28 PHYSIOLOGY AT THE FAKM. 



absolutely no state of consciousness interposed between an im- 

 pression on afferent nerves and the motion produced through 

 efferent nerves. For example, in a man apparently com- 

 pletely insensible from apoplectic seizure, a teaspoonful of 

 some drug being carried towards the back part of the tongue 

 makes an impression, succeeded, without any intervening 

 consciousness, by the contraction of the numerous muscles 

 concerned in deglutition. This is the most striking kind of 

 reflex action. 



Of the nerves supplied to the parts about the mouth and to 

 the pharynx and gullet, some are nerves of sense, some nerves 

 of motion ; or, according to the other mode of nomenclature, 

 some are afferent nerves, some are efferent nerves. All of 

 them are cranial nerves that is, are nerves derived from the 

 nervous parts within the head, commonly, yet not accurately, 

 included under the name brain. It is usual to reckon nine 

 pairs of cranial nerves. The second, third, fourth, and sixth 

 pairs belong exclusively to the eye. The fifth pair has an 

 extensive distribution : part of it is spent on the eye and 

 nose, while other parts of it are spread to the jaws, teeth, 

 lips, tongue, and palate. The fifth pair of nerves is the largest 

 of the cranial nerves : its filaments are chiefly nerves of sense, 

 and a portion of it is a nerve of special sense namely, the 

 gustatory nerve, or nerve of taste in the tongue while a por- 

 tion of it includes motor filaments, and these motor filaments 

 are spread upon the muscles of mastication. A portion of the 

 seventh pair belongs to the sense of hearing ; while the chief 

 remaining portion comes out upon the face, to become the 

 motor nerve of the face, and therefore is concerned in some of 

 the actions of the mouth. The eighth pair is a widespread 

 nerve : its chief destination is the stomach, but in its progress 

 it supplies the pharynx and gullet ; and a special division of it, 

 named the glosso-pharyngeal, is distributed to the tongue and 



