STOMACH AND INTESTINE. 



325 



network ormatrlv; their blind extremities 

 being also imbedded in a considerable stratum 

 of this texture, which is continuous with that 

 surrounding their sides. The arrangement of 

 the latter part of it is best seen by making hori- 

 zontal sections of the mucous membrane, so 

 as to cut transversely across the gastric tubes 

 at different heights. Its quantity is small in 

 proportion to the diameter of the tubes. And 

 in it we may recognize, besides cut extremities 

 of vessels, indistinct concentric fibres, which 

 appear to surround the tubes, and decussate 

 with each other. In the ramified tubes of 

 many animals, each original tube, and its set 

 of secondary branches, is enclosed in a tole- 

 rably thick sheath of this kind, which gives 

 off slenderer partitions of the same nature 

 between the smallest individual tubes. On 

 the surface of the stomach, this matrix is 

 nearly homogeneous ; but its fibrous cha- 

 racter is more distinct at the deeper parts of 

 the membrane, and in those tubes which 

 occupy the neighbourhood of the pylorus. 

 Here its quantity is also increased. Many 

 years ago, the author was struck with the re- 

 markable difference between that layer of this 

 fibrous tissue which lies beneath the tubes, and 

 the submucous areolar tissue upon which it is 

 placed ; the former being characterized, 

 not only by its darker colour, and its dense 

 and closely interwoven texture, but also by 

 its being much less acted on by acetic acid. 

 But Middeldorpf * has since made the im- 

 portant discovery, that this peculiar layer, 

 which extends from the cardia to the anus, 

 is in reality composed of a mixture of 

 areolar tissue, and organic or unstriped 

 muscle: the fibres of the latter structure 

 being arranged in two series of bundles that 

 decussate with each other at an acute angle. 

 Externally, these fibres are conjectured by 

 Koelliker to be more or less continuous 

 with the ends of the oblique fibres of the 

 muscular coat. Internally, Bruecke states 

 them to pass upwards, in small bundles, 

 between the several tubes. This statement 

 is to some extent confirmed by Koelliker, 

 who has seen numerous cells very like 

 the fibre-cells of organic muscle occupying 

 this situation in Man, some Ruminants, and 

 the Pig. In the latter animal, bundles of these 

 fibres penetrate the rudimentary villi of the 

 pylorus, and occupy their axes. Of the 

 function of these muscular-fibre cells we 

 know nothing. But, from their arrangement, 

 it would seem not impossible that they are 

 destined to maintain the tubes in their normal 

 situation, against the disturbances which the 

 contractions of the proper muscular coat might 

 otherwise produce. 



Areolar tissue. A layer of loose submucous 

 areolar tissue (the tunica nervea of some 

 authors) connects the mucous membrane of the 

 stomach with the proper muscular coat pre- 

 viously described. Seen in vertical section, its 

 thickness is a little greater than that of the 

 denser muscular stratum which receives the ex- 



* De glandulis Brunnianis. Vratial : 1846. 



tremities of the tubes. Its constituents are 

 the ordinary white and yellow fibrous ele- 

 ments ; the elastic filaments of the latter 

 being chiefly of small size. Externally, it 

 is pretty firmly connected with the muscular 

 coat, and appears to receive many of its 

 fibres. But internally, where it approaches 

 the fibrous matrix, its meshes are very 

 large and loose, so as to allow of the 

 mucous membrane being thrown into folds by 

 the contraction of the muscular tunic, ft 

 contains the vessels, nerves, and lymphatics 

 destined for the supply of the mucous mem- 

 brane. 



The vessels of the stomach are very large 

 and numerous. The arteries are derived from 

 the abdominal aorta. The veins empty 

 themselves into the vena portcE, which rami- 

 fies in the liver. 



The arteries of the stomach all come off 

 from the cceliac axis. This vessel, which 

 leaves the aorta opposite the first lumbar 

 vertebra, continues obliquely forwards as a 

 short thick trunk for a distance of about half 

 an inch; when the "axis" ceases, by giving 

 off, at right angles to itself, three large 

 branches : namely, the gastric, hepatic, and 

 splenic. 



Fig. 250. 



Arteries of the stomach. The cceliac axis, as seen by 

 raising the liver, and depressing the stomach. 



a, arteria coronaria ventriculi ; b, gastric branches 

 of the same; c, arteria hepatica; d, arteria gastro- 

 duodenalis; e, arteria gastro-epiploica dextra; g, 

 arteria pylorica ; h, arteria splenica ; ?', arteria gastro- 

 epiploica siuistra. 



The arteria coronaria ventriculi (a, figs. 250, 

 25 1 .), or proper gastric artery, is the smallest of 

 these three. It passes upwards and towards the 

 left side, beneath the peritoneum which forms 

 the dorsal and outer surface of the sac of the 



Y 3 



