THE SKELETON. 



6l 



eleventh, twelfth, and thirteenth bear a whole facet on 

 each side of the body. 



The transverse processes of the first eleven bear facets 

 for the articulation with the tubercles (Fig. 25) of the 

 ribs. The last three thoracic vertebrae are characterized 

 by mammillary processes springing from the dorsolateral 

 portion of the roots of the anterior zygapophyses. 



a 



Fi<;. 26. --CAUDAL ASPECT OF 

 FOURTH LUMBAR VERTEBRA. 



Accessory process; cr, centrum 

 or body; pa, pedicle; tr, trans- 

 verse process ; s, neural canal ; sf>, 

 spinous process ; zg, the mammil- 

 lary process of the anterior zyga- 

 pophysis; am, lamina; pz, poste- 

 rior zygapophysis. 



FIG. 27. DORSAL ASPECT OF THE 

 SACRUM. 



ft, Floor of the neural canal ; fr, dor- 

 sal aperture of the intervertebral 

 foramen; //, lateral mass; pzg, 

 posterior zygapophysis; sp, spi- 

 nous process ; si, auricular surface 

 for articulation with the ilium ; // , 

 transverse process; zgt, tubercle 

 formed by fusion of the zygapoph- 

 yses ; zg, anterior zygapophysis. 



The following features are common to all of the lumbar 

 vertebra: a spinous process projecting dorsocephalad 

 (Fig. 26) ; a transverse process projecting ventrocephalad 

 on either side from the body; anterior zygapophyses and 

 posterior zygapophyses. A mammillary process or meta- 

 pophysis is present on the root of the anterior zygapoph- 



