

TEMPORAL LOBE. 153 



of the parietal. Behind and above it is continuous with part of the parietal lobe. 

 Behind, it is separated from the occipital lobe by the lateral occipital sulcus. It is 

 somewhat pyramidal in shape, having three surfaces, viz., lateral, superior and 

 inferior, the superior concealed within the fissure of Sylvius. The under surface 

 adjoins the limbic lobe, being separated from the hippocampal gyrus of that lobe by 

 the collateral fissure. The rounded apex of the pyramid is free, is directed forwards, 

 and lies underneath the orbital surface of the frontal lobe, from which it is separated 

 by the broad commencement of the Sylvian fissure. 



GYRI AND SULCI OF THE UPPER SURFACE. The upper surface of this lobe, 

 directed towards the insula and fronto-parietal operculum, is marked by two or three 

 transverse temporal gyri (Heschl). On the nearly smooth part of the surface in 

 front of these are three short gyri (m, fig. 108) separated by shallow sulci, which are 

 directed from the gyrus longus insulas towards the tip of the temporal lobe. 



SULCI AND GYRI OF THE LATERAL AND UNDER SURFACES. On these surfaces 

 there are four sulci with an antero-posterior direction. The first or superior 

 temporal sulcus, also termed from its relation to the Sylvian fissure the parallel- 

 fissure (fig. 101, /j), is an important furrow, appearing in the sixth month, and being 

 constant in the Primates. In many monkeys it is more extensive than in man. 

 nearly reaching the parieto-occipital fissure at the margin of the hemisphere. The 

 angular gyrus curves round its extremity. Both this and the second temporal turn 

 upwards as they poss back. The upturned extremity of the second sulcus may 

 appear as a continuation of the parallel, as in the brain here figured (fig. 101). The 

 fissure is sometimes interrupted by a small gyrus connecting the convolutions above 

 and below it. The second temporal sulcus (>) runs parallel to and below the 

 last, but is less constant in extent and direction. It is often interrupted by one or 

 more vertical connecting gyri. The postparietal gyrus curves round its extremity. 

 The third temporal sulcus ( / ;j ) is seen on the under surface of the lobe, extending 

 behind nearly to the occipital pole. It is often interrupted near its anterior and 

 posterior ends, and sometimes also about the middle by annectent gyri. In front it 

 generally fails to reach the extremity of the lobe, which forms a smooth " pole " from 

 which most of the sulci diverge. A fourth temporal sulcus ( 4 ) is formed by 

 the collateral fissure, which has already been noticed (p. 145) (figs. 101, 103). 



On the lateral surface of the lobe three convolutions can usually be distinguished. 

 The first or superior temporal gyrus (fig. 101, F-^ bounds the posterior limb of 

 the Sylvian fissure below, and is continuous behind with the supramarginal and to a 

 less extent with the angular convolution of the parietal lobe. The second temporal 

 gyrus (T^) is continuous with the angular and postparietal gyri. The third 

 temporal gyrus (T 3 ) is continuous with the occipital lobe by the annectent gyrus 

 which passes between the calcarine and lateral occipital sulci. On the under surface 

 of the lobe is the fourth temporal gyrus, lying between the third temporal 

 sulcus and the collateral fissure. The second and third gyri are convolutions of 

 some thickness, and are a good deal interrupted by transverse and oblique secondary 

 sulci. The fourth, which was formerly known as the first occipi to-temporal, is 

 narrower, and more sharply marked off by its bounding sulci. Its posterior part, 

 which has been termed the fusiform lobule, is usually described as belonging to the 

 occipital lobe (see previous page). Lastly, between the posterior part of the collateral 

 and the calcarine fissure is a fifth temporal gyrus, which was termed by Huschke 

 the lingual lobule, but it is better termed infracalcarim gyrus (subcalcarine gyrus of 

 Wilder). This is continuous in front with the hippocampal gyrus of the limbic 

 lobe (see below). It is joined by two deep annectent gyri, which pass across the 

 posterior calcarine fissure, connecting this gyrus with the cuneus (fig. 102, 2 and 3). 



The temporal lobe lies in the middle fossa of the skull, and its posterior part 

 overlies the tentoriuui. 



