LUMBAR VERTEBRAE GENERAL CONSIDERATIONS. 27 



Lumbar Vertebra. These are the largest pieces of the vertebral 

 column. The body is broad and large, 

 and thicker before than behind. The 

 pedicles very strong ; the lamina thick 

 and narrow ; the inferior interverte- 

 bral notches very large, and the fora- 

 men large and oval. The spinous pro- 

 cess is thick and broad. The trans- 

 verse processes slender, .pointed, and 

 directed only slightly backwards. The 

 superior articular processes are con- 

 cave, and look backwards and inwards ; the inferior, convex, and 

 look forwards and outwards. The last lumbar vertebra differs 

 from the rest in having the body very much bevelled posteriorly, 

 so as to be broad in front and narrow behind. 



General Considerations. Viewed as a whole, the vertebral column 

 represents two pyramids applied base to base, the superior being 

 formed by all the vertebrae from the second cervical to the last 

 lumbar, and the inferior by the sacrum and coccyx. Examined 

 more attentively, it will be seen to be composed of four irregular 

 pyramids, applied to each other by their smaller extremities and by 

 their bases. 'The smaller extremity of the uppermost pyramid is 

 formed by the , axis, or second cervical vertebra ; and its base, by 

 the first dorsal. The second pyramid is inverted ; having its base 

 at the first dorsal, and the smaller end at the fourth. The third 

 pyramid commences at the fourth dorsal, and gradually enlarges 

 to the fifth lumbar^ The fourth pyramid is formed by the sacrum 

 and coccyx. 



The bodies of the vertebras are broad in the cervical region, nar- 

 rowed almost to an angle in the middle of the dorsal, and again 

 broad in the lumbar region. The arches are broad and imbricated 

 in the cervical and dorsal regions, the inferior border of each over- 

 lapping the superior of the next. In the lumbar region they are 

 narrow, and leave a considerable interval between them. 



The spinous processes are horizontal in the cervical, and become 

 gradually oblique in the upper part of the dorsal region. In the 

 middle of the dorsal region they are nearly vertical and imbricated, 

 and towards its lower part assume the direction of the lumbar 

 spines, which are quite horizontal. The transverse processes deve- 

 loped in their most rudimentary form in the axis, gradually increase 

 in length to the first dorsal vertebra. In the dorsal region they 

 project obliquely backwards, and diminish suddenly in length in the 

 eleventh and twelfth vertebrae, where they are very small. In the 

 lumbar region they increase to the middle transverse process, and 

 again subside in length to the last. The inter vertebral foramina 

 formed by the juxtaposition of the notches, are smallest in the cer- 



* A lateral view of a lumbar vertebra. 1. The body. 2. The pedicle. 3. The 

 superior intervertebral notch. 4. The inferior intervertebral notch. 5. The spinous 

 process. 6. The transverse process. 7. The superior articular processes. 8. The 

 inferior articular processes. 



