THE LUMBAR VERTEBRAE. 



11 



The eleventh dorsal vertebra has a complete articular surface on each side 

 for the head of the rib, but no facet on the transverse process. 



The twelfth dorsal vertebra has also only a single facet on each side ; the 

 inferior articular processes have their surfaces turned outwards, resembling those of 

 a lumbar vertebra ; the transverse processes are short and present three elevations, 

 the external, superior, and inferior tubercles, which correspond to the transverse, 

 mamillary, and accessory processes of the lumbar vertebras. Indications of these 

 tubercles may often be seen also upon the tenth and eleventh vertebrae. 



Varieties. The ninth dorsal vertebra frequently wants the lower facet on the side of the 

 .body. The tenth dorsal vertebra sometimes has no facet on the transverse process. The 

 change from the dorsal to the lumbar type of articular processes occasionally takes place 

 between the eleventh and twelfth dorsal vertebras. 



Lumbar vertebrae. These are five in number, the largest of the moveable 

 vertebras, and are distinguished by the absence of costal articular surfaces. 



The body has a greater diameter transversely than from before backwards, 



MAMII_1_ARY PROC. 

 ACCESSORY PROC. 



RACOSVERSE PROC. 



SUP. ARTICULAR PROC. 



Fig. 10. THIRD LUMBAR VERTEBRA, FROM ABOVE. (Drawn by D. Gunn.) 



and viewed from above or below its surface presents a reniform outline ; the depth is 

 generally slightly greater in front than behind. 



The lamince are shorter, deeper, and thicker than those of the dorsal vertebrae. 

 The superior notches are shallow, the inferior deep. 



The spinous process projects horizontally backwards. It has considerable breadth 

 from above downwards, and is thickened and rough along its posterior edge. 



The transverse processes, slender and somewhat spatula-shaped, project directly 

 outwards ; they are shortest in the first, longest in the third vertebra. Their 

 extremities lie in series with the external tubercles of the lower dorsal transverse 

 processes, and with the ribs. Behind each at its base is a small process pointing 

 downwards, which corresponds to the inferior tubercle of the dorsal transverse 

 process, and is called the accessory process (anapophysis). 



The articular processes are thick and strong. Their articular surfaces are vertical j 



