DEVELOPMENT OF THE ARTERIES 



26s 



Dorsal ramus. 

 Ventral ramus. 



Aorfa 



Postcostal anastomosis 

 Precostal anastomosis 



Dorsal (intersegmental) artery 



Lateral (visceral) artery 

 Ventral (splanchnic) artery 



Ventral anastomosis 

 Fig. 274. — A diagram of the trank, in transverse section, showing the arrangement of the aortic branches. 



A.v.c.v. 



Fig. 275. — The development of the vertebral and subclavian arteries and the costo-cervical trunk 

 in a young rabbit embryo (modified after Hochstetter). Ill AB.-IV AB., Aortic arches; Ap, pulmonary 

 artery; A.ii.c.h. and A.v.c.v., cephalic and cervical portions of vertebral artery; A.s., subclavian artery; 

 Co., costo-cervical trunk; C.d. and C.v., internal and external carotid arteries; ISp.C, spinal ganglion. 



subclavians from the seventh pair of intersegmental arteries (Fig. 276). In embryos 

 of 9 mm. the vertebrals in the region of the metencephalon fuse to form a single 



