THE BRAIN 



I8 5 



Coverings 



the tongue ; and pharynx}. Their sensory fibres enable us to taste, while the 

 motor fibres supply the muscles of the pharynx. 



The tenth pair are termed pneumogastric nerves (Gr. pneuma, breath ; 

 and gaster, stomach). They are very important mixed nerves which send 

 fibres to the larynx, lungs, heart, stomach, and the liver. 



The eleventh pair are motor nerves which supply certain muscles of the 

 neck. 



The twelfth pair are motor nerves which supply fibres to the muscles of 

 the tongue. 



SUMMARY. 



( Inner, delicate, vascular. 

 \ Closely invests the brain. 

 I Follows all the convolutions. 

 Arachnoid. A serous membrane. 



Tough, fibrous. 



Outer surface rough, and in contact with 

 the skull. 



Inner surface smooth. 



Right and left hemispheres. 



Surface convoluted. 



Fills all upper portion of cranium. 



Grey matter outside. 



Right and left hemispheres. 



Surface drawn into folds. 



Fills occipital portion of cranium. 



Grey matter outside. 



Connects the brain with the cord. 



Grey matter inside. 

 I Chief seat of sensation. 



Cerebrum . i The organ of the will and voluntary motion. 

 I The seat of the intelligence. 



The seat of muscular sense (see page 193). 



Co-ordinates muscular movements. 



Governs the muscles of respiration and 

 deglutition. 



A conducting medium between the brain 

 and the cord. 



B 



pq 



Fia mater 



Dura mater - 



Cerebrum 



Cerebellum 



Medulla 



. Functions J Cerebellum 



Medulla 



Structure 



QUESTIONS ON LES.SON XXXI. 



1. Describe the general structure of the brain, and the manner in which it is 



protected. 



2. What are the chief divisions of the brain ? Describe the relative positions 



of each part, and point out their chief structural differences. 



3. Describe the structure and functions of the cerebrum. What would be the 



result of injury or disease in this portion of the brain ? 



4. What reasons have we for believing that the cerebrum is the seat of the 



intelligence ? 



5. Describe briefly the structure and functions of the cerebellum. What 



would be the result of the destruction of this organ ? 



6. Where is the medulla oblongata situated ? Describe its general form and 



structure. What would happen if this portion of the brain were 

 removed ? 



