436 Anatomy Applied to Medicine and Surgery. 



front of the auditory meatus and the other along the pos- 

 terior border of the mastoid process. From the junction 

 of this latter or posterior perpendicular line with the 

 longitudinal fissure, draw a line downwards and forwards 

 to the junction of the anterior perpendicular with the line 

 for the Sylvian fissure. This represents the fissure of 

 Rolando. Another method for locating the fissure of Ro- 

 lando is to draw a line from a point half an inch behind 

 the centre of the longitudinal fissure, downwards and for- 

 wards, for about three and three-eighths inches to ter- 

 minate about half an inch behind the ascending limb of the 

 fissure of Sylvius. Parieto-occipital fissure. Extend the 

 line for the horizontal limb of the fissure of Sylvius back- 

 wards to join the longitudinal fissure. The posterior half 

 or three-quarters of an inch of this line represents the 

 parieto-occipital fissure. This fissure is situated about 

 half an inch in front of the lambda, i.e., about two and a 

 half inches above the external occipital protuberance. 

 The superior frontal fissure is indicated by a line drawn 

 backwards from the supra-orbital notch to terminate 

 about three-quarters of an inch from the upper end of the 

 fissure of Rolando, while the inferior frontal fissure fol- 

 lows the course of the temporal ridge from the external 

 angular process to within three-quarters of an inch of the 

 fissure of Rolando. The precentral fissure lies parallel 

 with and about three-quarters of an inch in front of the 

 lower two-thirds of the fissure of Rolando. The intra- 

 parietal fissure begins about half an inch behind the junc- 

 tion of the middle and lower thirds of the fissure of Rolan- 

 do ; passes upwards parallel to the latter and then curves 

 backwards, midway between the longitudinal fissure and 

 the parietal eminence, to end about midway between the 

 lambda and this eminence. 



The superior tempero-sphenoidal fissure is represented 

 bv a line drawn parallel with and one inch below the line 



