10 Development of Blood- Vessels of Human Brain 



tions the veins undergo. The subject is, however, simplified to a great 

 extent b}^ the excellent studies of Hochstetter and his pupils, Salzer, and 

 Groszer and Brezina, who have unraveled many of t]ie tangles of the 

 anterior cardinal vein while it is being transformed into the brain 

 sinuses. The study of the development of the veins of the head of 

 the guinea-pig by Salzer ' is especially of value to me, for it takes up a 

 number of points which would be difficult to interpret properly from 

 my material. 



It is generally believed since the time of Luschka * that the blood from 

 the veins of the brain leaves the embryonic skull through a foramen in 

 front of the temporal bone — the foramen jugulare spurium — and emp- 

 ties into the external jugular vein. A secondary communication is 

 formed with the internal jugular vein, which in man and in monkeys 

 is the only outlet of the brain sinuses, both communications remaining 

 open to a greater or less degree in many vertebrates. Luschka also 

 found a human skull with a foramen jugulare spurium present be- 

 tween the temporal bone and the glenoid fossa. This opening is referred 

 to frequently in the various text-books on anatomy,^ and it is explained 

 by stating that it is the remains of a channel through which the blood 

 poured in the foetus. This explanation may be correct as far as it goes, 

 but when it is asserted that the brain sinuses at first communicate with 

 the external jugular vein through the foramen spurium and later with 

 the internal jugular vein, a conclusion is drawn which the facts do not 

 warrant. Although Salzer showed conclusively that the internal jugu- 

 lar vein receives all the blood from the brain from the very earliest 

 stage, and that the connection with the external jugular is of much later 

 formation, Luschka's statement is still retained in the text-books."* 

 While Salzer corrected the erroneous interpretation of Luschka, he also 

 discovered that in the embryo the veins first leave the embryonic skull 

 through a canal near the seventh nerve, and then emptied into the internal 

 jugular vein. All this takes place long before there is a trace of an 

 external jugular vein present, so the idea of Luschka that the external 

 jugular vein is the primary vein for the blood from the brain is un- 

 tenable, and should be removed from the text-books as soon as jjossible. 



Salzer^s work shows that the anterior cardinal veins of mammals are 

 placed on either side of the chorda ventral to the brain between the 



^Salzer: Morph. Jahrbuch, XXIII, 1895. 

 * Luschka: Denkschriften der Wiener Akademie, XX, 1862. 

 ^ See for instance Cunningham's Anatomy, p. 116. 

 "Cunningham's Anatomy, Figs. 603 to 606. 



