CONTENTS. 



PAGE 



Introduction 49 



Branchial phase of aortic arches 50 



Plexiform origin of arches 52 



Successive development of arches and shifting of current 53 



So-called fifth arch Morphology of pulmonary arch 56 



Ventral connections of aortic arches Aortic sac 58 



Involution of first and second aortic arches Origin of stapedial and external carotid 



arteries 60 



Post-branchial phase 62 



Topography of aortic-arch system and its derivatives 73 



Fusion of primitive aorta? 73 



Migration of aortic-arch system 77 



Longitudinal shifting of aorta 77 



Shifting of arches and their ventral connections 79 



Relation of migrating arch and its branches to superior aperture of thorax 82 



Individual arteries 83 



Pulmonary artery 83 



Subclavian artery 87 



Basilar artery 91 



Vertebral artery 94 



Summary 99 



Description of plates 109 



Bibliography 110 



48 



