194 A MANUAL OF ANATOMY. 



The internal is continuous with the superior frontal 

 convolution, the anterior with the middle frontal, and the 

 posterior or external with the inferior frontal convolution. 



The internal convolution is grooved by the olfactory 

 sulcus, within which rests the olfactory nerve. 



The under surfaces of the temporal and occipital lobes 

 should be taken together, as there is no line separating 

 them. 



The fissures seen here are portions of the hippocampal 

 or dentate, the parieto-occipital, the calcarine, the collateral, 

 and the inferior temporal. This last is more often com- 

 posed of several short, indistinct grooves, which extend 

 anteroposteriorly along near the external borders of the 

 temporal and occipital lobes. External to the inferior 

 temporal sulcus is the inferior temporal convolution (ante- 

 riorly) and the inferior occipital (posteriorly). Between 

 the above sulcus and the collateral fissure lies the inferior 

 occipitotemporal, or simply the occipitotemporal convolu- 

 tion. Then between the collateral and the calcarine, 

 fissures is the superior occipitotemporal convolution, 

 which, as explained before, is described under the names of 

 the uncinate gyrus for the anterior part, and the Ungulate 

 convolution for the posterior portion. To see these convo- 

 lutions and sulci the cerebellum must be raised. 



The cerebral hemispheres will be found separated ante- 

 riorly and posteriorly by the great longitudinal fissure. 



By raising the temporal lobe the beginning of the Sylvian 

 fissure is found : it starts behind the frontal lobe in a de- 

 pressed portion of the base of the brain (anterior perforated 

 space). 



Projecting backward from the centre of the base of the 

 cerebrum, between the temporal lobes, are seen the two 

 rounded masses of fibres, which are called the legs of the 



