2 THE SUPERIOR EXTREMITY 



It is essential, therefore, that the student should train his 

 eyes to see all that can be seen, and his fingers to feel all 

 that can be felt, and he must remember that anything which 

 he can see or feel in the case of the body of another person 

 he can almost equally well see and feel in the case of his 

 own body. 



The bones of the superior extremity are the clavicle (collar 

 bone) and the scapula (shoulder blade), the humerus, the 

 radius and the ulna t eight carpal bones, five metacarpal bones, 

 w\& fourteen phalanges (Figs, i, 2, 3). 



The scapula and clavicle, together, form the shoulder girdle, 

 by means of which the arm is articulated with the skeleton of 

 the trunk. 



The clavicle can be seen and felt at the lower part of the 

 front of the neck. It extends from the shoulder to the upper 

 end of the sternum .(breast bone), which lies in the middle 

 part of the front of the chest. Below the junction of 

 its intermediate and lateral thirds is a depression of the 

 surface, the delto-pectoral triangle. The soft prominence to 

 the medial side of the delto-pectoral triangle is caused by the 

 portion of the pectoralis major muscle which is attached to 

 the front of the medial half of the clavicle, and the prominence 

 on the lateral side of the triangle is due to the anterior part 

 of the deltoid muscle which springs from the front of the 

 lateral third of the clavicle. If the finger is pressed upwards 

 and backwards at the upper part of the lateral margin of 

 the delto-pectoral triangle, a prominence of bone called the 

 coracoid process of the scapula will be felt. It lies under cover 

 of the medial edge of the deltoid muscle, and is an important 

 landmark (Figs, i, 2, 55, 56, 57). 



Beyond and behind the lateral end of the clavicle a more 

 or less quadrangular plate of bone can be felt. It is the 

 acromion of the scapula. Its medial margin articulates with 

 the lateral end of the clavicle, at the acromio-clavicular joint. 

 Its lateral margin lies at the tip of the shoulder, and it is the 

 upper point from which the length of the superior extremity 

 is measured. 



On the posterior aspect of the body running, medially, 

 backwards and slightly downwards, from the acromion is a 

 prominent and easily felt ridge of bone. It is the posterior 

 border or crest of the spine of the scapula. 



In the arm there is one bone, the humerus. It extends 



