51 LUMBAR VERTEBRAE. 



backwards. The superior articular processes are concave, and look back- 

 wards and inwards ; the inferior convex, and look forwards and outwards. 

 Projecting backwards and upwards from the superior articular process is 

 a short and flattened tubercle or posterior transverse process, and in a 

 strongly marked vertebra there is not unfrequently at the base of this a 

 smaller tubercle which has a direction downwards. The last lumbar ver- 

 tebra differs from the rest in having the body very much bevelled poste- 

 riorly, so as to be thick in front 'and thin behind, and the transverse pro- 

 cess thick and large. 



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 ver- 

 tebra ; 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 vertebrae are broad ia the cervical region ; narrowed 

 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 overlapping the superior of the 

 next ; in the lumbar region an interval is left between them. A consider- 

 able interval exists between the cranium and atlas, and another between 

 the last lumbar vertebra and sacrum. 



The spinous processes are horizontal in the cervical, and become gradu- 

 ally 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, w T hich are quite 

 horizontal. The transverse processes developed 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 sud- 

 denly in length in the eleventh and twelfth vertebrae where they are very 

 small. In the lumbar region they increase to the middle transverse pro- 

 cess, and again subside in length to the last. 



The transverse processes consist essentially of tw r o parts, the anterior 

 of which in the dorsal region is the rib, while the posterior retains the 

 name of the transverse process. In the cervical region these two elements 

 are quite apparent, both by their different points of attachment to the ver- 

 tebra, and by the vertebral foramen which divides them at their base. In 

 the lumbar region the so-called transverse processes are in reality lumbar 

 ribs, while the transverse processes will be found behind them in a nuli- 

 rnentary state, developed, like the true transverse processes in the cervical 

 region, from the superior articular processes. When the anterior and 

 posterior transverse processes are examined in relation with each other, 

 they will be observed to converge ; if they were prolonged they would 

 unite as in the cervical region and enclose a foramen, or they would rest 

 in contact as in the dorsal region, or become consolidated as in the form- 

 ation of the sacrum. Moreover, the posterior transverse processes 'ire 



