332 INFERIOR LONGITUDINAL SINUS. 



from the diploe, and near the posterior extremity of the sagittal 

 suture the parietal veins, from the pericranium and scalp. Examined 

 upon its interior, it presents numerous transverse fibrous bands, the 

 chordae Willisii, which are stretched across its inferior angle ; and 

 some small white granular masses, the glandular Pacchioni ; the 

 oblique openings of the cerebral veins, with their valve-like margin, 

 are also seen upon the walls of the sinus. 



The termination of the superior longitudinal sinus in the two 

 lateral sinuses forms a considerable dilatation, into which the straight 

 sinus opens from the front, and the occipital sinuses from below. 

 This dilatation is named the tarcular Herophili,* and is the point of 

 communication of six sinuses the superior longitudinal, two lateral, 

 two occipital, and the straight. 



Fig. 118.t 



The Inferior longitudinal sinus is situated in the free margin of the 

 falx cerebri ; it is cylindrical in form, and extends from near the 

 crista galli to the anterior border of the tentorium, where it termi- 

 nates in the straight sinus. It receives in its course several veins 

 from the falx. 



The Straight or fourth sinus is the sinus of the tentorium ; it is 

 situated at the line of union of the falx with the tentorium ; is 

 prismoid in form, and extends across the tentorium, from the termina- 



* Torcular (a press), from a supposition entertained by the older anatomists that the 

 columns of blood, coming in different directions, compressed each other at this point. 



t The sinuses of the upper and back part of the skull. 1. The superior longitudinal 

 sinus. 2, 2. The cerebral veins opening into the sinus from behind forwards. 3. The 

 falx cerebri. 4. The inferior longitudinal sinus. 5. The straight or fourth sinus. 6. 

 The yense Galcni. 7. The torcular Herophili. 8. The two lateral sinuses, with the 

 occipital sinuses between them. 9. The termination of the inferior petrosal sinus of 

 one side. 10. The dilatations corresponding with the jugular fossae. 11. The internal 

 jugular veins. 



