416 



THE BRAIN 



The Sulci and Gyri of the Inferior Surface of the Occipital 

 Lobe. The posterior part of the collateral fissure extends 

 backwards from the temporal into the occipital lobe, separat- 

 ing the lingual gyms from the posterior part of the fusiform 

 gyrus, both of which enter into the formation of the inferior 

 surface of the occipital lobe (Figs. 138, 156). 



After the study of the fissures, sulci, and gyri of the supero- 

 lateral and inferior surfaces of the hemispheres is completed 



XX 



S.R.a. ' 



S.R./ 



Tz. 



FIG. 157. Fissures and Gyri on the Surface of the Insula. 

 (Eberstaller.) 



i, 2, and 3. Three short gyri on the frontal 



part of the insula. 



4 and 5. Two long gyri on parietal part. 

 S.R.a. Anterior part of circular sulcus. 

 S.R.-r. Superior part of circular sulcus. 

 S.R./. Inferior part of circular sulcus. 

 L. Limen insulae. 

 P. Pole of the insula. 



F. Orbital operculum (for the most part 



removed). 

 T. Temporal pole. 

 Ti. Superior temporal gyrus. 

 Ta. Middle temporal gyrus. 

 x.y. Transverse temporal gyri. 

 s.i. Sulcus centralis insulae. 

 s.a. Sulcus praecentralis insulae. 

 m. Gyri on deep surface of temporal pole. 



the dissector should separate the margins of the lateral fissure 

 from one another, and examine the insula, which lies under 

 cover of the boundaries of the fissure ; or if the brain is so 

 hardened that the margins of the fissure cannot be drawn 

 apart the dissector should cut away the portions of the frontal, 

 parietal, and temporal lobes which overlap and conceal the 

 insula. 



