XV, 6 
Canizares : Abnormalities of Vertebral Artery 455 
External carotid 
■ Internal carotid 
.Common carotid 
Vertebral artery 
Dorsal aorta 
Ventral aorta 
Aortic arch 
Ductus arteriosus 
Right pulmonary 
artery 
Subclavian artery 
Left pulmonary artery 
Trunk of pulmonary artery 
Fig. 1 . Diagram, showing the aortic arches and their derivatives in human embryos with 
normal origin of vertebral arteries (modified after Prentiss). 
on the left side, and the innominate and the proximal portion 
of the subclavian upon the light. 
Prentiss (6) says: 
The ventral longitudinal anastomosis of the dorsal rami of the first 
seven pairs of dorsal intersegmental arteries, gives rise to the vertebral 
Vertebral 
arteries Seventh pair of 
Cephalic aortic arches 
Fig. 2. Diagram, showing stage of five aortic arches and origin of the vertebral arteries 
(modified after Cunningham). 
