Till': ni.onn SUPPLY <>! rill'. ENCEPHALON 



879 



TlIK Hl.oOI) Sri'I'l.Y (IF THK I'ArKl'H.U.nN 



The double origin of the CODtmUOlU arterial system of tin- lir.'iin given l>y (lie col fluence of 

 tlic two ventral arteries and by tlic two internal carotid arteries together with the desci iption 

 of the general distribution of ihe dillerent cerebral, rnesencephalic, and cerebellar aiterie.- into 

 which the system i.^ divided, and the origin and IOUDM ol' tin- Oorreaponding veins, are lully dealt 

 with in Section V. Here attention may lie called briefly to the abundant and systematic internal 

 distribution of the terminal branches of t he system and their intimate arrangement for the actual 

 nourishment of the nervous tissues within. 



The general plan of the blood supply for the entire encephalon may be Mimmari-.ed as follows: 

 (1) At their origin the different arteries are so connected, directly or indirectly, that the blood 

 approaching the brain by way of the vertebral and internal ca rot id arteries is practically a common 

 supply for all the arteries of the encephalon, ami a given part of it may possibly pass into anyone 

 of I In 'in. (2) In the pia mater of each division of the encephalon the different arteries again become 

 connected with each other in a superficial, freely anastomosing plexu-. continuous throughout. 

 (3) From this plexus of the surface, naturally oompond in part of the trunks of the different arteries 

 themselves, arise branches which enter directly into the nervous substance and which break up into 

 twigs that are tiriiiinul; i.e.. twigs that do not anastomose with each other. (4) The arterial 

 capillary system arising from the terminal twigs passes over into venous capillaries which 

 converge to form corresponding venous twigs which in their turn pass to the surface and join 

 in forming a peripheral, anastomosing venous plexus superimposed upon the similar arterial 



l"i<;. 653. DIAGRAM SHOWING THE MANNER OF DISTRIBUTION OF THE CORTICAL AND CENTRAL 

 BRANCHES OF THE CEREBRAL ARTERIES. 



! arteries 



mil tlriii/f nrteriet - 

 cerebral artery 



C.ifli.lTE .\UCLEUS 

 TJIALAML'S 



ornr Ti: ti-r 



i>Eiih~tn:.\ TED 

 8VB8TANCK 



Internal itriale arteriet 



plexus. (.5) From this venous plexus arise the different veins of the encephalon which may or 



may not accompany the arteries tor a short distance, and which finally empty into the sinuses 

 in the cranial dura mater. These, likewise confluent, empty into the internal jugular veins. 

 The chorioid plexuses of the ventricles of the brain are modifications of the general anastomosing 

 peripheral plexuses. The chorioid plexuse, of the lateral and third ventricles are derived largely 

 from branches of the iirti-rui clmriniilin. which arises separately from the internal carotid artery. 



The blood supply of the cerebrum may he.-t be taken as an illustration of the general plan 

 of the blood-vascular system of the encephalon. The terminal or internal branches of the 

 surface plexus, derived from the posterior, middle, and anterior cerebral arteries, are arranged 

 into two groups, a central or ganglionic and a cortical group. The central or ganglionic 

 branches themselves form four groups in each hemisphere: 



(1) The nitlirii-nii-xiiil <iroii/> consists of terminal brandies from the plexus of the domain 

 of the anterior cerebral artery, which | ass through the medial part of the anterior perforated 

 substance and supply the head of the caudate nucleus, the septum pellucidum, the columns 

 of the fornix, anil the lamina terminalis. ' 



('21 The null -rn-lii/i nil (/rn>i]> consists of terminal hram'hes from the domain of the middle 

 cerebral artery. These pierce the anterior perforated substance in two sub-groups (a) the 

 internal and i/n the ( xternal striate arteries ilig. u.YK The internal striate arteries pass 

 through the segments of the globlls pallidus of the lenticular nucleus and through the internal 

 capsule, to both of which they give branches, and they terminate in the caudate nucleus and 

 thalamus. The external striate arteries are larger and more numerous. They pass upwards 



