a 
1068 THE DIGESTIVE SYSTEM. 
conunonly present in the foetus (Thomson). Or the liver may be divided up into a large number 
of distinct lobes, as in most other animals. 
Changes in position have been already referred to in connexion with variations in form ; 
there need only be added here that the liver ascends and descends at every expiration and i inspira 
tion respectively, and that it also descends, but very shghtly, in changing from the rechning to 
the erect posture. Occasionally, without any evident cause, the liver “and diaphragm are found 
to occupy a higher or lower position than usual. 
Fixation of the Liver.—At first sight it is not easy to understand the means by which 
the liver maintains its position in the abdomen (and the same remark applies, perhaps, to other 
solid abdominal organs). The falciform ligament probably gives it no support, as it is quite lax 
when in the body. Nor can it be said that its vessels, except perhaps the hepatie veins, assist. 
However, on considering the conditions under which the viscera are placed in the abdominal 
cavity the problem becomes less difficult. 
The abdomen is a closed cavity, with a firm framework to its up per part, a tightly stretched 
diaphragm for its roof, and muscular walls all round. Into the cone: wity of this roof the parietal 
surtace of the liver is fitted with perfect accuracy, so that the two are in absolute contact, and 
cannot be separate -d without producing a vacuum, unless some other structure is in a position to 
fill the space. But there is hardly any other viscus movable enough to pass up over the front 
of the liver into the vault of the di: aphragin, so that atmospheric pressure alone is probably 
sufficient to retain the organ 7 situ, as in the case of the hip Joint. In addition, the abdominal 
muscles are always in a condition of tonic contraction or “ tone,” which gives rise to an intra- 
abdominal pressure. This is effective in all direc ‘tions, and consequently there is a considerable 
pressure on ay the abdominal walls. The liver, being in absolute contact with the roof, m: iy be 
considered a part of this wall, and it is consequently affected by this pressure which helps to 
sustain it. Add to this, the support which the organ receives from the intestines, the stomach, 
and the pancreas ; from the coronary and lateral ligaments; from the connexion of the back of 
the right lobe by areolar tissue to the diaphragm ; and, finally, from the vena cava embedded in 
the ieee and se nding its hepatic veins forwards to all parts of the organ, just before the cava 
itself is firmly attached to the margins of the caval orifice in the central tendon of the 
diaphragm, and we will probably find sufficient cause for the maintenance of the organ in its 
position in the abdominal cavity. 
THE GALL-BLADDER AND BILE-PASSAGES. 
Under this heading we have to consider the hepatic ducts, the gall-bladder, 
the cystic duct, and the common bile-duct. 
The excretory ducts of the liver (Fig. 718) begin within the hepatic lobules as minute 
channels, running between the hepatic cells (Fig. 721), and known as the bile canaliculi 
(ductus biliferi). 
Outside the lobules these join (Fig. 721) the interlobular ducts (ductus interlobu- 
lares), which latter by uniting form ae and larger ducts, and finally end in two, or 
more, chief hepatic les a larger from the right, and a smaller from the left lobe, w iflet 
unite immediately after leaving the liver to form the hepatic duct. 
As a rule, five or six ducts leave the liver at the bottom of the portal fissure ; these generally 
unite into right and left main ducts ; sometimes they all converge towards, and unite at the 
begining of ‘the hepatic duct. It is interesting to note that the finer from the Spigehan and 
caudate lobes j join the left main duct. 
The hepatic duct (ductus hepaticus), formed at the bottom of the portal fissure 
by the union of right and left chief ducts (Fig. 718), passes downwards, with an 
irregular course, and, just outside the mouth of the portal fissure, is joined by 
the cystic duct (Fig. 718) to form the common bile-duct. In length it usually 
measures about 1 to 14 inches (25 to 31 mm.), and in breadth, when flattened 
out, nearly + inch (6 mi.), or about as much as a goose quill, It lies, practically 
altogether, within the portal fissure. 
The gall-bladder (vesica fellea), with its cystic duct, may be looked upon as a 
diverticulum of the bile-duct, enlarged at its extremity to form a reservoir for the 
bile. It is pear-shaped, and lies obliquely on the under surface of the liver (Fig. 
718). The wide end, or fundus, usually reaches the inferior border of the iver—where 
there 1s ee a notch to receive it—and comes in contact with the anterior 
abdominal wall (Fig. 714). The body (corpus) runs backwards, upwards, and to the 
left, lying in the fossa of the gall-bladder, and near the portal fissure passes rather 
abruptly into the narrow neck. The neck (collum) is curved inwards towards the 
portal fissure, in the form of the italic letter s, and when distended it presents the 
appearance of a spiral constriction which is continued into the beginning of the 
