32 THE SKELETON OF THE HORSE 



THE CERVICAL VERTEBRAE 



These are quadrangular, massive, and longer than the vertebrae of other regions; 

 they decrease in length from the second to the last. The third, fourth, and fifth 

 are typical, and have the following characters: 



1. The bodies are long as compared with those of other vertebrae. Each 

 presents a median ventral spine or crest, which becomes more prominent as it is 

 traced backward, and is tuberculate at its posterior end. The lateral aspect is 

 concave. The dorsal surface has a flat central area which is narrow in the middle 

 of the vertebrae, and wide at either end; it gives attachment to the superior com- 

 mon ligament. On either side of this area is a groove which lodges the longitudinal 

 spinal vein. These lateral grooves are connected at the middle of the surface by 

 a transverse furrow, in which there are several foramina through which veins 

 emerge from the spongy substance of the body. The anterior extremity presents 

 a head which has an oval articular surface, strongly convex, and wider above than 

 below. The posterior extremity is larger and has a nearly circular cotyloid cavity. 



2. The arches are large and strong. They are perforated on either side by a 



Anterior articular process 



Head 



Articular cavity 

 Transverse process 



Facet for tubercle of first rib 

 Facets for head of first rib 



Fig. 8. — Last Cervical and First Thoracic Vertebr.e of Horse, Lateral View. (After Schmaltz, Atlas d. 



Anat. d. Pferdes.) 



foramen which communicates with the foramen transversarium. The verte])ral 

 notches are large. 



3. The articular processes are large. Their articular surfaces are extensive, 

 oval in outline, and slightly concave; the anterior ones are directed upward and 

 inward, the posterior downward and outward. The remaining surface is mainly 

 roughened for ligamentous and muscular attachment. A crest connects the 

 articular processes of the same side on the fourth and fifth ; on the third it does not 

 reach the anterior process. 



4. The transverse processes are large and plate-like. Each arises by two 

 roots, one from the arch and one from the body; between these is the foramen 

 transversarium, through which the vertebral artery passes. The process divides 

 externally into anterior and posterior branches, which are thickened and rough for 

 muscular attachment. 



5. The spinous process is represented by a crest (Crista spinosa), which 

 widens behind, and is connected by ridges with the posterior articular processes. 



The sixth cervical vertebra has the following distinctive features: It is shorter 

 and wider than the fifth. The arch is large, especially posteriorly. The posterior 



