414 THE BRAIN 



Sulcus Temporalis Inferior. The inferior temporal sulcus 

 is below and lateral to the collateral fissure. 



The Gyri of the Inferior Surface of the Temporal Lobe are 

 the hippocampal gyrus, the lingual gyrus, the fusiform gyrus, 

 and a part of the inferior temporal gyrus. 



Gyrus Hippocampi. The hippocampal gyrus is bounded 

 by the rhinal and collateral fissures, infero-laterally, and the 

 chorioidal fissure, supero-medially. The posterior end of 

 the hippocampal gyrus is continuous, below the stem of the 

 calcarine fissure, with the anterior part of the lingual gyrus, 

 and, in front of the anterior end of the calcarine fissure, it 

 is connected by means of a narrow bridge, called the isthmus, 

 with the posterior part of the gyrus cinguli, which embraces 

 the corpus callosum, and which forms, with the isthmus and 

 the hippocampal gyrus, a continuous fold of the cortex termed 

 the gyrus fornicatus. The anterior end of the hippocampal 

 gyrus is turned upwards and backwards, and is called the 

 uncus (Fig. 138). 



If the upper or medial border of the hippocampal gyrus, 

 behind the uncus, is displaced downwards a vertically notched 

 ridge of grey matter will be brought into view; it is the fascia 

 dentata, and it will be seen to much better advantage when 

 the inferior cornu of the lateral ventricle is studied. The 

 portion of the hippocampal gyrus which lies above and medial 

 to the rhinal fissure, including the uncus, is the piriform area, 

 and it is closely associated with the sensation of smell. The 

 more posterior part of the hippocampal gyrus forms the para- 

 dentate area (Fig. 156). 



Gyrus Lingualis. The portion of the lingual gyrus which 

 appears on the inferior surface of the temporal lobe lies be- 

 tween the stem of the calcarine fissure and the posterior part 

 of the collateral fissure (Figs. 138, 159). It is continuous 

 anteriorly with the hippocampal gyrus, and, posteriorly, its 

 upper part crosses the medial occipital border of the hemi- 

 sphere and forms part of the medial surface of the occipital 

 lobe. It constitutes a portion of the striate area or area of 

 vision. 



Gyrus Fusiformis. The fusiform gyrus lies between the 

 collateral fissure and the inferior temporal sulcus. It is con- 

 tinued posteriorly to the inferior surface of the occipital lobe. 



Gyrus Temporalis Inferior. Only a part of the inferior 

 temporal gyrus appears on the inferior surface of the temporal 



