106 



VETERINARY PHYSIOLOGY 



When the consciousness is affected, vahiable information 

 as to the conditions of the surroundings may be afforded by 

 this sense in conjunction with the sense of touch. In 

 estimating the weight of bodies, these sensations are much 

 used. The body to be weighed is taken in the hand, and by 

 determining the amount of muscular contraction required 

 to support or raise it, the weight is judged. The shape and 

 size of objects are also determined by this sense in con- 

 junction with the sense of touch. In the dark, the distance 

 of objects is also judged by estimating the extent of move- 

 ment of the limb necessary to touch them. 



The sensibility to deep pressure which exists after section 

 of the cutaneous nerves must be due to a stimulation of 

 these receptors. 



B. Connection of Body Receptors with the 

 Central Nervous System. 



1. Ingoing Nerves. 



The ingoing nerves from these various receptors pass 

 towards the spinal cord in regular segmental series (fig. 46), 



PR 



Fig. 46. — Structure of a Typical Spinal Nerve. P.R., posterior root with 

 ganglion; A.R., anterior root; S.I., ganglion of sympathetic chain; 

 W.R., its white ramus ; G.B., its gre}' ramus; 1^.^^., visceral nerve 

 with collateral ganglion ending in terminal plexus; S.N., somatic 



nerve. 



except where the symmetry is interrupted by the outgrowth 

 of a limb. There the segmental arrangement is disturbed 

 into a pre-axial and post-axial arrangement. 



