VEINS OF THE BKAIK 971 



basal vein (see below), which, as already stated, is a tributary of the great cerebral 

 vein. 



(&) The superficial cerebral veins are more numerous and of larger calibre 

 than the cerebral arteries. They lie upon the surface of the cerebrum, drain 

 blood from the cerebral cortex, and they are divisible into two sets, the superior 

 and the inferior. 



The superior cerebral veins, twelve or more in number, lie in the pia mater 

 and subarachnoid space on the upper and lateral aspect of the cerebral hemispheres. 

 They run upwards and medially, to the margin of the longitudinal fissure where 

 they receive tributaries from the medial surface of the hemisphere, and they 

 terminate in the superior sagittal sinus or in the lateral lacunar expansions of the 

 sinus. The anterior veins of this set are small and run transversely, but the 

 posterior are large and run obliquely forwards and medially ; they are embedded 

 for some distance in the wall of the sinus, and their orifices are directed forwards 

 against the blood stream. 



The inferior cerebral veins lie on the lower and lateral aspects of the cerebral 

 hemispheres ; they run downwards and medially, and terminate in the sinuses 

 which lie at the base of the skull viz., the cavernous, the superior petrosal, and 

 the transverse sinuses. One of these veins, the superficial middle cerebral vein 

 (O.T. superficial Sylvian), runs along the posterior horizontal branch and the stem of 

 the lateral fissure (Sylvius) to the cavernous sinus ; occasionally it is united by an 

 anastomotic loop, known as the great anastomotic vein (Trolard), with the superior 

 sagittal sinus, and sometimes by the inferior anastomotic vein with the transverse 

 sinus. 



The anterior cerebral vein of each side lies in the longitudinal fissure, and 

 accompanies the corresponding anterior cerebral artery ; it receives tributaries from 

 the corpus callosum and the gyrus cinguli. Turning downwards, round the 

 genu of the corpus callosum, it reaches the base of the brain, and terminates in the 

 basal vein. 



The deep middle vein (O.T. deep Sylvian) lies deeply in the lateral fissure 

 (Sylvius) ; it anastomoses freely with the superficial middle vein, receives tributaries 

 from the insula and the adjacent opercula, and terminates in the basal vein. 



The basal vein commences at the anterior perforated substance ; it is formed by 

 the union of the anterior cerebral vein with the deep middle vein and with the 

 inferior striate vein. Passing backwards round the pedunculus cerebri, it terminates 

 in the great cerebral vein (Galen). Its tributaries are derived from the tuber 

 cinereum, the corpus mamillare, the posterior perforated substance, the uncus, the 

 inferior cornu of the lateral ventricle, and the pedunculus cerebri. 



Veins of the Mid-brain. The veins of the mid-brain terminate for the most 

 part either in the great .cerebral vein (Galen) or in the basal veins. 



Cerebellar Veins. These veins also are divisible into two groups, the super- 

 ficial and the deep. The former are quite independent of and much more 

 numerous than the arteries. They form two sets, the superior and the inferior. 



The superior superficial cerebellar veins terminate in a single median or vermian 

 efferent vessel which is sometimes double, and in several lateral efferents. The 

 superior vermian vein runs anteriorly and ends in the great cerebral vein (Galen). 

 The lateral superior cerebellar veins terminate in the transverse sinuses or in 

 the superior petrosal sinuses. 



The inferior superficial cerebellar veins also form a small vermian and numerous 

 lateral efferents; the former runs backwards and joins either the straight sinus 

 or one of the transverse sinuses, and the latter end in the inferior petrosal and 

 occipital sinuses. 



The deep cerebellar veins issue from the substance of the cerebellum and 

 terminate in the superficial veins. 



Veins of the Pons. The deep veins from the substance of the pons pass 

 forwards to its anterior surface, where they become superficial, and, anastomosing 

 together, form a plexus which is drained by superior and inferior efferent veins. 

 The superior efferent veins join the basal vein ; the inferior efferent veins either 

 unite with the cerebellar veins, or they open into the superior petrosal sinus. 



