LUMBAR VERTEBRA 



371 



GENERAL CHARACTERS OF THE LUMBAR 

 VERTEBRAE 



These are five, and sometimes six, in number ; the body is short and 

 thick ; broader from side to side than from before backwards ; flattened 

 superiorly, convex inferiorly, but not presenting so prominent a spinous 

 ridge as the dorsal. Its articular convexity before and concavity behind 

 assume rather an oval shape. The superior spinous process is shorter 

 than the average of the dorsal vertebrae ; it has broad, flat sides, and protu- 

 berates at the front of the summit, having a slight inclination forwards ; the 

 transverse processes, large and flattened above and below, stand out hori- 

 zontally at right angles to the body for a considerable distance, contrasting 

 strougl}' with the corresponding parts of the dorsal and cervical regions. 



Fio. IS.— Profile View op the Lumbar Verteeh^, seen from the Left. 



A. Profile view of luinljar vertobrK. 



1. 1. 1. etc. Spinous processes. 



2. 2. 2. etc. Transverse i recesses; the analogues of 



tlie ribs. 



3. 3. 3. etc. Oblique jiroccsses. 

 a. a. a. etc. Bodies. 



h. b. Articulating surfaces on trausverse processes, 



by means of which the fifth articulates 

 with a similar surface on the sixth, and 

 the sixth with a corresponding surface 

 on the sacrum. 



c. Surfaces articulating with corresponding ones 



on the last dorsal vertebra. 



d. Surfaces articulating with the sacrum. 



The oblique processes are larger than in the dorsal region ; they project 



from the roof of the arch in a horizontal direction (3^ 



Fig. 18); 



the anterior surfaces in each of these joints are concave, widely separated 

 and look inwards ; tlie posterior are convex, nearer together, and look 

 outwards. 



PECULIARITIES OF THE LUMBAR VERTEBRiE 



The fourth lumbar vertebra possesses two surfaces of articulation 

 on the posterior border of its transverse process. 



The fifth (or the sixth, if there is one) assumes somewhat the characters 

 of the first sacral bone. The transverse processes, which are longest in the 

 middle of this region, gradually shorten towards the sacrum. On the fifth 



