246 



APPLIED ANATOMY. 



behind nearly or quite balance each other, thus causing little or no lateral displace- 

 ment. The displacement inward and anteriorly of the lower fragment, is due to the 

 action of the violence as already detailed and is aided by the action of the pectoralis 

 major, the teres major, and latissimus dorsi muscles, all of which pass from the lower 

 fragment just below the seat of fracture inward to the trunk. 



The longitudinal displacement is peculiar. As the lower fragment is drawn up 

 its upper end may be felt through the deltoid muscle below and toward the inner side 

 of the acromion. While the displacement in most cases is not marked, in some the 

 lower fragment can readily be felt in the axilla (Fig. 261). 



Sometimes instead of the lower fragment being displaced inward it goes outward. 

 In this case as it rises it pushes the head and tilts it inward while it passes farther 

 outward. 



The diagnosis is to be made by a careful examination and comparison with the 

 opposite healthy member. The head is recognized to be in the glenoid cavity, 



Acromion process 



Supraspinatus muscle 



Clavicle 



Deltoid muscle 



Pectoralis minor 

 muscle 



Long head 

 of biceps 



Pectoralis 

 major 



Pectoralis major 



Latissimus dorsi 

 and teres major 



FIG. 261. Fracture of the surgical neck of the humerus. The upper fragment is held out by the supra- 

 spinatus, while the lower fragment is drawn in by the pectoralis major, latissimus dorsi, and teres major 

 muscles and the arm abducted by the deltoid. 



crepitus is felt, the upper end of the lower fragment can often be palpated, and on 

 rotating the arm the head of the bone is found to lie stationary. 



Treatment. The ideal treatment is extension with the patient in bed and the 

 arm abducted. As the upper fragment cannot be brought in, an effort may be 

 made to bring the lower one out. As these are usually treated as walking cases a 

 common dressing employed is a shoulder-cap with the arm bound to the side; some- 

 times an axillary pad is used to keep the arm away from the body. In cases of 

 fracture associated with luxation of the head of the bone, replacement can sometimes 

 be effected by traction in the abducted position and pressure on the head, general 

 anaesthesia being used (see description of direct method of reduction under dis- 

 location of the shoulder, page 236). 



