112 



ANATOMY AND PHYSIOLOGY OF 



the gland or lobes are three principal ones 

 — right, middle, and left — to which smaller 

 ones are appended. 



The right lobe is the largest of the three, 

 situated in the right hypochondrium, being 

 thickest posteriorly and sharp anteriorly. 

 The supero-posterior part of the right lobe 

 is marked by a depression, for the adapta- 

 tion of the anterior part of the right kidney. 

 At the superior part of the right lobe is an 

 excavation for the vena cava, which extends 

 from behind forward, and marks off" the 

 division bet\,veen the right and middle lobe. 

 The vena cava is here more or less imbed- 

 ded in the substance of the right lobe, but, 

 generally speaking, it is superficial in the 

 horse, and only an imperfect channel is 

 formed for it. 



Projecting from the inferior surface and 

 posterior part of the right lobe, is the lobulus 

 spigelii, which is of considerable size, being 

 broad posteriorly, and attached by its 

 superior and left border, so that it projects 

 anteriorly and narrows ; its apex gradually 

 tapers, and has been capriciously designated, 

 by the lovers of a quintuple hepatic arrange- 

 ment, lobulus caudatus. 



The middle lobe of the liver is the smal- 

 lest of the three; it is crossed on its inferior 

 surface by the transverse fissure or porta of 

 the fiver, at which the vessels and ducts 

 enter into and issue from the gland. The 

 middle lobe in the horse is divided at its 

 anterior part into five or six portions, and 

 Mr. Percivall, in his Anatomy of the Horse, 

 at page 259, has termed it the lobulus 

 scissatus. It is traversed antero-posteriorly 

 by a channel for the remnant of the um- 

 bilical vein,W'hich eventually joins the vena 

 porta. 



The left lobe is the thinnest of the three, 

 but occupies an intermediate position in 

 length and breadth. It is very thin at its 

 left margin, and gradually thickens pos- 

 teriorly. At its posterior and left side is 

 a depression, in which the oesophagus rests. 

 Sometimes the left lobe is divided into two 

 at its anterior part ; at others it is single. 



The superior surface of the liver is convex, 

 and in contact with the pillars and expanded 



portion of the diaphragm. The right as 

 well as the Spigelian lobes, are in relation 

 posteriorly with the right kidney and right 

 supra-renal capsule, infcriorly with the head 

 of the pancreas, duodenum, and transverse 

 colon. The middle lobe is related inferiorly 

 to the pancreas, but partially separated from 

 it by the vena portae. It also suspends the 

 duodenum, and its left edge is loose and in 

 close proximity to the flexures of the colon. 

 The left lobe is related posteriorly to the 

 CESophagus, and inferiorly to the left end of 

 the stomach. The pancreas also stretches 

 across its posterior part, partially separating 

 it from the transverse colon. 



The liver receives an incomplete covering 

 of peritoneum. The latter, reflected from 

 the diaphragm on to the concave surface of 

 the middle lobe of the liver, forms a double 

 membranous layer, known, in accordance 

 with its shape, as the falsiform ligament, 

 and holding in its free and concave margin 

 the round ligament, the representative of a 

 foetal structure, the umbilical vein. Fur- 

 thermore, the fiver is provided with a coro- 

 nary ligament, that surrounds the foramen 

 dextrum of the diaphragm, through which 

 the vena cava passes. The lateral ligaments 

 are distinguished as right and left ; they 

 connect each lateral lobe to the diaplu-agm. 



The only connections of the liver that 

 remain to be mentioned are the stomach, 

 duodenum, transverse colon, and pancreas 

 to its inferior surface, and the right kid- 

 ney to the posterior part of the right lobe. 



Dissecting off the serous tunic, it is found 

 connected with the biliary surface by cel- 

 lular tissue, continuous at the porta with the 

 so-called capsule of Glisson. The latter 

 extends into the liver as a common sheath 

 to blood vessels, nerves, lymphatics, and 

 biliary ducts. 



To proceed with further description of 

 the liver would be useless, unless first ex- 

 amining the blood vessels and ducts in that 

 part of their course which is external to the 

 organ. The hepatic artery is quite subor- 

 dinate in size, considering the magnitude 

 of the organ and amount of its secretion. 

 It is a branch of the ccefiac axis, at first in 



