372 CEREBRO-SPINAL NERVES. 



this, is the pneumogastric nerve, or par vagum (10), which 

 supplies the lungs and air-passages, and also the heart and 

 stomach. Below this, again, is the hypoglossal nerve (11), 

 which gives motion to the tongue j at 12 is a nerve termed 

 the spinal accessory, which is concerned in the acts of respira- 

 tion; and at 13 and 14 are two of the regular spinal nerves. 

 The termination of all these nerves is either in that prolonga- 

 tion of the Spinal Cord into the cavity of the skull, which is 

 termed the Medulla Oblongata (fig. 197, /'), or in the Sensory 

 Ganglia which are closely connected with the upper part of 

 this prolongation. Although some of them seem to pass 

 directly into the Cerebrum, it is very doubtful if such is really 

 the case. 



460. A general connected view of the Brain and Spinal 

 Cord is given in fig. 197 ; which represents the front of the 

 latter, with the Brain a turned back, so as to expose its 

 under side. At 5 is seen its anterior lobe ; at c its middle 

 lobe ; and its posterior lobe d is almost entirely concealed by 

 the Cerebellum e. At /' is shown the Medulla Oblongata, 

 or upper end of the Spinal Cord ff. The brachial plexus 

 is seen at g, formed by the nerves that originate in the cervical 

 region of the cord ; at h is the lumbar plexus formed by the 

 nerves of the lumbar portion ; and at k is the sacral plexus 

 formed by the sacral nerves. The spinal cord terminates at 

 its lower extremity in a bundle of nerves /, to which the name 

 cauda equina is given, from its resemblance to a horse's tail. 

 The various pairs of nerves from 1 to 14 are the same as in 

 the preceding description; 15 and 16 are nerves from the 

 upper part of the cervical region ; 25, a pair from the dorsal 

 region ; and 33, a pair from the lumbar region. All these 

 spinal nerves find their way out through apertures in the 

 vertebral column, which are formed by a union of two notches, 

 one in each of the adjoining vertebrae. 



461. The system of nerves which has been now described 

 is termed the Cerebro-Spinal ; but it is not the only set of 

 nerves and ganglia contained within the bodies of Vertebrated 

 animals. In front of the vertebral column there is a chain of 

 oblong ganglia, which communicate with two large ganglia 

 that lie among the intestines, and with several small ganglia 

 in the head and other parts. They communicate also with the 

 posterior roots of the spinal nerves, on which are another set 



