358 



NATURE 



[August 9, i 



entirely hypothetical, as might have been shown at any time by 

 stimulating the facial nerve in the skull, and observing the soft 

 palate. 



We have found that stimulation of the peripheral end of the 

 ■divided facial nerve in the internal auditory meatus failed to 

 •cause even with most powerful currents the slightest movement 

 of the soft palate, although the face was thrown into violent 

 spasm. The true motor nerve supply of the levator palati is, 

 according to our observations, the Xlth nerve {vide infra). 



IXth Ne7~ve. Glossopharyngeal.— After exciting this nerve, in 

 addition to the movements of the pharynx, which we attribute to 

 the contraction of the stylopharyngeus, and possibly to the 

 middle constrictor of the pharynx, we have observed certain 

 movements of the palate, as follows :— (i) Stimulation of the 

 nerve while beneath the stylo-hyoid ligament and uncut, gave in 

 two instances elevation of the palate on the same side, and in 

 one instance on both sides. We suppose that everyone will 

 consider with us this movement to be reflex in origin, but we 

 must add (2) that in one case we saw elevation of the palate to 

 the same side when exciting the peripheral end of the cut 

 nerve. In this latter case, perhaps, the result may be explained 

 by the close neighbourhood of the pharyngeal plexus and the 

 possible e cape of current thereto, and under any circumstances 

 this is but a single exceptional observation, so that we lay no 

 stress upon it. Finally we never saw movement of the soft 

 palate when the glossopharyngeal nerve was stimulated wiihin 

 the cranial cavity. 



Xth Nerve. Vagus. — In stimulating the uncut nerve outside 

 the skull, below the level of its junction with the hypoglossal, 

 rhythmical movements of swallowing were produced, which 

 •occurred at the rate of twenty-five times in thirty-five seconds. 



In one observation all the constrictors of the pharynx were 

 thiown into action, when the peripheral end of the cut nerve 

 was stimulated outside the skull. 



The rhythmical movements of swallowing obtained by stimu- 

 lating this nerve must be due to, of course, the simple reflex, the 

 stimulus acting on the nerve in the centripatal direction, and 

 that this was the case is proved by the fact that no movement was 

 obtained when the peripheral end of the cut nerve was stimulated 

 inside the skull. 



The superior laryngeal branch on being stimulated gave 

 rhythmical movements of swallowing at the rate of seventeen 

 times in fifteen seconds, but when the nerve was cut and its 

 peripheral end stimulated, only very slight movement was pro- 

 duced in the larynx, evidently by contraction of the crico-thyroid 

 muscle. 



Xlth Nerve. Accessory to Vagus.— In discussing the motor 

 functions of the Vllth nerve, we stated that the hitherto received 

 idea of the soft palate being supplied by the facial nerve was, 

 according to our observations, entirely erroneous. We find that 

 the levator palati is supplied entirely by the Xlth nerve. 1 

 When the peripheral end of the cut nerve was stimulated inside 

 the skull, elevation of the soft palate on the same side was 

 invariably seen. The path by which the fibres from this nerve 

 reach the palate is probably through the upper branch of the 

 pharyngeal plexus. 



Xllth Nerve. Hypoglossal— When the entire nerve was 

 excited outside the skull, just below the point where it is joined 

 by the first cervical nerve, the tongue was flattened posteriorly 

 on the same side, and the tip protruded also on the same side, 

 while in no case was there any heaping up of the tongue. 



At the same time the depressors of the hyoid bone were 

 thrown into action, and in some cases this dragging downwards 

 of the hyoid completely prevented the tongue from being 

 protruded. 



The movements described above were repeated without alter- 

 ation when the peripheral end of the cut nerve was excited at 

 the same place. 



It must be particularly noted that the movements of the tongue 

 were purely uni-lateral, and this was proved to be the case 

 beyond doubt by two experiments, in which the tongue was 

 divided longitudinally in the middle line to the hyoid bone, when 

 the movements were seen to be entirely confined to the side 

 stimulated. 



When the cut nerve was excited within the skull a different 

 result was obtained, the tongue was flattened behind, and pro- 

 truded towards the same side, but there was no action in the 

 depressors of the hyoid. 



1 I desire to add here that Dr. Felix Semon, in the course of some experi- 

 ments (unpublished), performed in conjunction with myself, found that in the 

 dog the levator palati was innervated by the Xlth nerve.— V. H. 



It has always been held that the depressors of the hyoid bone 

 receive their motor nerve supply from the hypoglossal through 

 the descendens noni, but, as will be shown further on, according 

 to our observation, these muscles are supplied by the first and 

 second cervical nerves, and it is only when the hypoglossal is 

 stimulated below the point where it is joined by the branch from 

 the first cervical nerve, that any movement is produced in the 

 depressors of the hyoid. 



B. Spinal Division. 

 Our observations of the motor functions of the first three 

 cervical nerves as regards their influence on the hyoidean muscles 

 have been made when the nerves have been excited — 

 (a) In the spinal canal. 



{b) In the neck immediately upon their exit from between the 

 vertebral transverse processes. 



The nerves in the spinal canal were separated from the spinal 

 cord and thoroughly dried, the efficacy of the precautions taken 

 against spread being evidenced by the difference in result 

 obtained by exciting each root. 



The effects obtained by the methods a and b were identical. 

 1st Cervical Nerve. Branch of Union with the Hypoglossal.— 

 In the description of the Xllth cranial nerve, we have stated as 

 the result of our experiments that the depressors of the hyoid bone 

 are not thrown into action when this nerve is stimulated within 

 the skull. On carefully dissecting out the branch from the 1st 

 cervical nerve to the hypoglossal we find on excitation of it that 

 there is no movement in the tongue, but the depressors of the 

 hyoid bone are strongly contracted. Of these muscles the 

 sterno-hyoid and sterno-thyroid were always especially affected, 

 while the omo-hyoid was less frequently seen to contract and in 

 some cases not at all. In the cases where this muscle contracted, 

 in one experiment the anterior belly alone acted, and when both 

 bellies contracted the movement in the anterior was in excess of 

 the posterior. 



J 2nd Cervical. Branch to the Descendens Noni. — On stimu- 

 lating this nerve the depressors of the hyoid were thrown into 

 action, but the muscles involved were not affected in the same 

 way as was the case with the 1st cervical nerve. The muscle 

 which was most constantly set in action by excitation of the Ilnd 

 cervical nerve was the omo-hyoid and especially its posterior 

 belly. The sterno-hyoid and sterno-thyroid also took part in de- 

 pressing the hyoid bone, but it was especially remarked in half 

 the cases, that their action was notably less powerful than that of 

 the omo-hyoid. In one experiment in which a very weak 

 current was employed, the omo-hyoid was alone seen to contract. 

 We are consequently led to conclude that while the sterno-hyoid, 

 sterno-thyroid, and omo-hyoid muscles are all set in action by 

 excitation of the 1st and Ilnd cervical nerves, the first two 

 muscles are relatively supplied by the former nerve, while the 

 Ilnd nerve is especially connected with the omo-hyoid muscle. 



Descendens Noni. — We prefer to mention here the results of 

 exciting this nerve, inasmuch as we regard its motor fibres to be 

 derived entirely from the 1st and Ilnd cervical nerves. This 

 nerve (ordinarily regarded as a branch of the Xllth cranial), 

 when stirhulated above its junction with the branch from the Ilnd 

 cervical nerve, produced contraction of the sterno-hyoid and 

 sterno-thyroid muscles, and where the current employed was 

 weak there was no contraction of the omo-hyoid, but this 

 movement was superadded on increasing the strength of the 

 current. 



We ought here to mention the opinion held by Volkmann (loc. 

 cit.) that fibres ascend to the hypoglossal from the spinal rami 

 communicantes by the descendens noni. 



Illrd Cervical Nerve. — On stimulating the branch from this 

 nerve, which forms the Ilnd cervical nerve just before the ansa 

 thus formed is connected to the descendens noni, there was no 

 action seen in the depressor of the hyoid bone ; it therefore seems 

 certain that these muscles are supplied with motor fibres solely by 

 the branches from the 1st and Ilnd cervical nerves. 



June 14. — " On Meldrum's Rules for Handling Ships in the 

 Southern Indian Ocean." By Hon. Ralph Abercromby, 

 F.R.Met.Soc. Communicated by R. H. Scott, F.R.S. 

 The results of this paper may be summarized as follows : — 

 The author examines critically certain rules given by Mr. C. 

 Meldrum for handling ships during hurricanes in the South 

 Indian Ocean, by means both of published observations and 

 from personal inspection of many unpublished records in the 

 Observatory at Mauritius. The result confirms the value of 



