154 HUMAN EMBRYOLOGY AND MOEPHOLOGY. 



dorsal vertebrae. They are developed at the base of the trans- 

 verse processes and are for the attachment of slips of the 

 longissimus dorsi. The mammillary processes are developed on 

 the articular processes of the lower two or three dorsal and all 

 the lumbar vertebrae. They give attachment to tendons of 

 origin of the multifidus spinae. 



The Transverse and Spinous Processes grow out from the 

 vertebral bow (Fig. 119 A) into the septa between the primitive 

 segments. Each transverse process is pierced, while still in the 

 fibrous condition, by a branch of the corresponding segmental 

 (intercostal) artery. In only the cervical region do those per- 

 forating arteries and their foramina persist. In that region the 

 perforating arteries anastomose and out of the chain thus formed 

 is developed the vertebral artery. Thus the foramina for the 

 vertebral artery are formed independently of the costal element 

 in each cervical transverse process. The spines are absent on 

 the 1st cervical, 4th and 5 th sacral and coccygeal vertebrae. 

 They are slightly developed and united by ossification of the 

 interspinous ligament in the 2nd and 3rd sacral vertebrae. The 

 2nd, 3rd, 4th, 5th, and 6th cervical spines are bifid in Europeans;, 

 but in lower races, as in anthropoids, the 5 th and 6 th spines are 

 undivided. 



