VASCULAR DRAINAGE OF ENDOLYMPHATIC SAC 



/O 



an important part in its topography. This consists in the replace- 

 ment of the primary head vein by a more dorsally situated longi- 

 tudinal channel. The middle dural plexus instead of draining, as 



SIN. RECTUS 



SIN. SAGITTALIS SUP. 



PLEXUS ANT. 



SIN. TRANS. 



V. OPTHAL. 



SIN. CAVERNOSUS 



SIN. PETROS. INF. 



FORAMEN 

 JUGULARE 



Fig. 2 Profile reconstruction showing the topography of the membranous 

 labyrinth and endolymphatic appendage in a human fetus 50 mm. long (No. 

 96, Carnegie Collection). The endolymphatic sac is partly covered by the trans- 

 verse sinus, which with the other head veins is shown in solid black. Enlarged 

 about 4 diameters. 



formerly, into the primary head vein drains caudalward into the 

 posterior dural plexus. Soon afterward the anterior dural plexus, 

 in a similar manner, changes its direction of drainage and instead 

 of- continuing to drain into the cephalic end of the primary head 



