262 



THE NERVOUS SYSTEM 



THE SPINAL 

 CORD . 



Reflex action 



Position 



Coats 



Structure 



i In the spinal canal formed by the vertebral 

 I column. 

 f About eighteen inches. 

 Length . j Extends from the medulla oblongata to the first 



L lumbar vertebra. 

 Thickness About one-third of an inch. 



Pia mater delicate, vascular. 



Arachnoid serous, forming a loose bag. 



Dura mater tough, fibrous. 



(A layer of fatty tissue lies between the dura 



mater and the bony canal.) 

 Gray matter internal. 

 White matter external. 

 Anterior fissure. 



Posterior fissure deeper and narrower. 

 Central canal microscopic, 

 f Thirty-one pairs between the vertebrae. 

 I Crowded at the lower extremity of the cord 

 Nerves . . J \ cauda equina. 



Each trunk formed by the union of two roots. 



. ( Anterior motor. 

 Ro ts 1 Posterior -sensory. 

 f Conduction of impressions. 

 I A centre for reflex action (gray matter). 

 j Sensory fibres cross as they enter the cord. 

 I Motor fibres cross in the medulla oblongata. 

 f A disturbed condition of sensory fibres 



j Conducted to a nerve centre 

 { Reflected by the nerve centre along motor fibres to their 



terminations in muscles 

 I Muscular contraction. 



Functions 



QUESTIONS FOR TOPICAL REVIEW 



PAGE 



1. State fully what is meant by the term vegetative function 217 



2. To what does man owe his position as the head of the animal creation ? 218 



3. What can you state on the subject of special organs for separate 



functions ? 219 



4. Describe, as fully as you can, the structure of the nervous system. 218, 219 



5. Describe the brain, its location, size, shape, and structure 219-222 



6. Describe the brain proper, or cerebrum 222, 223 



7. Describe the little brain, or cerebellum 224, 225 



8. Describe the spinal cord 227, 228 



9. What are the spinal nerves, and how are they arranged ? 228 



10. What is the character and substance of their tissues ? 228, 229 



11. State and illustrate how the nerve-fibres perform their office 229, 230 



12. Describe the sympathetic system of nerves 230, 231 



13. State the properties of nervous tissue, and illustrate 231-233 



14. Explain the functions of the nerves 233 



15. What is meant by transient paralysis of a nerve ? Illustrate 234, 235 



16. What can you state of the rate of message-motion along a nerve?. . 235 



