194 SURGICAL APPLIED AM ATOMY. [Chap. xi. 



line of action of the trapezius muscle is altered by the 

 fracture, that muscle is no longer able to keep the 

 shoulder up, and its altered action therefore contri- 

 butes to the downward displacement. (2) It is carried 

 directly inwards by the muscles that pass from the 

 trunk to the shoulder, viz. the trapezius, the levator 

 anguli scapuhe, the rhomboids, the latissimus dorsi, and 

 especially by the pectorals. To these may be added 

 the subclavius. (3) The fragment is rotated in such a 

 way that the outer end projects forwards and the 

 inner end back. This rotation is brought about 

 mainly by the two pectoi-als assisted prominently by 

 the serratus magnus. The normal action of this latter 

 muscle is to carry the scapula forwards, and the 

 clavicle, acting as a kind of outrigger to keep the 

 upper limb at a proper distance from the trunk, moves 

 forwards at the same time and keeps the scapula 

 direct. When this outrigger is broken the serratus 

 can no longer carry the scapula directly forwards. 

 The bone tends to turn towards the trunk, and the 

 point of the shoulder is therefore seen to move inwards 

 as well as forwards. The fragments in this fracture 

 must consequently overlap, and as the displacement is 

 difficult to remedy, it follows that in no bone save tha 

 femur is shortening so uniformly left as after an 

 oblique fracture of the clavicle. The degree of 

 shortening very seldom exceeds one inch. The 

 deformity associated with this fracture is well 

 remedied when the patient assumes the recumbent 

 position. In this posture, the weight of the limb 

 being taken off, the downward displacement is at 

 once remedied. The point of the shoulder falling 

 back also tends to relieve in part the inward displace- 

 ment, and the rotation of the outer fragment forwards. 

 It is through the scapula, however, that these two 

 latter displacements are in the main removed. In 

 the recumbent posture the scapula is pressed dosr-ly 



