ANATOiMV OF THE HORSE. 13 



cavities; the four hiiidermost, projecting lateral borders, which 

 incHne downwards and form the boundary lines between the in- 

 ferior and lateral surfaces. The indentations upon the fore and 

 hind parts of the separate bones, form, in the united state, 

 lateral concavities for the reception of the cartilages of the ribs : 

 the hindermost bone, itself, receiving two entire cartilages. 



The Extremities are constituted of projecting cartilages. — The 

 Carinifoim Cartilage, arising in a curve from the inferior border, 

 forms a prominent and remarkable convexity in front, flattened on 

 either side, and affords attachment to the sterno-maxillares and 

 sterno-thyro-hyoidei. — The Xiphoid or Ensiform Cartilage is 

 fixed to the last bone, and assumes a form in some measure 

 correspondent therewith, being broad and flattened above and 

 below : it is terminated however by a thin border, to the figure 

 of which it owes its name, though this is subject to much 

 variation. 



GENERAL REMARKS ON THE THORAX. 



Form. That of a truncated cone slightly incurvated, the 

 basis of which is cut obliquely, from above downward and from 

 behind forward ; the point of the apex cut off perpendicularly ; 

 the axis running in a direction from the front backward and 

 downward. 



Dimensions. The antero-posterior diameter is the greatest. 

 As we approach the apex the perpendicular more and more ex- 

 ceeds the lateral measurement; towards the basis, in conse- 

 quence of the sides diverging, these two diameters become 

 about equal. 



Division. Into two surfaces and two circumferences. 



Exterior Surface — Presenting, anteriorly, the cariniform car- 

 tilage projecting from the sternum, with its sharp edge turn- 

 ed downwards, for affording attachment to the pectoral mus- 

 cles; laterally, the convexities of the costal arches and their 

 cartilages, and between them the intercostal spaces filled by the 

 intercostal muscles ; superiorly, the dorsal spines, transverse 

 processes, and vertebral grooves; inferiorly, the sharpened lower 

 border of the sternum, terminated by the xiphoid cartilage. 



Interior Surface — Formed, below, by the incurvation of the 

 sternum and xiphoid cartilage; on the sides, by the smooth 

 concavities of the ribs together with their cartilages ; above 

 and along the middle, by the angular, smooth, descending por- 

 tions of the bodies of the dorsal vertebraB; above and along either 

 side, by an oblong fossa formed by the angles of the libs, into 

 which are received the superior thick borders of the lungs. 



