REMOVAL OF THE BRAIN 



119 



it anastomoses with the rami of the anterior division of the 

 middle meningeal artery. 



The accessory meningeal artery (O.T. small meningeal} is 

 somewhat inconstant ; it arises either directly from the 

 internal maxillary or from the middle meningeal, and 

 enters the cranium through the corresponding foramen ovale, 

 but it should not be looked for at the present stage, as it 

 is best examined along with the semilunar (O.T. Gasserian) 

 ganglion and the three divisions of the trigeminal nerve. 



The meningeal branches from the ascending pharyngeal arteries 

 are the terminal twigs of those vessels. They enter the 

 cranium through the lacerate and jugular foramina, and 



FIG. 40. i, Hypophysis ; 2, in median section ; 

 3, in horizontal section. (Schwalbe. ) 



a. Anterior lobe. 



b. Posterior lobe. 

 cm. Corpus mamillare. 



i. Tuber cinereum. 



ch. Optic chiasma in section. 



ro. Optic recess of the third ventricle. 

 o. Optic nerve. 



a'. Infundibulum, with projection from 

 anterior lobe upwards anterior 

 to it. 



through the hypoglossal canal (O.T. anterior condyloid 

 foramen). The branch which passes through the jugular 

 foramen is the largest. 



The meningeal branches of the occipital and vertebral arteries 

 are small, and are distributed in the posterior cranial fossa. 

 The former enter through the jugular, mastoid, and parietal 

 foramina, the latter through the foramen magnum. 



The meningeal veins may be regarded as being arranged in 

 two sets : one set consists of small channels which pour their 

 blood into the blood sinuses ; the other set is composed of 

 veins which accompany the meningeal arteries and carry 

 their blood to venous trunks on the exterior of the cranium. 



Dissection. Cut away the overhanging margins of the dia- 

 phragma sellae and carefully dislodge the hypophysis from the 

 fossa hypophyseos (pituitary fossa) of the sphenoid bone ; then, 



