72 



TSE BONES. 



Fi2. 40. 



SHOULDER. 



la solipeds, this region has for its base a single bone, the scapula or 

 omoplat. 



Scapula. 



This is a flat, triangular, and asymmetrical bone, prolonged at its 

 superior border by a flexible cartilage, articulated inferiorly with the 



humerus only, and applied 

 against the lateral plane of the 

 thorax in an oblique direction 

 downwards and forwards. It 

 has two faces, three borders, and 

 three angles. 



Faces. — The external face is 

 divided by the scapular or acro- 

 mian spine, into two cavities of 

 unequal width — the supra and 

 infraspinous (or antea and postea 

 spinatus)fossse. The spine is a very 

 salient crest which runs the whole 

 length of the external scapular 

 surface ; very elevated in its 

 middle part, which shows an 

 irregular enlargement — the tube- 

 rosity of the spine — it insensibly 

 decreases towards its two ex- 

 tremities. The supraspinous 

 fossa, the narrowest, is situated 

 above, or rather in front of the 

 spine ; it is regularly concave 

 from side to side, &d perfectly 

 smooth. The infraspinous fossa 

 is twice the width of the pre- 

 ceding, and occupies all the sur- 

 face behind the spine. It ex- 



THE EIGHT SCAPULA: OUTER SURFACE. t,-i.-i. i T) l 1 X.T. ■ 



, , , . ^ , „ c • ■ ^ ■ L- hibits : 1, Below, and near the 



1, Antreior border ; 2, Superior margin for insertion ■ , • x, i ■ i 



of cartilage; 3, Tuberosity of the Spine; 4, Antea- posterior border, several rOWS 

 spinatns fossa; 5, Postea-spinatus fossa; 6, Neck of roughened lines for inuscular 

 of the scapula ; 7, Coracoid process ; 8, Glenoid insertion ; 2, Near the neck, the 

 ''^'"'y' nutritious foramen of the bone, 



and some vascular grooves. 

 The internal face is excavated in its centre to form a hollow called the 

 mibscapular fossa, which is prolonged superiorly by three diverging points. 

 The jnedian point extends to the superior border of the bone, and separates 

 two roughened triangular surfaces destined for muscular implantation. 



Borders. — The superior is indented by an irregular groove to receive the 

 inferior margin of the cartilage of prolongment. The latter is convex on its 

 superior border, extends beyond the posterior angle of the bone, and 

 gradually diminishes in thickness as it leaves its point of attachment. 

 In old horses it is nearly always found partially ossified. The anterior 

 horder, thin and sharp, is convex in its superior two-thirds, and slightly 

 concave for the remainder of its extent. The 'posterior is thicker and a Mttle 

 concave. 



