MEMXGES 



67.') 



The Tentorium Cerebelli occupies the interval between the cerel^runi and 

 cerelx-lluiu. It presents for examination an upper surface, a lower surface, a free 

 or ctjncave 1 (order, and an attached or convex Ijorder. The upper surface is in 

 contact with the occipital and temporal lobes of the cerebrum, ami is strongly 

 convex ujjwards, forming a roof-like structure, to the ridge of which the base of 

 the falx cerel>ri is attached. This ridge also slopes upwards and forwards, so that 

 its highest i)oint is situated at the free l)ordcr. The under surface is in api)osi- 

 tion to the cerelxdlum. The free border Ijounds an opening usually described as 

 oval, l)ut which is more properly triangular with curved sides, the apex of the tri- 

 angle being turned backwards, and corresponding to the point where the veins of 

 Galen enter the straight sinus. This opening transmits the crura cerebri and the 

 superior peduncles of the cerebellum, these parts forming an isthmus connecting 

 the masses of brain suljstance above and below the tentorium ; the basilar artery 

 and the third pair of cranial nerves also jiass upwards through it. Followed 



Fig. 405. — The Cranium opened to shoav the Falx Cerebri, the Tentorium Cerebelli, 



AND the places WHERE THE CRANIAL NERVES PIERCE THE DURA MaTER. (Sappey. ) 



FOURTH SERVE 



THIRD NERVE 



Falx cerebri 



SECOSD SERVE 



Superior tonr/i- 

 tiidinal sinn.i 

 Inferior longi- 

 tudinal sinus 



Vtiiis of Galen 



Straight sinus 



Tentorium 

 cerebelli 



Lateral sinus — 



Superior 

 petrosal sinus 



Falx cerebelli 



.SEVESTlf ASD 

 EJiiHTH 

 SERVES 

 SISTH, TESTH, ASP 

 ELEVKSTH SERVES 



TWELFTH SERVE 

 SECOSD CERVICAL SERVE 



FIFTH 

 SERVE 



Middle 

 tn-ningeal 

 artery 

 Internal 

 carotid artery 



liigamentum denticulatum 



SERVE Inferior petrosal sinus 



forwards, the free border is seen to be attached to the anterior clinoid processes of 

 the sjthenoid V)one. The attached border follows the lateral sinus along the 

 occipital and ])arietal bones, and then corresponds to the sujierior petro.'sal sinus, 

 along the .superior l)order of the petrous portion of the temporal, and finally dips 

 under the free border, to be attached to the posterior clinoid process of the splienoid 

 bone. 



The Falx Cerebelli is a small ])rominent fold, which is ]>laced lietween the 

 cerebellar hemisjihcns. Its attached l>order corresponds to the occii)ital sinus 

 along the internal occipital crest. Above this it is attached for a short distance to 

 the under surface of the tentorium. Its free l)order looks upwards and forwards. 



The diaphragma sellae is a small, amiular. shelf-like fold of the dura mater 

 which root's in tlu- ]iitnitary fossa, leaving a small aperture in the centre, which 

 transmits the infun<libulum. 



The subdural space is a narrow lym]ih-space between the dura mater and 

 the arachnoid. It is occupied by a small i)oi-tion of the cerebro-spinal tiuid, the 



