6o 



ANATOMY AND PHYSIOLOGY 



Resume. With the limb in the anatomic position, observe the groove 

 for the biceps muscles on the front of the humerus, beginning between the 

 greater and lesser tubercles. In the forearm, note that the ulna is the bone of 

 the elbow-joint, while the radius makes the wrist-joint; that their shafts are 

 parallel and the palm is turned forward, and the carpus curved to help in 

 forming the hollow of the hand (or the "cup of Diogenes"), and that the 

 thumb is on the radial side, and free. 



ARTICULATIONS OF THE UPPER EXTREMITY 



Sterno-clavicular, a gliding joint (arthrodia) . This is the one 

 joint by which the upper extremity articulates with the trunk. 



Articular surfaces; on the upper angle of the manubrium and 

 the sternal end of the damcula. Anterior and posterior ligaments 



Inter-articu- 

 lar ligament 



Sterno-cos- 

 tal joint 



FIG. 55. STERNO-CLAVICULAR JOINT. (Morris.) 



The inter-articular cartilage is shown in the joint of the right side; capsules shown 



on the left side. 



connect the bones, forming a capsule. (The joint is divided by a 

 disc of fibro-cartilage into two cavities and there are two synovial 

 membranes.) 



Motions. Gliding, by which the shoulder moves upward, 

 downward, backward and forward. 



Ligaments not connected with the joint but useful in preventing dislocation: 

 Thecosto-davicular, holding the clavicle to the first rib, and the conoid and 

 trapezoid connecting it with the coracoid process of the scapula. (See Fig. 56.) 



Acromio-clavicular. A small gliding joint between the 

 acromion process of the scapula and the acromial end of the damcula. 

 It is enclosed by a capsule. 



Shoulder-joint. A ball-and-socket joint (enarthrosis) . Artie- 



