NERVE SUPPLY TO PITUITARY GLAND 337 



NERVES TO THE ANTERIOR LOBE 



The key to the nerve supply of the pituitary body is the ar- 

 terial supply to this organ. In a recent publication from this 

 laboratory, it was shown (11) that the anterior lobe received an 

 extensive blood supply from a large number of minute vessels, 

 most of which, even when injected, were beyond the range of 

 naked vision. These vessels radiate from the Willisian circle to 

 the hypophyseal stalk like spokes to the hub of a wheel. The 

 majority of these branches are from the anterior and posterior 

 communicating arteries. The network of sympathetic nerves 

 comprising the carotid plexus is continuous along the three main 

 branches which result from its trifurcation. The distribution, 

 however, is very uneven. A few fibers -continue along the ante- 

 rior and middle cerebral arteries for a short distance but the great 

 majority are found on the two communicating arteries which 

 supply the hypophysis; the posterior communicating artery is 

 particulary well supplied. From these extensions of the carotid 

 plexus numerous filaments are given off and pass along the 

 blood vessels to the stalk of the hypophysis, from which they 

 delve into the substance of the anterior lobe and are lost to 

 view. Some arterial branches have as many as three or even 

 four small filaments, the majority, however, only one or two. 

 The course of the fibers is fairly direct and very few branches 

 are given off. These filaments frequently entwine the vessels 

 but no minute plexuses or anastomoses are visible after leaving 

 the plexus on the main trunks. No nerves have been observed 

 on the external surface of the anterior lobe. All nerves going 

 to the hypophysis are in contact with the sheaths of minute 

 blood vessels. On reaching the stalk it is of course impossible 

 to trace this relation further. Their distribution in the gland has 

 not been observed. 



