532 



MAMMALIAN ANATOMY 



upward along the anterior part of the edge of the spine to its upper 

 fourth. The lower two-thirds of this line contain the anterior or 

 cervical division of the muscle ; the upper third contains the posterior 

 or thoracic division of the muscle. The posterior part of the edge 

 of the spine gives origin to the spinous head of the deltoid, which 

 begins above at the lowest point of insertion of the posterior part of 

 the trapezius and is continued below on the upper edge of the met- 

 acromion. The acromial head of the deltoid arises from the tip, the 

 posterior edge, and the adjoining region of the inner surface of the 

 acromion, and from the anterior part of the lower edge of the met- 

 acromion. 



The vertebral border (Figs. 418, 419, 420) is arcuate and pro- 

 longed downward in front, meeting the anterior superior border in an 

 indistinct anterior angle. It forms an obtuse inferior angle with the 



axillary border. The ver- 

 tebral border is of about 

 the same width for most 

 of its extent, but where it 

 turns downward in front 

 it is narrower. It is 

 usually margined by a 

 strip of cartilage which 



420. 



RHOMBOIDEUS CAPiTIS 



Spine. 



Metacromion 



RHOMBOIDEUS MAJOR 



Vertebral Bordei 



Superior Angle. 



Coracoid Process. 



Head. 



Subscapular Fossa. 



SERRATUS MAGNUS. 



gives attachment in front 

 of the middle to the rhom- 

 boideus capitis muscle, and 

 behind this area, as far 

 back as the inferior angle, 

 on the outer side and on 

 the adjoining outer surface 

 of the bone, to the rhom- 

 boideus major, and on the 

 inner side to the serratus 

 magnus. 



^^^ The anterior superior 



border (Figs. 418, 419) is 



the shortest of the three borders. It is nearly straight, slightly 

 arcuate, and directed downward and forward. At its lower end it is 

 deeply emarginate to form the suprascapular notch. It then becomes 



Inferior Angle. 



LEFT SCAPULA, VERTEBRAL BORDER. 



