PECTORAL REGION 3 



from the shoulder, where it articulates with the scapula, to the 

 elbow, where it articulates with the bones of the forearm , they 

 are the radius on the thumb or lateral side, and the ulna on 

 the medial or little finger side. 



When the fingers are placed on the lateral side of the arm 

 immediately below the acromion and the arm is moved in any 

 direction, the proximal end of the humerus can be felt moving 

 under cover of the deltoid muscle ; the part of the humerus 

 which is felt is mainly the greater tubercle (Figs, i, 2, 55, 56). 



The angular interval between the proximal part of the arm 

 and the chest wall is the axilla. It contains important blood- 

 vessels, nerves, and lymph glands. If the fingers are pushed 

 well up into the axilla and the arm is moved, the lower part 

 of the rounded head of the humerus, which articulates with 

 the scapula, can be felt. In front of the fingers will be the 

 anterior wall of the axilla, formed almost entirely by muscle; 

 behind them will be the posterior wall, formed by muscles and 

 by the axillary border of the scapula, which can be felt. To 

 the medial side are the upper ribs of the chest wall, covered 

 by a muscle called the serratus anterior-, and laterally is the 

 humerus. 



The student should follow the body or shaft of the 

 humerus from its proximal to its distal end, squeezing the 

 soft parts between his thumb and fingers ; as the region of 

 the elbow is approached he will find that the humerus 

 expands greatly from side to side and that its medial and 

 lateral margins terminate in projections, which are called the 

 epicondyles of the humerus (Figs, i, 2, 85). 



Both are landmarks. Behind the medial epicondyle lies 

 the ulnar nerve ; it can be felt quite easily in the living body 

 if a finger is pressed against the back of the epicondyle and 

 is moved from side to side. If the pressure is sufficiently 

 strong it gives rise to a tingling sensation along the medial 

 part of the hand. 



Anterior to the lateral epicondyle and somewhat to its 

 medial side another large nerve, the radial, breaks up into 

 its terminal branches ; it cannot, however, be felt. 



The posterior border of the ulna is subcutaneous in the 

 whole of its length. It extends from the olecranon, which is 

 the prominence at the back of the elbow, to a small pointed 

 process called the styloid process of the ulna which lies at the 

 medial side of the back of the wrist (Figs, i, 2, 3, 97, 98, 99). 

 i la 



