THE THORAX. 



71 



2. Ribs. 



The number of ribs varies like that of the dorsal vertebras. The following table 

 indicates the number of these bones in the different domesticated animals. 



Pig 

 Ox 



Goat 

 Dog 



14 

 13 

 13 

 13 

 13 



KUMINANTS. These animals have eight sternal and five asternal ribs. 



In the Ox, they are longer, wider, and less arched than in solipeds. The articular 

 eminences of the superior extremity are voluminous and well detached ; the neck 

 especially is very long. The sternal ribs are joined to their cartilage of prolongment by 

 a real diavthrodial articulation. In the last rib, and sometimes in the one before it, 

 the tuberosity is scarcely perceptible, and has no articular facet. In the Sheep and Goat, 

 the sternal ribs are consolidated with the cartilages (see fig. 5.) 



PIG. In this animal there are fourteen pairs of ribs, seven of which are sternal and 

 seven asternal. The first are provided with cartilages of prolongment flattened on both 

 sides, extremely wide and sharp, and convex on their superior border. In the four last 

 asternal ribs, the facet of their tuberosity is confounded with the posterior facet of the 

 head. (Otherwise, the ribs of the Pig resemble, in their general conformation, those of 

 the Sheep or Goat ; though more incurvated and wider.) 



CARNIVORA. They possess thirteen ribs Fig. 39. 



on each side nine sternal and four asternal. 7 



These are very much arched, narrow, and 

 thick, and their cartilages rarely ossify. In 

 the Dog, the articular facet of the tuberosity 

 remains isolated from the posterior facet of 

 the head in all the ribs. It is absent in the 

 three last ribs of the Cat. 



COMPARISON OF THE THORAX OF MAN WITH 

 THAT OF THE DOMESTICATED ANIMALS. 



1. Sternum. 



The sternum of Man is flattened before 

 and behind, and diminishes in width from 

 above to below. The xiphoid appendage is 

 narrow, and single or bifid. Besides the 

 articular surfaces for the ribs, there are found 

 on the upper end two lateral notches for 

 articulation with the clavicles. 



2. Ribs. 



Of the twelve ribs in Man, seven are 

 sternals and five asternals. They are 

 short, narrow, and much incurvated, especially 

 the first ones. In each rib the curvature is 

 more marked in the posterior fourth or fifth 

 than in the anterior three-fourths or four- 

 fifths ; this sudden change of curvature is 

 indicated in the external face by a kind of 

 inflexion and thickening called the angle of 

 the ribs. The prolonging cartilages of the 

 eleventh and twelfth ribs are short, and are 

 lost in the texture of the abdominal parietes ; 

 for this reason they are termed the floating (or 

 false) ribs (see fig. 39). 



THORAX OF MAN; ANTERIOR FACE. 

 1, Superior piece of the sternum; 2, 

 Middle piece, or body ; 3, Inferior piece, 

 or ensiform cartilage; 4, First dorsal 

 vertebra; 5, Last dorsal vertebra; 6, 

 First rib; 7, Its head; 8, Its neck, rest- 

 ing against the transverse process of the 

 first dorsal vertebra; 9, Its tubercle ; 10, 

 Seventh, or last true rib; 11, Costal car- 

 tilages of the true ribs ;' 12, The last two 

 false or floating ribs; 13, The groove 

 along the lower border of the rib. 



ABTICLE IV. ANTERIOR LIMBS. 



The anterior (or thoracic) limb is divided into four secondary regions : 

 the shoulder, arm, fore-arm, and fore-foot or hand. 



