40 



A MANUAL OF ANATOMY. 



The Palx Cerebelli. Fig. 10. 



This is the small ridge of dura placed between the two 

 lobes of the cerebellum and extending from the under sur- 

 face of the tentorium in the middle line to the posterior 

 margin of the foramen magnum. 



The Straight Sinus. Diags. I and 2. 



This will be found by slitting up the attachment of the falx 



cerebri to the tentorium. It is contained or formed by the 



diverging halves of the 

 falx at its tentorial at- 

 tachment. It extends 

 from the anterior (free) 

 margin of the tentorium, 

 where it receives the 

 inferior longitudinal 

 sinus and the vein of 

 Galen, backward to end 

 in the torcular Herophili, 

 or be continued into 

 one of the lateral (usually 

 the left) sinuses. 



The Lateral Sinuses. 

 Diags. i and 2. 

 Fig. 10. 



These run in the 

 attached margins of the 

 tentorium from the inter- 

 nal occipital protuber- 

 ance behind to the 



petrous portion of the temporal bone, where they turn down- 

 ward through the sigmoid groove of the temporal bone to 

 pass through the posterior compartment of the jugular fora- 

 men and terminate in the internal jugular vein, q. v. y page 92. 



Diag. a. A DIAGRAM OF THE SINUSES AT 

 THE BASE OF THE SKULL. (I.S.H.)i, Cavern- 

 ous. 2, Superior petrosal. 3, Inferior petrosal. 

 4, and 5, Lateral. 6, Circular. 7, Transverse, 

 (more of a plexus). 8, Communicating between 

 the lateral and 9, Occipital sinuses. 10, Foramen 

 magnum. 



