TBE ECTAL ASPECT OF TSE SCAPULA. 



155 



^^''- 



■X 





projects sharply entad between the Fs. glenoidea and the Mrg. coracoideus. From its 

 extremity arises the M. eoracuideus (Fig. 75). 

 Ridges. — See Fs. subscapular is. 

 Tiiierculum Bieipitale.—%&& Fig. 46. 

 § 390. Description 

 of Fig. 44,— The ectal 

 aspect of the scapula. 



The principal feature 

 of this surface is the sub- 

 triangular lamina which 

 projects therefrom ; its 

 direction is approximately 

 longitudinal, but it is 

 more nearly parallel with 

 the longer part of the 

 coracoid border, and it 

 inclines in the opposite 

 direction. It begins as 

 a triangular elevation at 

 the vertebral border of 

 the scapula, and rises 

 rapidly to about the mid- 

 dle of the length of the 

 bone, where its edge is 

 thickened and roughened. 

 From this point toward 

 the glenoid end its eleva- 

 tion remains nearly uni- 

 form, but there are pro- 

 jections which will be 

 described presently. This 

 ectal ridge is the mesoscapula or spine of the scapula. 



§ 391. In the light of Embryology and Comparative Anatomy, the entire scapula may 

 be regarded as essentially a subcylindrical bar. With most Mammals the sides are pro- 

 duced in three directions so that a transection is irregularly T-shaped ; the upright of the 

 T represents the ectal ridge just described, and the two arms of the cross-piece represent 

 the two laminae at right angles therewith which constitute the principal part of the bone, 

 and whose borders are respectively glenoid and coracoid. By Parker (A, 215), these three 

 regions are called respectively mesosca/pula, postscapula and prmscapida. 



Consistently with these names, the glenoid border should be called Mrg. postscapularis, 

 and the coracoid Mrg. prmscapvlaris ; the fossae between them and the mesoscapula should 

 also be similarly designated. Since, however, the anthropotomical name for mesoscapula 

 is spine, and in the natural attitude of man its direction is approximately horizontal, these 

 ■ fossse have been named iufraspinous and supraspinous, while the muscles arising there- 

 from are called infraspinatus and supra^pinatus. Until it shall be agreed to change the 

 names of these muscles, it will probably be more convenient to retain the anthropotomical 

 names for the fossae. 



§ 893. Acromion — Pre. acromialis — Acromion process (Fig. 30, 43, 46, 47). — This forms 

 the free extremity of the mesoscapula. Its ectal border is deflected slightly from the line 

 of the mesoscapula toward the coracoid border. In man it articulates with the clavicle, 

 but in the cat it is connected therewith by only a slender ligament or strip of fascia. 



Fig. 44.- 



-The Ectal Aspect of an Adult Left Scap- 

 ula ; X 1. 



