298 



Tlie most detailed report concerning tlie development of the shoulder- 

 blade is that by Bhyck and Broman. From their figures it is evident 

 that they derive their data from Lewis, who published in the American 

 Journal of Anatomy (Vol. I 1901 — '02) a minute description of the 

 development of the arm in man. Broadly stated his data agree with 

 those of BttYCE, mentioned above. They differ, however, as to the spina, 

 scapulae. According to Lewis the S|)ina probably takes origin in the 

 upper margin of the scapula. This margo superior thickens and then 

 splits into a medial and a lateral lip. The medial lip is the future 

 margo superior, the lateral one is the first beginning of the spina scapulae. 



Hagen') descril^es a shoulder-blade of an embryo 17 mm. in length. 

 The spina scapulae is absent, the proc. coracoi'deus is large, the proc. 

 acroniialis small. The latter statement cannot be reconciled with Lewis's 

 communication, which, on the contrary, speaks of a relatively large 

 proc. acromialis. 



This review of the literature would not be complete without 

 mentioning the interesting study liy Ruthehfokd^) who entered into 

 many details of the development of the shoulder-blade. Like Lewis he 

 constructed wax models of the skeleton of the shoulder-girdle, and 

 i. a. found that the s|)ina scapulae originates in very early ossi- 

 fication of derivates of cartilage cells, situated between M. supra- and 

 infraspinatus. 



From this review it is clear that our knowledge of the modus of 

 development of the shoulder-blade in man is still limited. The 

 shape in the initial stages of development is described differently. 

 Conflicting views are held as to the genesis of the spina and from 

 the contents of this paper it will be seen that these are not the 

 only points of controversy. 



With a view to trace the development of the shoulder-blade in 

 man, 1 constructed wax models of various stages of develo|)nient. 

 Fig. 1 represents the wax model of the shoulder-blade of the youngest 

 embryo, 16 mm. in length. The scapula is drawn from the lateral 

 side and from above. 



The reconstruction shows: 



1'. that the shoulder-blade lies in a sagittal plane, so that the 

 lower half is in contact with the three upper ribs. Processus acro- 

 mialis and clavicula are not in contact as yet. 



2". that the processus coracoi'deus is large; the processus acro- 

 mialis is relatively small. The joint-cavity rests chiefly on the 

 processus coracoi'deus. 



1) Arch. f. Anal. u. Entwickel. GescL. 1900. 

 ') Journal of Anatomy and Physiology 1914. 



