12 LABORATORY DIRECTIONS 



by a narrow ventral arch. The transverse processes are large 

 and wing-like, and are pierced near the base by foramina trans- 

 versaria for passage of the vertebral artery. The cranial artic- 

 ular processes for receiving the occipital condyles of the skull 

 are large. Dorsal to them lie the atlantal foramina for the 

 continuation of the vertebral artery. The caudal articular 

 facets articulate with the second vertebra. 



Axis. — This is the second cervical vertebra. The projection 

 at the anterior end of its centrum is the odontoid process (odon- 

 toid, toothlike), which is really the centrum of the atlas. 

 Observe particularly: the small transverse processes, the for- 

 amina transversaria, the large cranial articular facets, the neural 

 spine, and the caudal articular facets. 



Cervical Vertebrae. — Notice the gradual transition in 

 them. On some the transverse processes arise by two roots, one 

 from the centrum and one from the arch. Between the two lies 

 t\\& foramen transversarium for the vertebral artery. The trans- 

 verse process divides distally into a dorsal projection represent- 

 ing the transverse process proper, and a ventral costal process 

 representing a rib. Observe differences between different 

 cervical vertebrae in this respect. 



Lumbar Vertebrae. — These are larger than the thoracic, 

 the transverse processes are more complicated in structure, the 

 spinous processes are shorter, and there are no ribs. 



Sacral Vertebrae. — These, usually three in number In the 

 cat, are united In the adult Into a single bone, the sacrum. 

 What evidence is there of the multiple character of the sacrum ? 



Caudal Vertebrae. — These gradually decrease in size, 

 becoming longer and more slender, and finally are reduced to 

 mere centra. In life several of the caudal vertebrae, after the 

 third, bear haemal processes tipped by chevro7i hones to form a 

 haemal canal. The chevron bones are usually lost In preparing 

 the skeleton. 



Examine a cervical vertebra of a horse. Is the centrum pro- 

 coelus or opisthocoelus (convex anteriorly, concave posteriorly) .'' 



Sternum of the Cat 



Locate the sternum or breast bone on a mounted skeleton. 

 It is made up of eight pieces, called sternebrae, distributed over 

 three regions as follows: 



