246 



THE ARTICULATIONS. 



clavicle, the upper and lateral part of the first piece of the sternum, and the 

 cartilage of the first rib. The articular surface of the clavicle is much larger than 



FIG. 168. Sterno-clavicular articulation. Anterior view. 



that of the sternum, and invested with a layer of cartilage l which is considerably 

 thicker than that on the latter bone. The ligaments of this joint are the 



Capsular. 



Anterior Sterno-clavicular. 



Posterior Sterno-clavicular. 



Interclavicular. 

 Costo-clavicular (rhomboid). 

 Interarticular Fibro-cartilage. 



The Capsular Ligament completely surrounds the articulation, consisting of 

 fibres of varying degrees of thickness and strength. Those in front and behind 

 are of considerable thickness, and form the anterior and posterior sterno-clavicu- 

 lar ligaments ; but those above and below, especially in the latter situation, are 

 thin and scanty, and partake more of the character of connective tissue than true 

 fibrous tissue. 



The Anterior Sterno-clavicular Ligament is a broad band of fibres which 

 covers the anterior surface of the articulation, being attached, above, to the upper 

 and front part of the inner extremity of the clavicle, and, passing obliquely 

 downward and inward, is attached, below, to the upper and front part of the first 

 piece of the sternum. This ligament is covered, in front, by the sternal portion of 

 the Sterno-cleido-mastoid and the integument ; behind, it is in relation with the 

 interarticular fibro-cartilage and the two synovial membranes. 



The Posterior Sterno-clavicular Ligament is a similar band of fibres which 

 covers the posterior surface of the articulation, being attached, above, to the upper 

 and back part of the inner extremity of the clavicle, and, passing obliquely 

 downward and inward, is attached, below, to the upper and back part of the first 

 piece of the sternum. It is in relation, in front, with the interarticular fibro- 

 cartilage and synovial membranes ; behind, with the Sterno-hyoid and Sterno- 

 thyroid muscles. 



The Interclavicular Ligament is a flattened band which varies considerably 

 in form and size in different individuals ; it passes in a curved direction from the 

 upper part of the inner extremity of one clavicle to the other, and is also 

 attached to the upper margin of the sternum. It is in relation, in front, with 

 the integument ; behind, with the Sterno-thyroid muscles. 



The Costo-clavicular Ligament (rhomboid) is short, flat, and strong: it is of 

 a rhomboid form, attached, below, to the upper and inner part of the cartilage of 

 the first rib : it ascends obliquely backward and outward, and is attached, above, 



1 According to Bruch, the sternal end of the clavicle is covered by a tissue which is rather 

 fibrous than cartilaginous in structure. 



