PRACTICAL CONSIDERATIONS : THE SCAPULA. 255 



nant neoplasm, subperiosteal and central sarcomata especially. The main danger 

 of the operation is hemorrhage. The subclavian should, therefore, be controlled. 

 The dorsalis scapulae, crossing the axillary border of the scapula at a point on a level 

 with the centre of the vertical axis of the deltoid (Treves), and the subscapular run- 

 ning along the lower border of the subscapularis muscle to reach the inferior angle, 

 are the largest vessels that require division, but the suprascapular, posterior 

 scapular, and branches of the acromio-thoracic artery will also be cut. 



Infectious diseases giving rise to caries and necrosis and to suppuration are 

 rare. When they affect the supraspinous region the pus is directed forward by the 

 fascia covering the supraspinatus, which encloses that muscle in an osseo-fibrous 

 compartment. In the infraspinous region the still denser infraspinous fascia con- 

 ducts the pus in the same direction ; hence abscesses originating in scapular dis- 

 ease are likely to point near the axilla and in the neighborhood of the insertions of 

 the scapular muscles into the humerus. On the under surface of the scapula, between 

 the ridges which give origin to the tendinous fibres that intersect the subscapularis 

 muscle, the periosteum is loose and easily separated. Suppuration following caries 

 of this aspect of the bone may, therefore, cause extensive detachment of the perios- 

 teum, and it has been found necessary to trephine the thin portion of the blade of 

 the scapula to give vent to such a purulent collection. 



Landmarks. — The greatest breadth of the scapula is in a line from the glenoid 

 margin to the \'ertebral border ; the greatest length in a line from the superior to 

 the inferior angle. 



The general outlines of the scapula can easily be felt. The bony points most 

 readily recognized by touch are the acromion, the coracoid, the spiae, the vertebral 

 edge, and the inferior angle. 



The edge of the acromion is an important landmark. Measurement from it to 

 the suprasternal notch is the easiest way of determining shortening in fracture of the 

 clavicle. If this measurement is less than on the sound side, and the clavicle itself 

 is unchanged in length, it indicates a dislocation of the acromial end of the latter. 



Undue prominence of the edge of the acromion is seen in luxation of the 

 humerus (page 582) and in fracture of the neck of the scapula. In these conditions 

 the fingers may be pressed beneath the acromion, as they can in old cases of deltoid 

 paresis or paralysis with atrophy of that muscle, when the weight of the arm drags 

 the humerus downward and increases the space between the greater tuberosity and 

 the acromial edge. 



The coracoid process may be felt through the inner deltoid fibres, below the 

 inner portion of the outer third of the clavicle, by thrusting the fingers into the 

 space between the pectoral and deltoid. In fracture it may be depressed, as it is in 

 fracture of the scapular neck. The axillary artery can be felt just to the inner side 

 of the coracoid as it passes over the second rib. 



The spine is least prominent in muscular and most conspicuous in feeble and 

 emaciated persons. This is also true of the inferior angle, which in weak, and 

 especially in phthisical, subjects is not held tightly to the chest, but projects in a 

 wing-like manner (scapulae alatae). This is partly due to general muscular weak- 

 ness, in which the latissimus dorsi and serratus magnus participate, and partly to 

 the shape of the thorax and the direction of the clavicles. The flatter and shallower 

 the chest the more oblique in direction and the lower are the collar-bones, carrying 

 with them downward and forward the upper and anterior portions of the scapulae, 

 and by that much tending to make the lower and posterior portions more promi- 

 nent. 



The length of the arm is usually measured from the junction of the spine of the 

 scapula and the acromion — the acromial angle — to the external condyle of the 

 humerus. 



The vertebral edge of the scapula lies just at the side of the spinal gutter. 

 When the arm hangs at the side of the body, this edge is parallel with the lina 

 of the spinous processes. It can be made prominent (for palpation) by carrying 

 the hand of the patient over the opposite shoulder. The superior angle is made 

 accessible by the same position. The axillary border of the scapula and the inferior 

 angle are best examined with the elbow flexed and the forearm carried behind the 



