FUNCTIONS OF NERVES. 



portion of the spinal chord is nearly insensible, while its posterior 

 portion, and all the ganglionic branches of the trigeminum, are 



Nerv. Syst. of the Hum. Body, 1 830, p. viii. In this work are various papers 

 presented by him to the Royal Society during the preceding nine years. ) Sir C. 

 Bell also discovered the facial to be a nerve of motion only, though, besides 

 speaking of it as a nerve of voluntary motion, he gave it some properties of ex- 

 pression which are common to all nerves of voluntary motion, and strangely called 

 it a respiratory nerve. Our knowledge of the functions of the anterior and the 

 posterior or ganglionic portion of the spinal nerves, we owe first to Sir C. Bell, 

 and next to Dr. Magendie. In a tract privately circulated by Sir C. Bell in 

 1811, he stated that, on dividing the posterior spinal nerves, no motion ensued ; 

 but that, on touching the anterior, the muscles of the back were instantly con- 

 vulsed, (p. xvii. sq. ) He concluded that the anterior and posterior portions 

 had different functions, and that the anterior gave motion ; but he went no far- 

 ther : and even fancied that the anterior gave sensibility also, and that the pos- 

 terior might have other functions altogether. Dr. Magendie, many years later, 

 proved that the anterior nerves gave motion only, and the posterior sensation. 

 (Journal de Physiologic, t. ii. ) Had Sir C. Bell been aware of these, the true 

 functions, he would not have neglected to set forth a discovery which he views 

 in his later writings as so great. 



While a branch of the trigeminum was supposed to be a nerve of taste a 

 special sense, there was a great want of uniformity in our views of its offices. 

 It resembled the spinal nerves, in having a ganglionic and an aganglionic root. 

 The aganglionic had been shown by Paletta to be for motion only. Every 

 body knew that the ganglionic portion was for sensation. For example, Blu- 

 menbach said, when treating of smell, that the first pair was for this sense, but the 

 trigeminum for the common sensibility of the nostrils. Still the ganglionic 

 portion was thought to be a nerve of motion also, and this was Sir C. Bell's 

 opinion ; for his first experiment seemed merely to corroborate the common belief, 

 that the ganglionic portion was for sensation and motion. After he had made 

 many experiments he concluded it was for sensation only, and, although he is right 

 in regarding it as a nerve of sensation only, he and others appear incorrectly to 

 ascribe a number of facts regarding paralysis of motion in the face to the seventh, 

 that really depend upon the trigeminum, though not upon the ganglionic portion 

 but upon the aganglionic portion, as Dr. O'Beirne has so well shown. In fact, the 

 truth of the ganglionic portion of the trigeminum being for sensation only was in 

 some measure incorrectly inferred by Sir C. Bell from his experiments and cases, 

 exceptions being passed over or unsatisfactorily explained. They all admit, 

 however, of easy explanation, by referring impairments of motion on dividing 

 the ganglionic branches to the extensive ramifications of the aganglionic por- 

 tion in conjunction with those of the inferior maxillary branch ; and, where any 

 paralysis of motion appeared on dividing the superior maxillary branch, to the 

 necessary injury of one head of the levator labii superioris alseque nasi. From 

 reviewing every circumstance, there can be no question that Sir C. Bell's 

 view, of the ganglionic portion being for sensation only, is true. Still he has left 



