REFLECTIONS OF THE DURA MATER. 395 



The nerves are few and small, and not easily traced. 

 Branches, however, are found going to the dura mater 

 from the fifth pair, and hranches from the sympathetic 

 accompany the meningeal artery. In consequence there- 

 fore of the paucity of the nerves, the sensibility of this 

 membrane is rather dull. 



Reflections of dura-mater. The principal of these reflec- 

 tions are the falx cerebri, tentorium, and falx cerebelli. 

 The falx cerebri (falx, a sickle) is a process, of a sickle-like 

 shape, from the dura mater along its median line. It is 

 situated between the hemispheres of the brain, which it 

 separates, and extends from the foramen ccecum and crista 

 galli of the sethmoid bone, proceeding by its superior bor- 

 der along the middle line of the frontal bone and the 

 sagittal suture of the parietal bones, back upon the upper 

 half of the vertical ridge of the occipital bone, to the ten- 

 torium, upon which it rests and with which it is continu- 

 ous; as it ascends it describes a curve, increasing in depth 

 as it proceeds upward, having its superior border broad 

 and convex, containing the superior longitudinal sinus, 

 while its inferior is sharp and concave, enclosing the infe- 

 rior longitudinal sinus. 



The tentorium is stretched horizontally across the inferior 

 part of the cranium, separating the cerebrum from the 

 cerebellum. It is seen by lifting the posterior lobes of the 

 cerebrum, and is connected by its convex border to the 

 transverse ridge and tubercle of the occipital bone, the 

 inferior posterior angle of the parietal, the superior ridge 

 of the petrous, and the clinoid processes of the sphenoid. 

 The tentorium is convex above and concave below, and 

 derives its name from its being arched in the centre like a 

 tent. Along its convex border are the two lateral sinuses, 

 and upon its median line is the straight sinus. At its 

 anterior part is a large oval foramen occupied by the pons 

 Varolii, crura cerebri, and the superior vermiform process 

 of the cerebellum. 



The falx cerebelli is situated below the tentorium, upon 

 the inferior occipital ridge, and separates the hemispheres 



