Anatomy of Liver

LIVER, ANATOMY OF. The liver is a large reddish brown gland situated in the upper and right part of the abdominal cavity. When hardened in situ its shape is that of a right-angled, triangular prism showing five surfaces—superior, anterior, in ferior, posterior and right lateral which represents the base of the prism. It weighs about three pounds or one-fortieth of the body weight. The liver is plastic, and moulds itself to neighbouring viscera. The superior surface is in contact with the diaphragm, but has peritoneum between (see COELOM AND SEROUS MEMBRANES ) . At its posterior margin the peritoneum of the great sac is reflected on to the diaphragm to form the anterior layer of the coronary ligament. Near the mid line of the body, and at right angles to the last, another reflection, the falciform ligament, runs forward, and the line of attachment of this indicates the junction of the right and left lobes of the liver. The anterior surface is in con tact with the diaphragm and the anterior abdominal wall. The attachment of the falciform ligament is continued down it. The posterior surface is more complicated (fig. I) ; starting from the right and working toward the left, a large triangular area, uncov ertd by peritoneum and in direct contact with the diaphragm, is seen. This is bounded on the left by the inferior vena cava, which is sunk into a deep groove in the liver, and into the upper part of this the hepatic veins open. Just to the right of this and at the lower part of the bare area is a triangular depression for the right suprarenal body. To the left of the vena cava is the Spigelian lobe, which lies in front of the bodies of the tenth and eleventh thoracic vertebrae, the lesser sac of peritoneum, dia phragm and thoracic aorta intervening. To the left of this is the fissure for the ductus venosus, and to the left of this again, the left lobe, in which a broad shallow groove for the oesophagus may usually be seen. Sometimes the left lobe stretches as far as the left abdominal wall, but more often it ends below the apex of the heart, which is 31in. to the left of the mid line of the body. The relations of the lower surface can only be understood if it is real ized that it looks backward and to the left as well as downward (fig. 1). Again starting from the right side, two impressions are seen the anterior one is for the hepatic flexure of the colon, and the posterior for the upper part of the right kidney. To the left

of the colic impression is a smaller one for the second part of the duodenum. Next comes the gall bladder, a pear-shaped bag, the fundus of which is in front and below, the neck behind and above. From the neck passes the cystic duct, which is often twisted into the form of an S. To the left of the gall bladder is the quadrate lobe, which is in contact with the pylorus of the stomach. To the left of this is the left lobe of the liver, separated from the quad rate lobe by the umbilical fissure in which lies the round ligament of the liver, the remains of the umbilical vein of the foetus. The under. surface of the left lobe is concave for the anterior surface of the stomach (see ALIMENTARY CANAL), while on the other hand a convexity (tuber omentale) fits into the lesser curvature of that organ. The posterior boundary of the quadrate lobe is the transverse fissure, which is little more than an inch long and more than half an inch wide. This fissure represents the hilum of the liver, and contains the right and left hepatic ducts and the right and left branches of the hepatic artery and portal vein, together with nerves and lymphatics, the whole being enclosed in con densed subperitoneal tissue known as Glisson's capsule. Behind the transverse fissure the lower end of the Spigelian lobe is seen as a knob, and from the right of this a narrow bridge runs forward and to the right to join the Spigelian lobe to the right lobe and to shut off the transverse fissure from that for the vena cava. This is the caudate lobe. The right surface of the liver is covered with peritoneum and is in contact with the diaphragm, outside which are the pleura and lower ribs. From its lower margin the right lateral ligament is reflected on to the diaphragm. A similar fold passes from the tip of the left lobe as the left lateral liga ment, and both these are the lateral margins of the coronary liga ment. Sometimes, especially in women, a tongue-shaped projection downward of the right lobe is found, known as Riedel's lobe; it is of clinical interest as it may be mistaken for a tumour or floating kidney. The right and left hepatic ducts, while still in the trans verse fissure, unite into a single duct which joins the cystic duct from the gall bladder at an acute angle. When these have united the duct is known as the common bile duct, and runs down to the second part of the duodenum (see ALIMENTARY CANAL).