THE HYPOPHYSIS 401 



believed that only the anterior lobe of the hypophysis was 

 functionally active, but it is now known that the posterior lobe 

 also possesses an internal secretion. 



On each side, the hypophysis is related to the cavernous 

 sinus and the important structures which are contained in its 

 walls (p. 116), namely, the third, fourth, ophthalmic division 

 of the fifth, and the sixth cerebral nerves and the internal 

 carotid artery. Anteriorly, the hypophysis is related to the 



FIG. 141. Radiogram of Skull, showing a normal hypophyseal 

 (pituitary) fossa. (From KNOX'S Radiography.} 



optic chiasma (Fig. 8). These relations are of importance, 

 as the results of pressure upon them may be of great help in 

 the diagnosis of enlargement of the gland. In the majority 

 of cases of acromegaly in which the hypophysis has been 

 examined, it has been found to have undergone some patho- 

 logical change, frequently of the nature of tumour growth. 

 The optic chiasma is most commonly affected, and cases of 

 bitemporal hemianopia are usually due to this Cause ; crossed 

 hemianopia or binasal hemianopia may also occur. Affections 

 26 



