1 1 6 Neurological Technique 



the arachnoidea to the pia mater. By way of these trabeculae 

 the blood vessels pass from the one membrane to the other. 

 Next, note the following ingrowths or processes of the dura 

 mater : 



1. The falx cerebri, extending into the fissura longitudinalis 

 cerebri. 



2. The tentorium cerebelli, extending between the cerebrum 

 and cerebellum. 



3. The falx cerebelli, a less extensive ingrowth occupying 

 the groove between the cerebellar hemispheres (the incisura 

 cerebelli). 



Do the membranes of different parts of the- surface vary in 

 thickness ? Along the mid-line on either side of the falx cere- 

 bri, look for granulationes archnoidales (Pacchonian bodies). 

 Are all three of the membranes of the encephalon thicker than 

 those of the medulla spinalis ? 



(b) Blood supply : 



I. Veins. — Note that the dura mater may be separated into 

 two layers. Between these layers, identify the following 

 sinuses : 



The large sinus transversus situated in the tentorium cere- 

 belli. At the mid-line this sinus is connected with the sinus 

 sagittalis superior which runs the entire length of the falx cere- 

 belli and falx cerebri. 



Also emptying into the sinus transversus are numerous 

 venae cerebelli superiores and inferiores. Emptying into the 

 sinus sagittalis superior, note the various venae cerebri superi- 

 ores. 



Remove the falx cerebri and, running along in its inferior 

 border, note the sinus sagittalis inferior. 



On the ventral aspect of the encephalon, lying in the groove 

 between cerebrum and cerebellum and emptying into the lateral 

 extremities of the sinus transversus, note the two sinus petrosi 

 superiores. 



Now remove the tentorium cerebelli and observe that the 

 sinus sagittalis inferior is a continuation of the sinus rectus 



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