Fig. II. Convolutions of the Brain and Sutures of the Skull 



in the child. 



Fig. 12. Convolutions of the Brain and Sutures of the Skull 



in the Adult. 



Cunningham's Method of removing the Skull Bones, except narrow bars at the 

 sutures, affords an excellent method of shewing the relations of the Cerebral Convolutions to 

 the Cranial Sutures. (Skeletotopy of the Brain, Waldeyer.) It is advantageous to consider the 

 fissures and sulci rather than the convolutions. In the removal of the skull bones in the infant 

 it should be remembered-that they become attenuated at the regions farther away from their 

 ossific centres; this diminution in the thickness of the Bone is replaced by a corresponding 

 thickening of the Dura Mater and Pericranium. This close union of the fibrous skull-cap 

 checks the spreading of subdural and subperiosteal Haematomata within the limiting area of 

 any one bone. Moreover, it follows, that Bone and Dura Mater are removed in one piece 

 during this dissection in the new-born. In later childhood and adult life the bones are, as a 

 rule, easily separated from the dura mater, difficulties only occurring at the following points: 

 near the Superior Longitudinal Sinus because Pacchionian bodies may be present, and at the 

 Parietal Foramen (Santorini). The Mastoid Emissary Vein may be a point for dangerous 

 haemorrhage because of the proximity of the Lateral Sinus. The Emissary Veins favour the 

 spread of inflammation (cf. Erysipelas complicated by Meningitis). 



At the Sphenoparietal Sinus there is danger of Haemorrhage from laceration of the 

 Anterior Branch of the Middle Meningeal Artery which may be embedded in a partial or 

 complete canal near to it. (Cf. Fig. 32.) 



In connection with the position of the Sulci and Fissures it should be noted that in 

 the new-born (Fig. lo) the Fissure of Sylvius lies at a higher level than the Squamosal Suture, 

 and that the Central Fissure (Rolando) is placed more anteriorly than in the adult. In the 

 child (Fig. II) the squamous portion of the Temporal Bone grows upwards and the temporal 

 ridges become more definite (blue in the figure in order to distinguish them from the 

 sutures [r e d]). 



In the adult the Fossa of Sylvius corresponds closely to the Squamosal Suture. 

 (Cf. Fig. 19.) 



Accordingly, with certain individiual variations, the relation of the Fossa of Sylvius 

 to the skull bones gradually alters with the bony development. The most important central 

 convolutions, however, lie at all ages in the middle third of the Parietal Bone, being slightly 

 further forward in the new-born. To the surgeon interest is attached to the sutures, because 

 certain anthropometric markings are employed (Fig. 18). 



Nasion, at base of nose, and Inion, at external occipital protuberance, both points 

 are employed in connection with the determination of the upper extremity of the Central 

 Fissure (Rolando). 



Lambda, in middle line, where the Sagittal and Lambdoid Sutures meet, is employed 

 for the determination of the Paiieto-occipital Fissure. 



Obelion, a point above the former, less irregular in shape, corresponds to the Parietal 

 Foramen. 



Bregma, junction of Sagittal and Coronal Sutures, is at the anterior border of the 

 Parietal Bones. 



On the lateral aspect of the Skull, the Asterion, is the postero-inferior angle of the 

 Parietal Bone, where the lateral sinus turns downwards. 



Stephanion, the crossing of the coronal suture and the temporal ridges (near the 

 Spheno-parietal Sinus). 



Pterion, the point of meeting of the Sphenoid, Parietal and Temporal Bones ; this is 

 the site for ligature of the Anterior Branch of the Middle Meningeal Artery: underneath lies 

 the Fossa of Sylvius. 



