3H 



OF THE GLSOPHAGUS. 



[sect. 144. 



loops. The nerves are very numerous, and form superficial and 

 deeper plexuses ; the former Avith fine fibres, o'ooi'" to 0*0015'" in 

 diameter, which here and there divide, but whose ultimate ter- 

 mination is lost to view. 



2.— (ESOPHAGUS. 

 § 144. The walls of the oesophagus, i-\" r to if" thick, consist 

 externally of a fibrous coat of connective tissue, with well-marked 

 elastic fibres. Then follows a muscular coat, J'" to 1'" thick, with 

 an outer longitudinal layer of fibres, 0-5'" thick, and an inner 

 circular one, o"i^" to o - 3'", which lie close to each other. The 

 longitudinal fibres arise by two bundles from the constrictor 

 infimus, and by a third from the cricoid cartilage ; and from this 

 point, both layers extend as far as the stomach, into the muscular 

 coat of which they are in part continued. In the upper third of 

 the oesophagus, as far as its entrance into the thorax, these muscles 

 are transversely striped, and occasionally form distinct anasto- 

 mosing bundles, 004'" to o - 24'" in diameter. Further downwards, 

 smooth muscular fibres of the same structure as in the intestine 

 make their appearance, first in the circular and then in the longi- 

 tudinal layer, and increase more and more in number, till at last, 

 in the lower fourth, the smooth fibres form by far the majority. 

 According to Ficinus, however, single transversely striped fibres 

 are met with as far as the cardia. Treitz describes the longitudinal 



fibres as commencing by elastic 

 fibres, which are interposed be- 

 tween the transversely striped 

 bundles. Numerous longitudinal 

 bundles also branch off from the 

 outer surface of the oesophagus, 

 and are lost, partly among the 

 elastic fibres of the outer coat, 

 partly on the neighbouring or- 

 gans, especially on the poste- 

 rior wall of the trachea, on . 

 the left mediastinum [musculus 

 pleuro-assophageus, Hyrtl.), or 

 the aorta and left bronchus 

 {musculus broncho -oesophageus, 

 Hyrtl.). Most internally fol- 

 lows the pale -reddish, inferi- 

 orly whitish mucous membrane, 

 which is separated from the 



Fig. 132. 



Muscular fibre-cells from the oesophageal 

 mucous membrane of the pig, after treat- 

 ment with nitric acid of 20 per cent. Mag- 

 nified 150 times. 



