512 



DISSECTION OF THE HEAD. 



difference 

 on two 



and tribu- 

 taries. 



occipital, parietal and temporal bones, to the jugular foramen, 

 where it ends in the internal jugular vein. The sinus of the right 

 side is generally larger than the left, and begins at the torcular 

 Herophili behind, forming, usually, the continuation of the superior 

 longitudinal sinus. The left lateral sinus is mainly prolonged 

 from the ending of the straight sinus, but it is also joined by a 

 branch from the lower end of the superior longitudinal sinus, which 

 crosses obliquely in front of the occipital protuberance. In some 

 cases this arrangement is reversed, so that the torcular Herophili 

 and the larger lateral sinus are placed on the left side ; and 

 occasionally the torcular Herophili forms a common place of the 

 meeting (confluence) of the superior longitudinal, the straight and 

 the two lateral sinuses. 



The lateral sinus is joined by some cerebral and cerebellar veins, 



FIG. 187. SOME OF THE VENOUS SINUSES OP THE SKULL. 



a. Torcular Herophili. 



b. Superior, c. Inferior longi- 

 tudinal sinus. 



d. Straight sinus. 



e. Lateral sinus. 

 g. Occipital sinus. 

 /. Superior, and h. Inferior 

 petrosal sinus. 



Subdivision 

 of the 

 jugular 

 foramen. 



Dissection. 



and, opposite the upper edge of the petrous portion of the temporal 

 bone, by the superior petrosal sinus. It communicates with the 

 occipital veins through the mastoid foramen, and often with the 

 deep veins of the neck through the posterior condylar foramen. 



The jugular foramen is divided into three compartments by 

 fibrous bands. Through the posterior opening the lateral sinus 

 passes ; through the anterior the inferior petrosal sinus : and 

 through the central one the ninth, tenth, and eleventh nerves. 



Dissection. The dissectors should first examine the cavernous 

 sinus on the left side. Cut through the dura mater by the side of 

 the body of the sphenoid bone from the anterior to the posterior 

 clinoid process, and internal to the position of the third nerve ; 

 behind the clinoid process, let the knife be directed inwards for 

 about half the width of the basilar part of the occipital bone. By 



