THE ELBOW-JOINT 135 



serratus magnus pull the inferior angle of the scapula forward, 

 rotating that bone, which raises its external angle. Two other 

 joints share the motion the acromioclavicular until its yielding 

 is stopped by the coracoclavicular ligaments, next the sterno- 

 clavicular joint until its motion is checked by the costoclavicular 

 ligament. So three chief muscles are concerned in raising the 

 hand above the head, and 'two joints besides the shoulder- 

 joint. Freest motion is up and forward. The angle between 

 the scapula and clavicle changes to secure adaptation of the 

 former to the chest wall. 



Adduction is accomplished by the subscapularis, pectoralis 

 major, latissimus dorsi, and teres major. Total rotation is 

 through 90 degrees, limited by capsule and muscles; it is freest 

 externally and backward; rotation in is produced by the sub- 

 scapularis, latissimus dorsi, and teres major; rotation out by 

 the infraspinatus, supraspinatus, and teres minor. Circum- 

 duction is a combination of all the angular movements in 

 succession. 



The Elbow-joint 



The elbow is a hinge-joint formed by the trochlea of the 

 humerus resting in the greater sigmoid cavity of the ulna; 

 while the capitellum or radial facet of the humerus articulates 

 with the lesser sigmoid cavity of the ulna. 



The ligaments are capsular, with thickened bands and the 

 orbicular ligament; the thickened bands are known as anterior 

 and posterior, internal lateral and external lateral. 



The capsule includes the coronoid and part of the olecranon 

 fossae, a part of the internal epicondyle, but not the external, 

 the tips of the coronoid and olecranon processes. The anterior 

 thickened portion of the capsule passes from the point of the 

 inner epicondyle and from the front of the humerus above 

 the coronoid fossa to the anterior margins of the coronoid 

 process, and externally into the orbicular ligament. Super- 

 ficially is an oblique band passing down and out from the 

 internal epicondyle to the orbicular ligament. The fibers 

 under these are vertical, the anterior ligament of Barkow, and 

 the deepest are transverse. The posterior part of the capsule 

 passes from the lower end of the humerus, leaving the upper 

 part of the olecranon fossa exposed to the posterior and external 

 margins of the olecranon process, a little behind the articular 



