ENCEPHALON. 



Fig. 2. 



1. Encephalon. Under this term are included the contents of the 

 cranium, namely, the cerebrum or brain proper, the cerebellum or little 

 brain, and the medulla oblongata. These parts collectively have been 

 by some called brain. 



When we look at a section of the encephalon, 

 in its natural position, we find many distinct parts, 

 and the appearances of numerous and separate 

 organs. So various, indeed, are the prominences 

 and depressions observable on the dissection of the 

 brain, that it is generally esteemed one of the 

 most difficult subjects of anatomy ; yet, owing to 

 the attention paid to it in all ages, it is now one of 

 the structures best understood by the anatomist. 

 This complicated organ presents a striking illus- 

 tration of the truth, that the most accurate ana- 

 tomical knowledge does not necessarily teach the 

 function. The elevated actions, which the ence- 

 phalon has to execute, have, indeed, attracted a 

 large share of the attention of the physiologist, 

 too often, however, without any satisfactory result ; 

 yet it may, we think, be safely asserted, that we 

 have become better instructed regarding the uses 

 of particular parts of the brain, within the last 

 few years, than during the whole of the century 

 preceding. 



The encephalon being of extremely delicate 

 organization, and its functions easily deranged, it 

 was necessary that it should be securely lodged 

 and protected from injuries. Accordingly, it is 

 placed in a round, bony case ; and by an admira- 

 ble mechanism is defended against damage from 

 surrounding bodies. Amongst these guardian 

 agents or tutamina cerebri must be reckoned : 

 the hair of the head; the skin; muscles; pericra- 

 nium; bones of the skull ; the diploe separating the 

 two tables of which the bones are composed, and 

 the dura mater. 



It is not an easy matter to assign probable uses 

 for the hair on various parts of the body. On the 

 head, its function seems more readily appropria- 

 ble. It deadens the concussion, which the brain Anterior view of the Brain 

 would experience from the infliction of heavy 

 blows, and prevents the skin of the scalp from 

 being injured by the attrition of bodies, 

 tary service, the former of these uses has been 

 taken advantage of; and an arrangement, some- J^Jve^ s.pon^Vwoii?? 1 ?! 

 what similar to that which exists naturally on the Fourth pair of nerves. 10. 



I -i i i T -I i i TIT Lower portion of medulla 



head, has been adopted with regard to the helmet, oblongata. 11,11. Medulla 

 The metallic substance, of which the ancient and is^da ?! 

 modern helmets are formed, is readily thrown into 



and Spinal Marrow. 



1, 1. Hemispheres of the 

 T ... cerebrum. 2. Great middle 



In mill- fissure. 3. Cerebrum. 4. 





