///A' ///:.!/> AND .\1:CK. 



'37 



Two systems of circulation arc given off from the circle of Willis: (i) 

 77/i' ganglimoe; (2) the cortical. You have just seen the ganglionic or end 

 arteries entering the brain by the perforated spaces. The cortical arteries and 

 their veins form the woof of the pia mater, the \varpof\vhich is connective tissue. 



I. h'roin ;<'///!/ source docs tlic brain receive it.s blood .' 

 The brain is supplied with blood by the circle of Willis. 



OPTIC THALAMUS 



OPTIC TRACT 

 TUBER CINEREUM 



POSTERIOR PER- 

 FORATED SPACE 

 CORPUS OENICU- 

 LA TVM EXTERNUM 



CORPUS fiKxicu- 



LATUM INTERNVM 



PYRAMIDAL BODY 

 OLIVARY BODY 



ARCIFORM FIBRES 



FIRST CERVICAL NERVE 



ANTERO-LATERAL GROOVE 



OF SPINAL CORD 

 ANTERIOR COLUMN OF 



.s/V.V.l/. ' 



ISLAND OF REIL 

 PITUITARY BODY 



CORPORA 

 ALBICANTIA 



CRUS CEREBRI 



PONS I'.IROLII 



GREAT HORIZONTAL 



FISSURE 

 FLOCCULUS 



FORAMEN CAECUM 



SPINAL ACCESSORY 

 NER VE 



FIG. 92. SURFACE ORIGIN OK i UK CRANIAL NERVES. (After Allen Thomson. Quain.) 



2. //fti' is this circle formed / 



It is formed by an anastomosis between branches of the internal carotid and 

 vertebral arteries. 



3. Hffii' dues the internal carotid rcctcli the brain ? 



It comes through the carotid canal and sphenotic foramen, and gives off: (r) 

 The anterior cerebral ; (2) the middle cerebral ; (3) the posterior communi- 

 cating. 



4. Hoii< docs the vertebral artery reach the brain ? 



It passes through the foramina in the transverse processes of the cervical 

 vertebra: and the foramen magnum. It divides into the two posterior cerebral 

 arteries. 



5. How is the blood returned from the brain / 



The blood from the ganglionic system is returned to the straight sinus by 



