FALX MAJOR. TENTORIUM. FALX MINOR. 375 



runs along the upper and nnidclle part of the head ; adhering 

 first to the frontal, then to the joining of the parietal, and after- 

 wards to the middle of the occipital bone. 



In its passage it becomes gradually broader, and terminates 

 behind, in the middle of the tentorium. 



It runs from before backwards in a straight direction, and 

 has some resemblance in shape to a sickle or scythe, placed with 

 its edge downwards ; from which circumstance it has obtained 

 the name o{ falx. 



After extending backwards as far as the centre of the crucial 

 ridge, on the internal surface of the occipital bone, it extends 

 to each side, and forms a horizontal partition, which partially 

 divides the lower part of the cavity from the upper: but it does 

 not extend so far forward, as to separate, completely, the mass 

 which is under it, or the cerebellum, from the upper part of the 

 brain, or cerebrum. 



This horizontal membrane is called the tentorium and also 

 the transverse septum : it is connected behind to the inner 

 transverse ridges and grooves of the occipital bone, and, at the 

 fore and outer edges, to the ridges and great angles of the tem- 

 poral bones, and terminates at the posterior clinoid process of 

 the sphenoid bone. 



Between the inner edge of the tentorium and the posterior 

 clinoid process of the sphenoid bone, there is a large notch, or 

 oval foramen, where the brain and cerebellum are united, or 

 where the tnher annulare is chiefly situated which unites them. 



The tentorium keeps the falx tense, and forms a floor or vault 

 over the cerebellum, which prevents the cerebrum from pressing 

 upon it. 



The falx minor, or septum cerebelli, is placed between the 

 lobes of the cerebellum. It descends from the under and back 

 part of the falx in the middle of the tentorium, adheres to the 

 inferior longitudinal spine of the os occipitis, and terminates 

 insensibly at the edge of the foramen magnum of that bone. 



Besides the process of the dura mater already described, 

 there are four of inferior consideration ; two of which are situ- 

 ated at the sides of the sella turcica, and two at the edges of 

 the foramina lacera. 



