10 ANATOMY OF THE HORSE. 



vertebra dentata ; posteriorly, by the spine of the seventh ver- 

 tebra. In the back and loins, the surface offers a continued 

 series of spinal projections; long, with broad tuberous ends, 

 sloping backward, in the withers ; short, erect, with broad sides, 

 and terminated by oblong ridges, posteriorly. On the sides, 

 running close to the roots of the spinous processes, extending 

 from the dentata to the last lumbar vertebra, are the vertebral 

 grooves, filled by the spinal and semi-spinal muscles belonging 

 to the neck, back, and loins. 



Inferior Surface — Presenting great uniformity from the gene- 

 ral regularity of the inferior cervical spines and the angu- 

 lar portions of the bodies of the dorsal and lumbar vertebrae ; 

 excepting, that the sixth cervical spine is defective, and that 

 the one or two last lumbar vertebras are flattened inferiorly. 



Lateral Surfaces — Very irregular. Presenting, in the neck, 

 broad, bifid, transverse plates, with capacious vertebral channels 

 or grooves between them and the articulatory processes above, 

 which are occupied principally by the complexus major. Un- 

 derneath these grooves run the foramina for the vertebral blood- 

 vessels ; and through their sides pass the holes of conjugation. 

 — In the back and loins the holes of conjugation are situated 

 immediately behind the transverse processes; and the lumbar 

 vertebrae alone possess lateral vertebral grooves, but which are 

 very narrow compared with those along the neck. 



Extremities — Broad and articulatory. The anterior excavat- 

 ed to receive the occipital condyles ; the posterior, transversely 

 oblong, presents three smooth surfaces for articulation with the 

 sacrum. 



Vertebral Canal — Capacious and semi-oval through the neck ; 

 transversely oval and small through the back ; semi-circular 

 through the loins, and of greater diameter than in the back, less 

 than in the neck. United, anteriorly, with the cavity of the 

 cranium ; continuous, posteriorly, with the sacral canal. Con- 

 taining the spinal marrow and its membranes. 



H.— THE CHEST. (THORAX.) 



The thorax or chest is the ample conoid cavity constituting 

 the anterior part of the trunk, formed by the ribs laterally and 

 the sternum inferiorly, in which are contained the organs of re- 

 spiration and circulation. 



THE RIBS. (COSTTR.) 



Number. Thirty-six ; ranged in pairs, eighteen on either 



