902 



PAROTID REGION. 



6. The cardiac branches of the vagus have no 

 direct effect in maintaining the movements of the 

 heart. Though the movements of the heart 

 may be materially influenced by causes acting 

 through the vagus, yet mental emotions and 

 injuries of the central organs of the nervous 

 system affect the heart's action through the 

 sympathetic after the vagi and recurrents have 

 been divided in the neck. 



7. The pulmonary branches of the vagus con- 

 sist chiefly of incident filaments and convey 

 impressions, capable of producing respiratory 

 muscular movements, made on the inner sur- 

 face of the lungs to the medulla oblongata. 

 When the vagi are cut or tied in the neck the 

 respirations instantly fall in frequency, and are 

 reduced to about one half their former number. 

 The existence of motor filaments in these 

 branches has not yet been satisfactorily esta- 

 blished. 



8. Though excitation of the nervus vagus 

 in the neck causes muscular contractions of the 

 stomach, yet the muscular movements of the 

 stomach are not entirely dependent upon the 

 gastric branches of the vagus, and the stomach 

 may still propel the chyme into the duodenum 

 after the vagi and recurrents have been divided. 

 Lesion of the gastric branches of the vagus does 

 not necessarily arrest the secretion of the usual 

 fluids poured out into the interior of the sto- 

 mach, though these are generally changed to a 

 considerable extent both in quantity and quality 

 by causes acting through the nervous system. 

 The rapidity of the absorption of poisonous 

 substances from the inner surface of the sto- 

 mach is not perceptibly diminished by the 

 division of the vagi. 



9. Division or ligature of the vagi in the 

 neck is almost always fatal. The cause of 

 death, in by far the greater number of cases, is 

 congestion of the lungs with blood induced by 

 the diminished frequency of the respiratory 

 muscular movements. In a few cases the ani- 

 mal dies of inanition from derangement of the 

 functions of the stomach.* 



(John Reid.) 



PAROTID REGION. This region (in 

 surgical anatomy) is of a somewhat pyramidal 

 form, the base corresponding to the surface of 

 the skin, and the apex to the pharynx. The 



* The author embraces this opportunity of cor* 

 reeling some of the errors which have been over- 

 looked in printing this article. 



P. 882, col. 1, 1. 11, for " cross," read "crosses." 

 ,, 2, foot note marked J, 1. 1 , for " en- 



largement," read '' arrangement." 



P. 888, col. 2, foot note, 1. 17,/or " while the 

 other two vagi, or," &c. to the end of the 

 sentence, read " while the other two vagi 

 give off the left recurrent of the right larynx 

 and the right recurrent of the left, as they 

 pass the larynges." 



P. 890, col. 1, last line, for " that in the," read 

 " that while in the." 



P. 890, col. 2, 1. 5, for " while the recurrent one 

 of the motor branches is," read " while 

 the recurrent, one of the motor branches, 

 is." 



P. 893, col. 1, last line except one, far " motor 

 filaments," read " sensiferous filaments." 



superficial boundaries of the region are, supe- 

 riorly, the root of the zygoma and the articu- 

 lation of the jaw; inferior ly, a line drawn from 

 the angle of the jaw to the anterior borderof the 

 sterno-mastoid muscle ; anteriorly, the posterior 

 border of the masseter muscle; and posteriorly, 

 the meatus auditorius, the mastoid process 

 with the anterior border of the sterno-mastoid 

 muscle. 



In the present article it is intended to give 

 the relative anatomy of the parts contained in 

 this irregular and ill-defined region. 



Commencing the dissection by removing the 

 integument from the parotid region, we expose 

 some delicate muscular fibres which constitute 

 the upper part of the platysma or the risonus 

 Santorini ; these fibres, however, are not con- 

 stantly present. After removing a fine reti- 

 cular tissue, the superficial surface of the pa- 

 rotid fascia is seen. This is a strong fibrous 

 fascia which is continuous below with the cer- 

 vical fascia ; it passes over the superficial sur- 

 faces of the parotid, being attached above to 

 the zygoma, and behind to the cartilage of the 

 ear, while in front it is thinner and is prolonged 

 over the masseteric region. The fascia also 

 dips down into the substance of the gland and 

 divides it into lobes and lobules. 



The Parotid Gland, from which the name 

 of this region is derived, is the largest of the 

 three salivary glands. Its form is irregular, and 

 is determined by the surrounding parts into the 

 interstices of which it is packed and moulded. 



Relations of the parotid. A description of 

 the relations of the parotid gland will include 

 the greater part of the relative anatomy of the 

 parotid region. The external surface or base 

 of the gland corresponds to the skin; it is of a 

 somewhat irregular quadrilateral form, and its 

 boundaries are identical with those of the pa- 

 rotid region, except that a portion of the gland, 

 the soda parotidis, is prolonged forwards with 

 the duct over the masseter muscle. The anterior 

 surface of the parotid is grooved to receive the 

 posterior border of the ramus of the jaw ; it 

 also corresponds to the internal pterygoid 

 muscle, the stylo-maxillary ligament, and the 

 masseter muscle, upon the external surface of 

 which it is prolonged, but separated from it by 

 some loose cellular tissue, by branches of the 

 portio dura nerve, and by the transverse facial 

 artery. The posterior surface corresponds 

 to the cartilaginous portion of the external 

 meatus, upon the convexity of which it is 

 moulded, and to which it is connected by 

 dense cellular tissue; this surface is also related 

 to the mastoid process and to the sterno-mas- 

 toid and digastric muscles. It is related supe- 

 riorly to the zygoma and the tempero-maxillary 

 articulation ; inferiorly it fills up the space be- 

 tween the angle of the jaw and the anterior 

 border of the sterno-mastoid muscle. It here 

 comes into relation with the submaxillary gland, 

 but is separated from it by the stylo-maxillary 

 ligament. The internal or deep surface of the 

 parotid is very uneven; it fills up the posterior 

 part of the glenoid cavity and the space be- 

 tween the ear and ramus of the jaw; it sur- 

 rounds the styloid process and the muscles 



