APPLIED ANATOMY OF THE UPPER EXTREMITY 



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The displacement is produced as follows: inward, by the muscles passing from the thorax to 

 the outer fragment of the clavicle, to the scapula, and to the humerus viz., the Subclavius and 

 the Pectoralis minor, and, to a less extent, the Pee.oralis major and the Latissimus dorsi; back- 

 ward, in consequence of the rotation of the outer fragment. The Serratus magnus causes the 

 scapula to rotate on the thoracic wall; this carries the acromion and outer end of the outer 

 fragment of the clavicle forward and causes the piece of bone to rotate around a vertical axis 

 through its centre, and so carries the inner end of the outer portion backward. The depression 

 of the whole outer fragment is produced by the weight of the arm and by the contraction of the 

 Deltoid. The outer end of the inner fragment appears to be elevated, the skin being drawn 

 tensely over it; this is owing to the depression of the outer fragment, as the inner fragment is 

 usually kept fixed by the costoclavicular ligament and by the antagonism between the Sterno- 

 mastoid and Pectoralis major muscles. But it may be raised by an unusually strong Sterno- 

 mastoid, or by the inner end of the outer fragment getting below and behind it. The causes 

 of displacement having been ascertained, it is easy to apply the appropriate treatment. The 

 outer fragment is to be drawn outward, and, together with the scapula, raised upward to a level 

 with the inner fragment, and retained in that position. This deformity is corrected by carrying 

 the shoulder upward, outward, and backward. 



In fracture of the acromial end of the clavicle, between the conoid and trapezoid ligaments 

 only slight displacement occurs, as these ligaments, from their oblique insertion, serve to hold 

 both portions of the bone in apposition. Fracture, also, 

 of the sternal end, internal to the costoclavicular liga- 

 ment, is attended with only slight displacement, this 

 ligament serving to retain the fragments in close ap- 

 position. 



Fracture of the acromion process usually arises from 

 violence applied to the upper and outer part of the 

 shoulder; it is generally known by the rotundity of 

 the shoulder being lost, from the Deltoid drawing 

 the fractured portion downward and forward; and the 

 displacement may easily be discovered by tracing the 

 margin of the clavicle outward, when the fragment 

 will be found resting on the front and upper part of 

 the head of the humerus. In order to relax the 

 anterior and outer fibres of the Deltoid (the opposing 

 muscle), the arm should be drawn forward across the 

 thorax and the elbow well raised, so that the head of 

 the bone may press the acromion process upward and 

 retain it in its position. 



Fracture of the coracoid process is an extremely 

 rare accident, and is usually caused by a sharp blow 

 on the point of the shoulder. Displacement is here 

 produced by the combined actions of the Pectoralis 

 minor, the short head of the Biceps, and the Coraco- 

 brachialis, the former muscle drawing the fragment 

 inward, and the latter muscles directly downward, 

 the amount of displacement being limited by the 

 connection of this process to the acromion by means 

 of the coraco-acromial ligament. In many cases there appears to have been little or no 

 displacement, from the fact that the coracoclavicular ligament has remained intact, and has kept 

 the separated fragment from displacement. In order to relax these muscles and replace the frag- 

 ments in close apposition, the forearm should be flexed so as to relax the Biceps, and the arm 

 drawn forward and inward across the chest, so as to relax the Coracobrachialis; the humerus 

 should then be pushed upward against the coraco-acromial ligament, and the arm retained in 

 that position. 



Fracture of the surgical neck of the humerus (Fig. 373) is very common, is attended with 

 considerable displacement, and its appearances correspond somewhat with those of dislocation 

 of the head of the humerus into the axilla. The upper fragment is slightly elevated under the 

 coraco-acromial ligament by the muscles attached to the greater and lesser tuberosities; the 

 lower fragment is drawn inward by the Pectoralis major, Latissimus dorsi, and Teres major; 

 and the humerus is thrown obliquely outward from the side by the Deltoid, and occasionally 

 elevated so as to cause the upper end of the lower fragment to project beneath and in front of 

 the coracoid process. The deformity is reduced by fixing the shoulder, and drawing the arm 

 outward and downward. To counteract the opposing muscles, and to keep the fragments in 

 position, a conical-shaped pad should be placed with the apex in the axilla; while the forearm 

 is flexed to an angle of 90 degrees the shoulder is padded with cotton, a shoulder-cap of plaster 



FIG. 372. Fracture of the middle of the 

 clavicle. 



