of its circumference to the 

 anterior and posterior sterno-clavicular 

 ligaments ; it divides the joint into two 

 cavities, which are lined by distinct sy- 

 novial membranes. This cartilage is 

 sometimes pierced through its centre, 

 and not unfrequently deficient, to a greater 

 or less extent, in its lower part. 



* The ligaments of the sterno-clavicular and costo-sternal articulations. 1. The ante- 

 r.oi sterno-clavicular ligament. 2. The inter-clavicular ligament. 3. The costo-clavi- 

 i , ilar or rhomboid ligament, seen on both sides. 4. The interarticular fibre-cartilage, 

 brought into view by the removal of the anterior and posterior ligaments. 5. The an 

 '.en:* costo-stemal ligaments of the first and second ribs. 



