292 



ADVANCED PHYSIOLOGY 



cerebri is a prominent transverse band of fibres, the pons 

 Varolii, which connects the right half of the cerebellum with 



Optic 



Olfactory 



Cerebrum 



Medulla 



the left, going in 

 front of (ventral to) 

 the spinal cord as it 

 does so. Behind the 

 pons is the medulla. 

 The outer surface 

 of the brain in some 

 of the lower animals 

 is perfectly smooth, 

 but in man the cere- 

 brum and cerebellum 

 show many furrows 

 dipping into the sur- 

 face and separating 

 rounded ridges, 

 called convolutions. 

 If a number of dif- 

 ferent specimens of 

 the brain were ex- 

 amined, the main 

 convolutions would 

 be found to occur in 

 the same relative 

 positions in each. 

 The cerebellar con- 

 volutions are always 

 much narrower than 

 those of the cerebrum 

 and are more noticeably arranged in groups, with the ridges 



x The cranial nerves are numbered: 1, Olfactory; 2, Optic (at their 

 place of crossing [optic chiasma] the pituitary body is shown); 3, Oculo- 

 motor; 4, Patheticus; 5, Trigeminal; 6, Abducens; 7, Facial; 8, Auditory; 

 9, Glossopharyngeal; 10, Vagus; 11, Spinal accessory; 12, Hypoglossal. 



Crura 

 Cerebri 



Pons .. 

 Varolii 



Cerebellum 

 Spinal Cord 

 FIG. 147. THE BRAIN AS SEEN FROM BELOW 1 



Cerebrum 



Qray matter or Cortex 

 White matkr 



Cerebellum 



tfedulla 



FIG. 148. DIAGRAM 



Representing the divisions of the brain as lying in a 

 straight line and separated from each other and 

 showing the ventricles within. 



