THE CEREBRUM 



Organic lesions, sooner or later, lead to paralysis, which is 

 usually distributed over two regions, whose centres overlap 

 one another in the anterior central gyms. A pure mono- 

 plegia of cortical origin is extremely rare and, when it does 



FIG. 4. Lateral Aspect of Skull, showing the relations of important 

 structures to the surface. 



1. Zygomatic arch. 



2. Middle meningeal artery. 



3. Greater wing of sphenoid. 



4. Glabella. 



5. Temporal line. 



6. Anterior branch of middle meningeal 



artery. 



7. Central sulcus (of Rolando). 



8. Coronal suture. 



9. Lateral fissure, posterior ramus. 



io. Superior temporal sulcus. 

 n. Posterior branch of middle meningeal 

 artery. 



12. Line drawn from floor of orbit through 



centre of external acoustic meatus. 



13. External occipital protuberance. 



0*. Site for puncture of lateral ventricle, 

 o^. Site for puncture of inferior horn of 

 lateral ventricle. 



occur, it involves the lower limb. The condition is dia- 

 gnostic of a lesion in the posterior part of the medial surface 

 of the frontal lobe (Fig. 6). 



The upper extremity of the central sulcus corresponds on 

 the surface of the skull to a point which lies half an inch 

 behind the mid-point of the line joining the glabella (the 



