402 THE DUCTLESS GLANDS 



of the third, fourth and sixth nerves, or of combinations of 

 these nerves, especially when the paralysis is bilateral, should, 

 in the absence of basal meningitis, suggest the possibility of 

 enlargement of the hypophysis. 



Inferiorly, a thin plate of bone separates the hypophysis 

 from the sphenoidal air sinuses (Fig. 114), and, when the gland 



FIG. 142. A much enlarged Hypophyseal Fossa, caused by a tumour 

 of the Hypophysis (pituitary body). (From a Radiograph taken 

 by Dr. S. G. SCOTT.) 



enlarges, this plate becomes so thin that it can easily be 

 removed during the operation of excision of the gland. The 

 sphenoidal sinuses act as a convenient landmark in lateral 

 radiograms of the skull, and the hypophyseal fossa can 

 usually be made out without great difficulty. In those cases 

 in which the optic chiasma is affected, an increase in the 

 antero-posterior extent of the fossa may be expected, but when 

 the tumour grows in a lateral direction, no sign of alteration 

 may be found in radiograms of the skull. 



