SURGICAL ANATOMY OF THE CRANIUM. 



19 



which is of importance. The sagittal suture, extending 

 from the root of the nose to the occiput, is crossed at 

 right angles by the coronal ; at the point of intersection 

 of these sutures is the anterior and larger fontanelle. 

 At the point where the lambdoidal suture crosses the 

 sagittal is the posterior fontanelle, generally closed at 

 birth, and recognizable by the peculiar convergence of 

 the three sutures. Hernia cerebri is the result of in- 

 complete closure of these spaces, which, however, are 

 generally ossified by the fourth year. 



FIG. 1. 



Diagram of structures to be avoided in use of trephine. 1, 2, 3. Branches of 

 middle meningeal artery. 4. Lateral sinus. 5. Superior longitudinal sinus. 



Fracture of the base of the skull by " contre-coup " is 

 denied by some, on the ground that the shock is resisted 

 by the cranium, and that the results of such shocks, as 

 in the case of architectural arches, are lost upon its sup- 

 porting pillars, which, in the frontal region, are the 

 malar and sphenoid bones, in the parietal the temporal 



