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is separated from it by the fossa for the ductus venosus. The groove leads down. into the gastric impression on the inferior surface of the left lobe (Fig. 938), and, when in the body, lies in contact with the prominent right or anterior margin of the oesophageal orifice of the diaphragm (see p. 1152 and Fig. 912), sometimes also with the oesophagus itself.
Facies Inferior.-The inferior or visceral is an irregular, obliquely sloping surface (Fig. 938), which looks downwards, posteriorly, and to the left, and rests upon the stomach, lesser omentum, intestines, and right kidney. The division into right and left lobes is indicated on this surface by the left sagittal fossa, which passes from the umbilical notch at the anterior border back to the porta hepatis, and thence backwards as the fossa for the ductus venosus.
The inferior surface of the left lobe is directed downwards and posteriorly, and
Inferior vena cava in its fossa
Right end of caudate process
FIG. 938.-INFERIOR OR VISCERAL SURFACE OF THE LIVER.
Attachment of right triangular ligament
rests on the superior surface of the stomach, in front of the cardia; also on the lesser curvature with its attached lesser omentum. The part which rests upon the anterior surface of the stomach is rendered concave by the pressure of that organ (Fig. 938), and is known as the impressio gastrica; whilst the portion to the right of this, being free from the pressure of the stomach, projects backwards over the lesser curvature against the lesser omentum in the form of a smooth rounded prominence, and is known as the tuber omentale.
The inferior surface of the right lobe may be divided into two portions by the line of the gall-bladder, which extends forwards in its fossa to the anterior sharp margin of the liver (Fig. 936).
(a) To the left of the line of the gall-bladder are found from before backwards :The lobus quadratus, porta hepatis, and processus caudatus.
The quadrate lobe is of an oblong shape, the antero-posterior diameter being the greatest. Its surface is generally concave, and is related to the pylorus and the adjacent parts of the stomach and duodenum, when the former is distended. When the stomach is empty, however, the
pylorus usually lies beneath the right portion of the left lobe, and the superior part of the duodenum lies beneath the quadrate lobe, the transverse colon also coming in contact with it anteriorly (Fig. 938).
(b) The surface to the right of the gall-bladder, which is more extensive than that on its left, is entirely occupied by three impressions, produced by the underlying viscera-namely: (1) The impressio colica lies in front and to the right of the gall-bladder. It is formed by the right flexure of the colon and the beginning of the transverse colon. (2) Behind this is the impressio renalis, larger than the preceding, which is produced by the superior half or two-thirds of the right kidney. It is placed behind the colic impression just as the kidney itself is placed behind the colon. The superior end of the renal impression is frequently devoid of peritoneum (Fig. 938), that is to say, the "uncovered area" of the right lobe extends down over the impression for a little way. This impression is very deep, and accommodates nearly the whole thickness of the kidney. In many hardened specimens it would appear to belong more to the posterior part of the parietal surface than to the inferior or visceral surface. (3) To the medial side of the renal impression, and near the neck of the gall-bladder, is placed the narrow impressio duodenalis, which lies in contact with the descending part of the duodenum down to the point at which it is crossed by the colon.
Surface Markings of the Liver.-The limits even of the normal liver are very variable, but, taking the average condition in the male, they may be marked out on the anterior surface of the body by the following method:-Three points are determined (a) half an inch (12.5 mm.) below the right nipple; (b) half an inch (12.5 mm.) below the right margin of the thorax (or below the tip of the tenth rib); and (c) one inch (25 mm.) below the left nipple. If these points are joined by three lines, slightly concave towards the liver, they will give the outline of the organ with sufficient accuracy for all ordinary purposes. (For variations in position see below.)
To state the matter somewhat more in detail:-If the two "nipple points" (a) and (c) be joined by a line, slightly convex upwards on each side, but a little depressed at the centre corresponding to the position of the heart, and crossing the inferior end of the sternum about the level of the seventh cartilage, it will mark the superior limit. A line, convex upwards, from the right nipple point (a) to the subcostal point (b) will indicate the right limit, while the inferior limit is marked by a line, convex downwards, drawn from the subcostal point (b) to the left nipple point (c), and passing through a point half-way between the umbilicus and the inferior end of the body of the sternum, in the median line.
The line indicating the superior limit of the liver is elevated on each side, corresponding to the cupola of the diaphragm, and depressed in the centre beneath the heart. On the right side where highest, namely, about one inch (25 mm.), medial to the mammary line, it reaches during expiration to the superior border of the fifth rib; on the left side it is one-half to three-quarters of an inch (12 to 18 mm.) lower; and it crosses behind the sternum at the level of the sixth sternocostal junction-or sometimes lower. It must be remembered, however, that, whilst the liver reaches up to the levels just given, it does so only at the highest part of its convex parietal surface, and is separated from the ribs all round by the thin lower margin of the lung (which extends down between the chest wall and diaphragm to the sixth rib in front, to the eighth in the midlateral line, and to the level of the tip of the spine of the tenth thoracic vertebra behind), so that, in percussing over the liver, its dulness is obscured by the resonance of the lungs above these points.
From the back, the superior margin of the liver rises as high as to the superior margin of the eighth rib or to the inferior margin of the scapula on the right side. On the left, it rises to the inferior margin of the eighth rib, and terminates about an inch medial to the inferior angle of the scapula.
The inferior margin slopes upwards along the eleventh rib of the right side, along a line leading to the superior part of the tenth thoracic vertebra. On the right side the liver extends vertically in the mid-axillary line from the sixth to the eleventh ribs.
Variations in Size, Form, and Position.-Few organs will be found to vary more in size in different bodies than the liver; these variations, however, are very frequently to be looked upon as pathological. But even the normal, healthy liver may vary in weight from 48 to 58 ounces I in the adult male, and from 40 to 50 ounces in the female.
Variations in form and position doubtlessly take place physiologically, as a result of the cond:tions of fulness or emptiness of the adjacent viscera; for, though the liver, like the other solid abdominal organs, has an intrinsic shape of its own, this is capable of modification within certain limits by the varying pressure of the surrounding parts. Thus, distension of the stomach, or of a portion of the transverse colon lying in the stomach chamber, may push the liver over to the right, so that it may hardly reach the median plane, and at the same time it increases its vertical
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depth. On the other hand, a distended state of the small intestines, with a contracted stomach and colon, may have the opposite effect, flattening it from below upwards and enlarging it in the transverse direction.
Variations in form and position due to malformations of the thoracic framework, either congenital or acquired, are very common, particularly in females as a result of tight-lacing, which presses the lower ribs inwards. Sometimes in these cases the constriction of the waist lies chiefly below the liver. The organ is then forced up against the diaphragm, filling its whole vault, and extending across to the left abdominal wall, where its left margin may lie in the interval between the diaphragm and the spleen. But more commonly it would seem that the liver is caught by the constriction: its upper part is then closely pressed into the vault of the diaphragm, which, owing to the narrowing of the thorax, is unable to accommodate the whole organ, so that its inferior part is crushed down for a considerable distance into the umbilical zone of the abdomen (Fig. 918, p. 1167), particularly on the right side. Often, too, a wide, tongue-like process (the so-called "Reidel's lobe") descends from the inferior margin, lateral to the gall, bladder. This process, which when very large may reach to the iliac crest, is sometimes found in men, although more common in women, and is liable to be mistaken for a tumour. A somewhat similar process occasionally descends from the left lobe.
Again, in apparently healthy bodies the liver may extend up on the right side almost to the fourth rib; whilst in other cases it may be as low as the sixth rib, or even lower. Nor is it rare-particularly in females-to find the anterior border projecting two or three inches (50 to 7:54 cm.) below the margin of the thorax on the right side (Fig. 918, p. 1167).
Reference should be made here to certain grooves often seen on the liver. Some of these are found running obliquely low down at the right side where the liver is in contact with the ribs; they are particularly common in females, and are due to the pressure of the ribs resulting from tight-lacing. Grooves of a different kind are found at the superior part of the parietal surface; where the liver is in contact with the diaphragm; these usually run radially, that is, in the direction of the muscular fibres of the diaphragm, and are apparently produced by a wrinkling, or irregular contraction, of the diaphragm. At least, ridges of the diaphragm are found lying in the grooves, and these ridges or wrinkles would seem to be responsible for the production of the grooves.
Finally, the liver may present certain congenital irregularities in the direction of additional fossæ and lobes, which reproduce the conditions found in the higher apes, and are very commonly 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 inspiration respectively, and that it also descends, but very slightly, in changing from the reclining 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 gives it no support, as it is quite lax when in the body. Nor can it be said that its vessels, except perhaps the hepatic 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 superior part, a tightly stretched diaphragm for its roof, and muscular walls all round. Into the concavity of this roof the parietal surface of the liver is fitted with perfect accuracy, so that the two are in absolute contact, and cannot be separated 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 diaphragm, so that atmospheric pressure alone is probably sufficient to retain the organ in situ, as in the case of the shoulder joint. In addition, the abdominal muscles are always in a condition of tonic contraction or "tone," which gives rise to an intraabdominal pressure. This is effective in all directions, and consequently there is a considerable pressure on all the abdominal walls. The liver, being in absolute contact with the roof, may 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 triangular ligaments; from the connexion of the back of the right lobe by areolar tissue to the diaphragm; and, finally, from the inferior vena cava embedded in the liver and sending its hepatic veins forwards to all parts of the organ, just before the vein 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.
Relation to Peritoneum.-The relation of the liver to the peritoneum is somewhat complex in its details. The greater part of the liver is covered with peritoneum, forming the tunica serosa, but there is an area of some size upon its superior and posterior aspects where it is directly in contact with the diaphragm, and round the margins of this area the peritoneum passes from liver to diaphragm. This is known as the bare area, and the peritoneum around this area is known as the ligamentum coronarium (coronary ligament). Further, the liver is attached to the
anterior portion of the diaphragm, and to the abdominal wall as low as to the umbilicus by a fold of peritoneum which is known as the ligamentum falciforme. This fold runs forwards from and is continuous with the folds of peritoneum which limit the bare area, and the whole forms a sort of mesentery or meso-hepaticum.
The peritoneum is also reflected off from the margins of the porta hepatis and from the fossa for the ductus venosus, and passes thence to the lesser curvature of the stomach and the first part of the duodenum, forming the omentum minus, The liver may, in fact, be regarded as lying inside a peritoneal fold which stretches from the lesser curvature of the stomach below to the diaphragm and anterior abdominal wall above. This fold is embryologically the ventral mesentery of the stomach, or ventral meso-gastrium, and its original simple character has become complicated by the growth of the liver within it and by the rotation which the stomach undergoes to the right side at its inferior part.
The various ligaments of the liver are as follows:
(1) Ligamentum Falciforme Hepatis. The falciform ligament of the liver is a crescentic fold of peritoneum, which is attached by its convex border to the inferior surface of the diaphragm, and to the anterior abdominal wall (an inch or more to the right of the median plane) to within a short distance (1 to 2 inches, 2·5 to 5 cm.) of the umbilicus. Its concave border is attached to the superior and anterior aspects of the liver; below this level it presents a free rounded edge, stretching from near the umbilicus to the umbilical notch of the liver, and it contains within its layers a stout fibrous cord called the round ligament.
Near the posterior part of the superior surface of the liver the two layers of which the falciform ligament is composed separate, and enclose a triangular area on the posterior surface, in front of the superior end of the vena cava, uncovered by peritoneum. Traced backwards, the right layer passes into the superior layer of the coronary ligament, the left into that of the left triangular ligament. It is the remains of a part of the ventral mesentery of the embryo, and has no supporting or suspensory action on the liver of the adult.
(2) Ligamentum Coronarium Hepatis.-The coronary ligament consists of the layers of peritoneum which are reflected from the liver to the diaphragm at the margins of the uncovered area of the right lobe. The name of right triangular ligament has been given to its pointed right extremity (Fig. 938).
The coronary ligament consists of a superior and an inferior layer. The superior is formed by the prolongation to the right of the right layer of the falciform ligament. inferior layer is formed by the continuation of the inferior layer of the right triangular ligament to the left side, and by the reflection from the margin of the caudate lobe by the side of the inferior vena cava (see Fig. 938).
(3) Ligamentum Triangulare Dextrum.-The right triangular ligament (O.T. right lateral ligament) is merely the pointed right extremity of the coronary ligament, wher the superior and inferior layers become continuous with one another.
(4) Ligamentum Triangulare Sinistrum. The left triangular ligament (O.T. left lateral ligament) is a considerable triangular fold, continuous with the left layer of the falciform ligament, which is attached by one border to the superior surface of the left lobe near its posterior border, and by the other to the diaphragm, for a distance of several inches as a rule.
Its attachment to the diaphragm lies nearly altogether to the left of the oesophageal orifi.r. and about 3 inch (18 mm.) anterior to the plane of this opening.
Two other structures, termed ligaments, are not peritoneal folds, but obliterated bloodvessels, namely the ligamentum teres hepatis or round ligament and the ligamentum venosum (Arantii).
(5) Ligamentum Teres Hepatis.-The round ligament of the liver is a stout firs band which passes from the umbilicus, backwards and upwards, within the free margin the falciform ligament, to the umbilical notch of the liver, and thence upwards y backwards in the umbilical fossa, to join the left branch of the portal vein. It is ta remains of the left umbilical vein, which, before birth, carries the arterial blood from the placenta to the body of the foetus (Fig. 88).
(6) Ligamentum Venosum Arantii.-The venous ligament of Arantius (O.T. obliter ated ductus venosus) is a slender fibrous cord, which passes from the left branch of the portal vein, nearly opposite the attachment of the round ligament, upwards in the foss
bearing its name, to be connected with the inferior vena cava as it leaves the liver. In the foetus this structure is a considerable vessel, which conveys some of the blood brought to the porta hepatis by the left umbilical vein directly backwards to the vena cava. At the time of birth the ductus venosus and umbilical vein cease to carry blood, their cavities become obliterated, and they are converted into fibrous cords.
(7) Omentum Minus. The lesser omentum is a fold of peritoneum which extends from the liver to the lesser curvature of the stomach and to the duodenum.
It is attached, above, to the margins of the porta hepatis, and also to the bottom of the fossa for the ductus venosus. Below, it is connected to the lesser curvature of the stomach, where its two layers separate to enclose that organ, and also to the upper border of the duodenum for an inch or more beyond the pylorus. Between its layers, close to its right or free border, are contained the bile duct, the hepatic artery, the portal vein, and the nerves and lymph vessels passing to and from the porta hepatis (Fig. 939). Its central part is wide, but it is narrow at each end. Of the two ends, the right is free, and
FIG. 939.-THE LESSER OMENTUM.
The left lobe of the liver has been removed, and also the anterior layer of the hepato-duodenal ligament. The view is taken looking upwards as well as backwards.
stretches from the liver to the duodenum, forming the anterior boundary of the foramen epiploicum. The left end is very narrow, and is attached to the diaphragm between the oesophageal and caval openings. The portion of the lesser omentum passing between the liver and the stomach is known as the ligamentum hepatogastricum; that between the liver and the duodenum is called the ligamentum hepatoduodenale.
The reflection from the liver to the superior part of the right kidney (a portion of the inferior layer of the coronary ligament) is termed the hepato-renal ligament.
The "bare area" of the liver is triangular in shape, and measures about 3 inches in its greatest vertical extent, and some 5 inches transversely. It is in contact with the diaphragm, a portion of the right suprarenal gland, and the inferior It is bounded above and below by the superior and inferior folds of the coronary ligament, and on the left by the attachment of peritoneum to the margin of the caudate lobe. It is prolonged upwards for a short distance on the superior surface of the liver, in front of the inferior vena cava, between the layers of the falciform ligament as they diverge from one another.