100 



ZOOLOGY. 



10 

 11 

 13 



9 

 25 



marrow following it, may be seen 

 proceeding outwards the spinal 

 nerves. No nerves come from or go 

 to the cerebrum proper, unless it 

 be the olfactory. Where the nerves 

 leave the spinal marrow to proceed 

 to the pectoral extremities, the organ 

 is usually enlarged ; and the same 

 occurs, but not so distinctly, lower 

 down, where the nerves leave to 

 proceed to the pelvic extremities. 

 In man, the spinal marrow descends 

 only as low as the second lumbar 

 vertebra, terminating in a fine 

 thread-like body, by which it is 

 attached to the lower part of the 

 column. The inferior portion of the 



* The cerebrospinal axis seen anteriorly : 

 the nerves have been cut through at a short 

 distance from their origin or central termi- 

 33 nation : a, the cerebrum ; b, anterior lobe 

 of the left hemisphere of the brain ; c, middle 

 lobe ; d, posterior lobe, almost concealed by 

 the cerebellum ; e, the cerebellum ; f t the 

 medulla oblongata or bulb ; 1, first, or ol- 

 factory pair of nerves; 2, second pair, or 

 , optic ; 3, third pair, or motores oculorum , 

 4, fourth pair, or pathetic ; 5, the facial, or 

 i fifth pair : 6, sixth pair, or abducentes ; 

 7, nerves of the seventh pair, or facial ; also 

 the acoustic or portio mollis, by some called 

 the auditory, and viewed as a division of the 

 k seventh; others call them the eighth pair; 

 9, the glosso-pharyngeal nerves, called the 

 ninth pair by some, by others the anterior 

 division of the eighth pair ; 10, tfce pneumo- 

 gastric, by some included in the eighth pair, 

 by others called the tenth pair; 11, nerves 

 of the eleventh and "twelfth pairs, the first 

 being viewed by some as a division of the 

 / eighth pair, and called spinal accessory; 



TV /. n v, i t- ne latter, called by some the ninth, by 

 Fig. 66. Cerebro-spmalAxis.* others the twelfth, is the motor nerve of 

 the tongue ; 13, nerves of the thirteenth pair, 



or sub-occipital; 14, 15, 16, the first, second, and third pairs of cervical 

 nerves; g, cervical nerves forming the brachial plexus; 25, one of the 

 pairs of nerves of the dorsal portion of the spinal marrow ; 33, one of the 

 pairs of lumbar nerves ; h, lumbar and sacral nerves forming the plexus 

 whence come the nerves of the lower extremities ; i andj, termination of the 

 spinal marrow, called cauda equina ; k, great sciatic nerve proceeding to the 

 lower extremities. 



