548 



SEVENTH PAIR OF NERVES. 



features in the anatomy of the seventh nerve, 

 which require a more artificial dissection or 

 examination for their verification. 



The origin of the portio intermedia, rather 

 more externally than the facial, has been al- 

 ready spoken of, and the nerve was then 

 traced to an union, more or less complete, 

 with the neighbouring vestibular portion of 

 the auditory nerve. Beyond this point the 

 views adopted respecting it, from being some- 

 what conflicting, become absolutely discor- 

 dant. 



The very different nature of the numerous 

 opinions upheld by various anatomists pre- 

 cludes the possibility of enumerating them 

 here at full length. Some of these, however, 

 have been already very briefly noticed ; and 

 perhaps, on the whole, the most prevalent was 

 that which supposed the portio intermedia to 

 give a branch which united with the vestibular 

 nerve, while the remaining portion passed 

 itself into the facial. 



More recently, the anatomy of the distribu- 

 tion and connections of this nerve seems to 

 have been fully made out by Morganti in an 

 elaborate monograph on the Genitulate gang- 

 lion * ; which is, I believe, chiefly known in 

 this country through the medium of an ex- 

 cellent analysis contained in one of Mr. Paget's 



men. Reports.f By careful dissection of the nerves, 



The infra-maxillary, or cervical portion of which he had previously hardened in nitric 



Liourhood of the transversalis faciei artery. 

 They mostly terminate in the upper half of 

 the orbicularis oris, and in the buccinator, on 

 -which muscle they join with the buccal branch 

 of the inferior maxillary division of the fifth. 

 This latter nerve is distributed to the mucous 

 membrane and integuments, and probably has 

 no share in the supply of the muscle. The 

 lower of these buccal branches join another 

 portion of the network, which results from 

 the ramification and union of the next division 

 of the facial. 



The cervico-facial division, of smaller size 

 than the temporo-facial, passes downwards 

 and forwards from the seat of bifurcation of 

 the portio dura, and emerges from the parotid 

 gland near the angle of the lower jaw. Here 

 it divides and subdivides in the same manner 

 as the preceding portion. It is divided into 

 a facial and cervical, or a supra and infra- 

 maxillary part. 



Its supra-maxillary part is constituted by 

 one or two large branches, which, breaking 

 up as they pass forwards to the interval be- 

 tween the jaw and mouth, enter beneath the 

 platysma and triangularis menti ; and besides 

 supplying these and the other muscles of this 

 region, they join with a branch of the inferior 

 dental which comes through the mental fora- 



the facial nerve, consists of two or three 

 branches, which, directed still more obliquely 

 downwards, soon divide into very numerous 

 filaments. These pass beneath the platysma 

 to gain the upper and anterior part of the 

 neck, where they form looped ramifications, 

 the most inferior of which are traceable in a 

 vertical direction to a short distance below 

 the hyoid bone. They are chiefly distributed 

 to the platysma, and above they join with the 

 neighbouring supra-maxillary branches just 

 mentioned. They unite beneath the platysma 

 with one, or more usually with two, branches 

 from the superficial cervical nerve of the cer- 

 vical plexus, which turns round the posterior 

 border of the sterno-mastoid muscle to supply 

 the integuments of the same part of the neck. 

 Little can be said with respect to the exact 

 nature of these very numerous junctions of 

 the facial nerve, either with the terminal 

 branches of the various divisions of the fifth, 

 or with the cutaneous nerves of the cervical 

 plexus. They offer a very obvious anatomical 

 resemblance to that intermingling of different 

 nerves which constitutes a plexus; but with- 

 out here specifying other distinctions, it may 

 suffice to point out that, in many instances, 

 the branches of the facial seem visibly con- 

 tinued in their previous direction beyond their 

 connections with the fifth. In the absence of 

 more minute investigations, this apparent in- 

 dependence can only be received as indicating 

 a partial involvement of the two nerves, or an 

 incomplete mixture of their fibres, in which 

 one gives to the other, or each gives to each, 

 a small number of its filaments, but retains the 

 large majority. 



We next proceed to consider those minuter 



i' succeeded in unravelling their 



aciu, Mor^ 



filaments ," and thus in separating the portio 

 intermedia from the facial and vestibular nerves 

 to a much greater extent than had hitherto 

 been accomplished. The general result of 

 this process was, that many of the so-called 

 anastomoses were shown to be mere relations 

 of propinquity, due to an intricate entangle- 

 ment, but not implying any real junction or 

 interchange of fibres. 



In the human subject. The portio inter- 

 media (fig. 405, 6), shortly after its origin, and 



Fig. 405. 



Diagram of the Portio intermedia and its branches. 

 (After Moryanti.) 



* Op. cit. 



f Ivoport on the Progress of Human Anatomy 

 and Physiology in the year 1841-5. British aiid 

 Foreign Medical Review. 



