INFERIOR PETROSAL SINUSES. 



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the internal carotid artery, accompanied by several filaments of the 

 carotid plexus, and crossed by the sixth nerve ; and, in its external 

 wall, the third, fourth, and ophthalmic nerves. These structures are 

 separated from the blood flowing through the sinus, by the tubular 

 lining membrane. The cerebral veins from the under surface of the 

 anterior lobes, open into the cavernous sinuses. They communicate 

 by means of the ophthalmic with the facial veins, by the circular 

 sinus with each other, and by the superior petrosal with the lateral 

 sinuses. 



The Inferior petrosal sinuses are the continuations of the cavernous 

 sinuses backwards along the lower border of the petrous portion of the 



Fig-. 133.* 



Y 



temporal bone at each side of the base of the skull, to the foramina 

 lacera posteriora, where they terminate with the lateral sinuses in the 

 commencement of the internal jugular veins. 



* 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 petrosal sinus. 

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

 7 The internal jugular vein. 8. The foramen magnum, p. The occipital 

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



