THE SCAPULA. 



251 



short predavicular border in front of this, receiving the outer end of the coraco- 

 acromial hgament, runs forward and outward to the anterior tubercle. From this 

 the outer border runs backward to the tnetacromial tubercle, whence the posterior 

 border runs into the hind edge of the spine. The outer border has three or four 

 irregularities above for the tendinous septa of the deltoid, and is smooth at its lower 

 edge for the same muscle. The lower lip of the spine runs directly into the hind 

 border of the acromion, but often splits so as to enclose a harrow space continued into 

 the back of the process, from which the deltoid springs. The acromion varies much 

 in shape ; according to this description it is quadrate ; often, however, the pre- 



FiG. 270. 



SUPERIOR ANGLE 



O 



c 



Levator angult scapulae 



Supraspinatiis 



Trapezius 



Rhomboideus 

 minor 



Smooth sur- 

 face for tra- 

 pezius 



Coraco-acromial ligament 



coRACoiD PROCESS Bleeps and coraco- 



bracln'alis 



ACROMION 



tubefcle 



Deltoid 



acromial tubercle 



Triceps, long head 

 Groove for dorsal artery- 



INFERIOR ANGLE 



Teres major 



-Occasional origin of latissinius dorsi 

 Right scapula from behind. 



clavicular edge is rudimentary, so that it is three-sided ; or the metacromial tubercle 

 is at the apex of a very obtuse angle, so that it is curved and narrow. There are 

 also intermediate forms. ^ The inclination of the acromion to the horizon is on an 

 average not far from 45°, with a variation of probably 15° either way. This may or 

 may not depend on a corresponding variation of slant in the spine. 



All the details determining the outline of the scapula vary greatly. The hind border may 

 be convex, or the infraspinous portion concave. The bone lying with the dorsum up should 

 rest on the coracoid and the upper and lower angles, with the vertebral edge rising from the 

 table ; but this may be almost straight, or even Ijend the other way so as to change the usual 

 points of support. The length from" the upper to the lower angle ranges from 13.2 centimetres 



^ Macalister : Journal of Anatomy and Physiology, vol. xxvii., 1893. 



