VESALIUS. 79 



is occupied with a minute description of the build of the 

 human body its bones, cartilages, ligaments, and muscles. 

 It may have been owing to the thorough acquaintance 

 which Vesalius showed with these parts that his detractors 

 pretended afterwards that he only understood superficial 

 injuries. But other branches of anatomy are fully dealt 

 with. The veins and arteries are described in the third 

 book, and the nerves in the fourth ; the organs of nutri- 

 tion and reproduction are treated of in the next ; while 

 the remaining two books are devoted to descriptions of 

 the heart and brain. 



Vesalius gives a good account of the sphenoid bone, 

 with its large and small wings and its pterygoid processes ; 

 and he accurately describes the vestibule in the interior 

 of the temporal bone. He shows the sternum to consist, 

 in the adult, of three parts and the sacrum of five or six. 

 He discovered the valve which guards the foramen ovale 

 in the foetus ; and he not only verified the observation of 

 Etienne as to the valve-like fold guarding the entrance of 

 each hepatic vein into the inferior vena cava, but he also 

 fully described the vena azygos. He observed, too, the 

 canal which passes in the foetus between the umbilical 

 vein and vena cava, and which has since been known 

 as the ductus venosus. He was the first to study and 

 describe the mediastinum, correcting the error of the 

 ancients, who believed that this duplicature of the pleura 

 contained a portion of the lungs. He described the 



