104 



HEAD AND NECK 



The Relation of the Arachnoideal Granulations to the Superior 

 Sagittal Sinus and the Lateral Lacunae. When the granulations project 

 themselves into the sinus or into the lateral lacunae, they push before them 

 a thin, continuous covering of the floor of the space, and when they project 

 still further and encroach upon the bones of the skull they are covered also 

 by a thin expansion of the roof of the space. 



Dissection. In order to expose the falx cercbri divide the 

 superior cerebral veins, on each side, and displace the upper 

 parts of the hemispheres of the brain laterally. 



Falx cerebri 



Inferior sagittal sinus 

 Superior sagittal 



Cavernous si 



Vena cerebri magna 



.Tentorium 



.Transverse sinus 



Falx cerebelli 

 Transverse sinus 

 Inferior petrosal sinus Superior petrosal sinus 



FIG. 33. Sagittal section through the Skull, a little to the left of the 

 median plane, to show the processes of Dura Mater. 



V. Trigeminal nerve. 

 VII. Facial nerve. 

 VIII. Acoustic nerve. 



IX. Glossopharyngeal nerve. 



X. Vagus nerve. 

 XI. Accessory nerve. 

 XII. Hypoglossal nerve. 



Falx Cerebri (Figs. 33, 34). The falx cerebri is a sickle- 

 shaped reduplication of the inner layer of the dura mater 

 which descends, in the median plane, between the two 

 cerebral hemispheres. Anteriorly, it is small, and it is 

 attached to the crista galli of the ethmoid bone. As it 

 passes backwards it increases in vertical extent, and the 

 lower border of its posterior portion is attached, in the 

 median plane, to the upper surface of the tentorium cerebelli. 

 The anterior part of the falx is frequently cribriform, and 

 is sometimes perforated by apertures to such an extent that 



