162 



f art 



THE UPPER EXTREMITY 



CHAPTER XL 



THE REGION OF THE SHOULDER. 



A STUDY of the region of the shoulder comprises 

 the clavicle, the scapula, the upper end of the humerus, 

 and the soft parts that surround them, together with 

 the shoulder joint and axilla. 



Surface anatomy. The clavicle, acromion pro- 

 cess, and scapular spine are all subcutaneous, and can 

 be readily felt. In the upright position, when the 

 arm hangs by the side, the clavicle is, as a rule, not 

 quite horizontal. In well-developed subjects it inclines 

 a little upwards at its outer end.* In the recumbent 

 posture, the weight of the limb being taken off, the 

 outer end rises still higher above the sternal extremity. 

 The degree of the elevation can be best estimated by 

 a study of frozen sections. Thus, in making horizontal 

 sections of the body, layer by layer, from above down- 

 wards, Braune found that by the time the sterno- 

 clavicular articulation was reached, the head of the 

 humerus would be cut across in the lateral part of 

 the section (Fig. 17). 



The deltoid tubercle of the clavicle may, if large, 

 be felt through the skin, and be mistaken for an 

 exostosis. The acromio-clavicular joint lies in the 

 plane of a vertical line passing up the middle of the 



* In some women, in the feeble, and in some narrow-shoul- 

 dered men, the clavicle may be horizontal, or its outer end may 

 incline downwards. 



