1194 THE DIGESTIVE SYSTEM. 



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 under- 

 lying 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 ; (ft) 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 corre- 

 sponding 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 (6) will indicate the right limit, while the inferior limit is 

 marked by a line, convex downwards, drawn from the subcostal point (6) 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 

 cupolae 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 sterno- 

 costal 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 mid- 

 lateral 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 

 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 condi- 

 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 



