158 THE NERVES. 



three branches of the fifth nerve the ophthalmic is the most 

 motor ; and the superior maxillary the most sentient. The 

 inferior maxillary is of a mixed character ; presiding over a 

 particular function (mastication) ; and giving off a nerve of 

 special sense (the gustatory for taste) . 



The sixth, or abducent pair {Plate V. Fig 1 .6,6), arise 

 filamentary, to be chiefly given to the abductor muscle of 

 the eye, being purely motor. 



The seventh pair, or auditory {Plate V. Fig 1 .7, 7), 

 nerves, consist of two portions : that called the portio 

 mollis, enters the auditory foramen in a soft pulpy form, and 

 is distributed to the internal ear. The portio dura, which 

 composes the other branch, detaches a considerable twig 

 to the corda tympani : leaving the internal ear by the spiral 

 canal in a firm cord, it parts with branches to the inner 

 and outer parts of the ear : the main trunk then having 

 first furnished the parotid gland, and, being enlarged by 

 uniting with a branch from the maxillary of the fifth, next 

 passes over the hindermost part of the posterior jaw, con- 

 tiguous to the temporal artery ; and divides, its branches 

 diverging into the pes anserinus ; distributing muscular tw^igs 

 for motion about the face ; and joining the superior maxil- 

 lary upon the upper lip. 



The nervus vagus, or pneumogastric or eighth pair {Plate V. 

 Fig 1 . 8, 8), arise from the edge of the medulla oblon- 

 gata, in disgregated fibres ; and speedily divides into three 

 nerves. The first of these is the glosso pharyngeus ; which 

 is principally distributed to the tongue and pharynx. The 

 nervus vagus then proceeds down the neck in the sheath of 

 the carotid artery. Having reached the anterior aorta it 

 gives off the two recurrent nerves. The left recurrent 

 winds round the posterior aorta; and then changes its course, 

 going back again to become the inferior laryngeal nerve. 

 The right recurrent leaves the nervus vagus as it passes the 

 first ribs ; and without encircling any vessel, proceeds at 

 once to the larynx. The nervus vagus, now left alone, pro- 

 ceeds to supply the viscera of the chest and abdomen wdth 

 sensation ; blending with the various ganglia of the sym- 

 pathetic system. The nervus vagus is a mixed nerve ; but its 

 sentient branches predominate. It supplies the larynx with 

 motion- and it also gives it its exquisite sensation. It is 



