Fissure of Rolando 



45 



frontal and parietal above. Within the beginning of the fissure is the 

 island of Reil, The posterior border of the lesser wing of the sphenoid 

 is lodged in the fissure. 



The fissure of Rolando (central fissure] begins above near the 

 middle of the longi- 

 tudinal fissure, and 

 runs downwards and 

 forwards, almost to 

 the spot where the 

 Sylvian fissure bifur- 

 cates. It separates 

 the frontal from the 

 parietal lobe. 



The situation of 

 the fissure of Ro- 

 lando on the vertex 

 of the skull is \ in. 

 behind the middle of 

 a line passing from 

 the root of the nose 

 to the occipital protu- 

 berance, from which 

 it slopes downwards A > 

 and a little forwards. 



A simpler way of marking it on the shaven scalp is to draw a line 

 with an aniline pencil, from that part of the vertex which is directly 

 above the external auditory meatus, to the depression just in front of 

 the piece of cartilage (tragus) anterior to the meatus ; the fissure de- 

 scends along this line almost to the level of the Sylvian fissure (z/.z.). 

 The line thus drawn runs almost parallel with the coronal suture, 

 being about if in. behind it above, and i^ in. behind it below. But 

 the knowledge of the relative position of suture and fissure is of no 

 practical use to the surgeon, for the suture does not afford him a land- 

 mark when about to remove a tumour from the motor area ; the ani- 

 line mark upon the scalp is, however, of the greatest service. Though, 

 let it be remembered, the fissure of Rolando corresponds only to the 

 upper part of that mark. 



The ascending frontal convolution runs for the width of the finger 

 in front of this line, and the ascending parietal mounts behind it. 

 From the front of the former convolution it is easy to map out the three 

 horizontal frontal convolutions. 



The temporo-sphenoidal lobe is often the seat of abscess secondary 

 to suppurative otitis. It may be reached by the trephine applied two 

 inches above and behind the external auditory meatus. There are 

 more complicated ways of indicating the situation of this spot, but I 

 venture to say that they are not more precise. 



, c, trephine-crowns over fissure of Rolando, R ; F 3, Broca's 

 Region. After ERICHSEN. 



