274 



THE EDVELOPMENT OF THE VASCULAR SYSTEM 



Middle cerebral vein Posterior cerebral vein 



Sinus cavernosus 

 Anterior cerebral vein 



N. hypoglossus 

 V. capitis lateralis 



FIG. 283. Vein? of the head of a 9 mm. human embryo (after Mall). X 9. 



Auditory vesicle 

 Vena capitis medialis 

 Trigeminal nerve t 

 Ophthalmic vein 



Superior sagit- 

 tal sinus 



Confluence of the sinuses 



..,.. , Superior 



Primitive jugular sagittal 



vein 



Middle cerebral vein 



Posterior cerebral 



vein 



Anterior cerebral vein \ 

 Ophthalmic vein 

 Trigeminal nerve 



Vena capitis 

 1 lateralis 



Auditory vesicle 



Confluence of the 



sinuses \ 

 Superior 

 sagittal 

 sinus 



Trigeminal nerve 

 Ophthalmic vein 



Anterior cerebral vein 

 'Middle cerebral vein 

 | Auditory vesicle 



Straight sinus 



Confluence 

 of the sinuses 



B 



Inferior sagittal siww 



Great cerebral vein 

 Superior sagittal 



Superior 

 pelrosal 

 sinus 

 Trans- 

 verse 

 sinus 



Auditory vesicle 



Ophthalmic vein \ Inf. pelrosal sinus 

 Trigeminal nerve 



FIG. 284. Four diagrams showing the development of the veins of the head (after Mall) 

 A, At four weeks; B, at five weeks; C, at the beginning of the third month; D, from an older fetus. 



Posterior 

 cerebral 

 vein 

 Jugular 



vein 



Vena capitis 

 lateralis 



Anterior cere- 

 bral vein 

 Sphenopari- 



' ' inus 



