Chap. XXIII.] 



OF THE HUMAN BRAIN. 



475 



proceed from or to the Viscera are mostly distributed along 

 the course of the Blood-vessels. Some of the fibres 

 of this system are specially distributed to the coats 

 of the Vessels, and are, from the nature of their 

 functions, known as 'vaso- 

 motor nerves.' A portion of . 

 these must have ' afferent ' func- 

 tions whilst others transmit 

 ' efferent ' impulses, causing the 

 vessels to contract, so that by 

 means of such nerves, the 

 amount of blood flowing through 

 particular vascular territories 

 may be easily regulated. The 

 ' vaso-motor ' nerves are con- 

 nected with small ganglia dis- 

 tributed over the vessels. To 

 some extent motor stimuli 

 emanate from these, though the 

 whole ' Vaso-motor ' system of 

 the body seems to be amenable 

 to the influence of a 'regulative 

 centre ' situated in the Medulla, 

 together with other subordinate 



Fig. 170.— One of the Sympathetic 

 Ganglia from the right Lateral Cord 

 of the Rabbit. (Owen, after Kol- 

 liker.) Tr, Literal cord of Sympa- 

 tem probably contains its own thetlc ; Rc, Rc, two communicating 



centres in the Spinal Cord. 

 Whilst the Sympathetic Sys- 



intrinsic afferent and efferent 



branches ; Spl, Splanchnic or Vis- 



ceral nerve ; s, small nerve ; g, gan- 



nerves, it also seems to send ^'^^^^ ^®"^ ^"^ ^^^^^- (^ about 40 



diameters.) 



(through the before -mentioned 



communicating filaments) afferent nerves to the grey 

 matter of the Spinal Cord, and to receive therefrom certain 

 efferent motor and other fibres. This great Sympathetic 

 System of nerves is to a certain extent an independently 



