378 



CEREBRUM. 



6. Cavernous sinuses, which are placed at the sides of the 

 sella turcica, surrounding the carotid arteries and the sixth pair 



Fig. 186.* 



of nerves, and receive blood 

 from the circular sinuses the oph- 

 thalmic veins and several con- 

 tiguous parts, and discharge it into 

 the 



7. Inferior petrous sinuses, 

 which are placed at the bases of 

 the partes petrosae, and discharge 

 this blood into the ends of the 

 lateral sinuses. To these should 

 be added 



8. The superior petrous sinu- 

 ses, which are situated on the up- 

 per edges of the petrous bones. 

 They communicate both with the 

 lateral and the cavernous sinuses, 

 and receive some small veins from 

 the adjacent parts. 



There are also several small sinuses near the great occi- 

 pital foramen, which communicate with the lateral sinuses, 

 and also with the vertebral veins. They are called occipital 

 sinuses. 



The brain or the whole of the soft substance contained within 

 these membranes, is composed of four portions, viz., cerebrum) 

 cerebellum, tuber annulare or pons Varolii, and medulla oblon- 

 gata. 



Of the Cerebrum. 



The cerebrum completely fills the upper part of the cavity of 

 the cranium. It has some resemblance to the half of an egg, 

 which has been divided horizontally ; and is composed of two 



* The sinuses of the base of the skull. 1. The ophthalmic veins. 2. The 

 cavernous sinus of one side. 3. The circular sinus ; the figure occupies the 

 position of the pituitary gland in the sella turcica. 4. The inferior petrous 

 sinus. 5. The transverse or anterior occipital sinus. 6. The superior petrous 

 sinus. 7. The internal jugular vein. 8. The foramen magnum. 9. The occi- 

 pital sinuses. 10. The torcular Herophili. 11, 11. The lateral sinuses. 



