422 THE BRAIN 



Gyrus Frontalis Superior. The superior frontal gyms has 

 been seen already on the supero-lateral surface of the hemi- 

 sphere (p. 406). It forms that part of the medial surface 

 which lies between the sulcus cinguli and the supero-medial 

 border, and anterior to the upper end of the anterior central 

 gyrus. 



On its antero-inferior part are two or three secondary gyri 

 which run antero posteriorly or forwards and slightly upwards ; 

 they are known as the rostral gyri. The posterior end of the 

 medial aspect of the superior frontal gyrus is separated from 

 the upper end of the anterior central gyrus by an offshoot 

 from the sulcus cinguli. 



Lobulus Paracentralis. The paracentral lobule corresponds 

 in position with the upper ends of the anterior and posterior 

 central gyri. It is bounded, posteriorly, by the upturned end 

 of the sulcus cinguli ; anteriorly, by an offset from the sulcus 

 cinguli. Its frontal portion is part of the motor area of the 

 cerebrum. 



Pracuneus. The precuneus is the medial part of the 

 superior parietal lobule of the supero-lateral surface (p. 410). 

 It is bounded, behind, by the parieto-occipital fissure ; in 

 front, by the upturned end of the sulcus cinguli ; below, by 

 the sulcus subparietalis ; and, above, by the supero-medial 

 border of the hemisphere. 



Cuneus. The cuneus forms the greater part of the medial 

 surface of the occipital lobe. It is bounded, anteriorly, by 

 the parieto-occipital fissure ; below, by the calcarine fissure ; 

 and, above and behind, by the supero-medial border of the 

 hemisphere. 



Gyrus Lingualis. The lingual gyrus forms the lowest 

 part of the medial surface of the occipital lobe. On that 

 surface it lies between the calcarine fissure and the medial 

 occipital border, which separates the medial from the posterior 

 part of the inferior surface of the hemisphere. Anteriorly, 

 it crosses the medial occipital border and passes to the 

 inferior surface, where it has already been seen (Fig. 138). 



After the study of the fissures, sulci, and gyri of the medial 

 surface of the hemisphere is completed, the dissector must 

 remove the upper part of the left hemisphere above the level 

 of the corpus callosum and anterior to the parieto-occipital 

 fissure, but the fissure itself, and the part of the brain behind 

 it, should be left intact so that a repeated study of the 



