116 CLINICAL APPLIED ANATOMY. 



the coracoid, the posterior surface of the anatomical neck resting 

 as a rule upon the anterior margin of the glenoid fossa. It will 

 thus be seen that, strictly speaking, the position is rather intra- 

 coracoid than sub-coracoid. The subscapularis muscle is usually 

 lacerated during the displacement of the head, although sometimes 

 it remains untorn, but greatly stretched over the surface of the 

 bone. The supraspinatus, infraspinatus and teres minor are 

 taut over the now-empty glenoid fossa; and in some instances 

 they may drag off the great tuberosity of the humerus. 



If the head of the humerus is displaced still further inwards, so 

 as to lie between the pectoral muscles and the serratus magnus 

 a position which can only be assumed in a wide laceration of 

 the capsule with the muscles attached to it the dislocation is 

 frequently termed sub-clavicular. 



As a rule there is marked evidence from examination of the 

 shoulder- joint that one of these two forms of dislocation has 

 occurred. The first obvious sign is that, owing to the displace- 

 ment of the head inwards, the deltoid muscle will pass vertically 

 from its attachment to the acromion to the outer side of the shaft 

 of the humerus, its fibres being no longer raised and curved by 

 the head articulating with the glenoid fossa. The affected 

 shoulder thus appears distinctly flattened. For the same reason 

 a straight line, such as the edge of a splint, can now touch the 

 tip of the acromion process and the external condyle of the 

 humerus at one and the same time, whereas in the normal 

 condition the axis of the humerus will prevent this. 



Further the anterior wall of the axilla may be bulged, and the 

 infraclavicular fossa obliterated. Thus it comes about that 

 the vertical measurement round the shoulder and axilla will be 

 greater on the affected than on the sound side. 



Again, the range of movement at the dislocated shoulder is 

 decidedly limited, and it will be found that the sufferer is unable 

 to place the palm of the hand of the affected limb upon the 

 opposite shoulder with the elbow applied to the side of the chest, 

 owing to the long axis of the humerus being now directed 

 downwards and a good deal outwards. 



