THE BILIARY APPARATUS. 



1723 



right, where, after death, it reaches to the level of the sternal end of the fifth costal 

 cartilage. It is doubtful whether in life the liver is ever quite so high. On the left 

 it is about i cm. lower, and in the middle it is not more than 2 cm. lower still. 

 The relation of the left lobe to the floor of the thorax varies considerably. If large, 

 the organ may extend to the left wall, but this is rather uncommon. The liver 

 may reach the front wall as far to the left as the mammary line, in which case it will 

 be below nearly the whole of the floor of the pericardium, although it may not lie 

 below the anterior part. It always passes just in front of the cesophageal opening. 

 The inferior border rests against the posterior wall on the right, the diaphragm of 

 course intervening, at the right border of the right kidney near the end of the last 

 rib, on about the level of the second lumbar spine, and descends to the right along 

 the line of the eleventh rib. At the mid-axillary line it begins to rise, following 

 pretty closely the border of the thorax, to the ninth and tenth costal cartilages, 



FIG. 1458. 



VII rib-cartilage Transverse fissure 



rib-cartilage \ Left lobe | Falciform ligament 



Quadrate lobe 



vii rio-c 

 VI rib-cartilage 



VI rib 



VII rib 



VIII rib 



IX rib, 



Left supra 

 renal body 



Xrib. 



.Spigelian lobe 



Right supra- 

 renal body 



XI 



rib Diaphragm XII rib, head Diaphragm 



XII thoracic vertebra 



Frozen section across body at level of twelfth thoracic vertebra. 



after which it crosses the epigastrium to strike the left costal arch at the eighth car- 

 tilage. The notch for the round ligament is a little to the right of the median line 

 and the fundus of the gall-bladder at or near the end of the ninth right cartilage. 

 It is usually crossed by a vertical line from the middle of the clavicle. 1 . In the re- 

 cumbent position the liver gravitates to the top of the abdomen, so that normally 

 in the male no portion is left below the costal arch except near the middle. The 

 inferior vena cava runs in a groove on the back of the organ, but the aorta, passing 

 the diaphragm at a lower point, has the latter muscle between them. The vena cava 

 pierces the diaphragm at the level of the body of the ninth thoracic vertebra. The 

 lungs, especially the right, overlap the liver very considerably. 



Development and Growth. Very early, in the human embryo of 3.5 mm. 

 in length, a groove-like evagination appears on the ventral wall of the gut-tube, 

 immediately above the widely open vitelline duct. This evagination, the first indi- 

 cation of the hepatic anlage, extends into the primitive ventral or anterior mesentery 

 1 Carmichael : Journal of Anatomy and Physiology, vol. xxxvii., 1902. 



