150 



SINUSES OF THE DURA MATER. 



Fig. 131. 



cross in an enlarge- 

 ment called Torcutar 

 Herophilif where it is 

 joined by other sinuses. 

 Inferior longitu- 

 dinal sinus* — This 

 is situated in the in- 

 ferior margin of the 

 falx cerebri ; it empties 

 into the straight sinus 

 at the anterior edge of 

 the tentorium. 



Straight, or Fourth 

 sinus.^ — It reaches 

 from the junction of 

 the superior longitu- 

 dinal sinus to the tor- 

 cular Herophili, in the 

 median line of the tentorium, where it is joined by the falx cerebri. 



Vence Galenic — These veins are in the velum inlerpositum ; they 

 frequently unite into a trunk called azygos, before entering the 

 straight sinus. 



Lateral sinuses}^ — These com- 

 mence at the torcular Herophili, 

 are oval -shaped channels, and pur- 

 sue a curved course over the occi- 

 pital, parietal, and temporal bones, 

 until they reach the posterior fora- 

 men lacerum, where they emerge, 

 and form the commencement of 

 the internal jugular vein. In their 

 course they receive blood from se- 

 veral other sinuses. (Fig. 132.) 



Cavernous sinuses,^ are venous 

 cells on either side of the sella 

 turcica, containing a spongy struc- 

 ture ; into them empty the ophthal- 

 mic veins,* and through them pass 

 the internal carotid artery and the 

 sixth nerve. 



Circular sinus.^ — It surrounds 

 the pituitary gland in the sella tur- 

 cica, and communicates upon each 

 side with the cavernous sinus. 

 Superior petrosal sinus.^ — This is a small sinus, running along 

 the edge of the petrous portion of the temporal bone, and reaches 

 from the cavernous to the lateral sinus. 



Fig. 132. 



